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 1 EFFECTS & AVOIDANCE OF LIGHTNING STRIKES ON AICRAFT by BEATRIZ ESCARTIN CLAVERIA A project report submitted to the School of Science and Technology in partial fulfilment of the requirements for the Bachelor of Engineering In Aeronautical Electronics Engineering (Avionics) APRIL 2010 Supervised by: Cedric Belloc Senior Lecturer/Undergraduate Programme Leader  2  3 EFFECTS & AVOIDANCE OF LIGHTNING STRIKES ON AIRCRAFT  4  Author’s Declaration Statement 1 This work has not previously been presented in any form to Glyndŵr University or at any other institutional body whether for assessment or for any other purposes. Save for any express acknowledgements, references, and/or bibliographies cited in the work, I confirm that the intellectual content of the work is the result of my own efforts and no other person. Statement 2 It is acknowledged that the author of this work shall own the copyright. However, by submitting this copyright work for assessment, the author grants to the University a perpetual royalty-free license to do all or any of those things referred to in section 16(I) of the copyright, designs, and patents act 1988 (viz: to copy work; to issue copies to the public; to perform or show or play the work in public, to broadcast the work or make an adaptation of the work). Signed: Date:      5 ABSTRACT  The following report is based upon studying the effects of the lightning strikes on aircraft, attending to its direct and indirect effects. To achieve this above, a number of key stages have been completed, including research and testing procedures, which then are taken into account for doing the project. The research is about the effects, tests and standards and materials on aircraft, such as composite materials, which are really used nowadays for manufacturing aircrafts.                    6 ACKNOWLEDGEMENTS  I would like to take this opportunity to pay my upmost gratitude to my supervisor, Cedric Belloc, for the constant help, knowledge and guidance throughout the duration of the project. I would also like to thank Olivier Duriex, for lending me carbon fibre for doing the tests and give me information about composites. Last, I would like to thank my family for giving me the opportunity to study this degree.  7 TABLE OF CONTENTS AUTHOR’S DECLARATION...................................................................................................... iv4 ABSTRACT................................................................................................................................. v5 ACKNOWLEDGEMENTS.......................................................................................................... vi6 LIST OF FIGURES .....................................................................................................................11 LIST OF TABLES .......................................................................................................................15 CHAPTER 1. INTRODUCTION..................................................................................................17 1.1 Background to Proposal....................................................................................................17 1.2 Aims .................................................................................................................................18 1.3 Objectives .........................................................................................................................18 1.4 Overview ...........................................................................................................................19 1.5 Planning ............................................................................................................................20 1.6 References........................................................................................................................ 21 CHAPTER 2. WEATHER CONDITIONS FOR AIRCRAFT .......................................................22 2.1 Thunderstorms..................................................................................................................22 2.1.1 Single-cell thunderstorm.............................................................................................24 2.1.2 Isolated multi-cell cluster thunderstorm......................................................................25 2.1.3 Multi-cell squall line thunderstorm ..............................................................................25 2.1.4 Supercell thunderstorm ..............................................................................................26 2.2 Lightning............................................................................................................................26 2.2.1 Introduction.................................................................................................................26 2.2.2 Types of lightning .......................................................................................................27 2.2.2.1 Cloud-to-ground lightning.....................................................................................27 2.2.2.2 Ground-to-cloud lightning.....................................................................................29 2.2.2.3 Cloud-to-cloud lightning .......................................................................................30 2.2.2.4 Other different types of lightning..........................................................................32 2.3 References........................................................................................................................ 35 CHAPTER 3. WEATHER RADAR SYSTEMS IN AIRCRAFT ....................................................37 3.1 Radar ................................................................................................................................37 3.2 Weather radar ...................................................................................................................37 3.3 Stormscope.......................................................................................................................39 3.4 Strikefinder........................................................................................................................39 3.4 References........................................................................................................................ 40 CHAPTER 4. EFFECTS OF LIGHTNING STRIKES IN AIRCRAFT...........................................41 4.1 Introduction .......................................................................................................................41 4.1.1 Defining terms ............................................................................................................41  8 4.1.2 Measurements............................................................................................................42 4.2 Categories of lightning ......................................................................................................42 4.3 Zoning ...............................................................................................................................43 4.4 Effects on aircraft due to lightning.....................................................................................45 4.5 Fatal accidents due to lightning strikes .............................................................................45 4.6 References........................................................................................................................ 49 CHAPTER 5. PROTECTION AND LIGHTNING TESTING ........................................................50 5.1 Faraday cage ....................................................................................................................50 5.2 New techniques. Protection ..............................................................................................51 5.2.1 Surface protection ......................................................................................................53 5.2.1.1 Diverters...............................................................................................................53 5.2.1.2 Static Wicks .........................................................................................................54 5.2.1.3 Wing tips ..............................................................................................................56 5.2.1.4 Solid bars.............................................................................................................57 5.2.2 Fuel tank.....................................................................................................................57 5.3 Lightning tests...................................................................................................................59 5.3.1 Visual Lightning Test Procedures ..................................................................................59 5.3.2 Indirect effects Lightning Tests ......................................................................................60 5.4 Applicable standards.........................................................................................................60 5.5 References........................................................................................................................ 61 CHAPTER 6. AIRCRAFT DESIGN.............................................................................................63 6.1 Materials used on aircraft..................................................................................................63 6.2 Aircraft components ..........................................................................................................63 6.2.1 Aluminium and magnesium alloys..............................................................................65 6.2.2 Steels.......................................................................................................................... 67 6.2.3 Titanium and its alloys................................................................................................68 6.2.4 Nickel alloys (Nimonics) .............................................................................................68 6.2.5 Plastics and composites.............................................................................................69 6.2.6 Glass ..........................................................................................................................71 6.3 Composites on aircraft ......................................................................................................72 6.3.1 Structure of composites..............................................................................................72 6.3.2 Evolution from aluminium to composites on Airbus....................................................74 6.3.3 Comparison in use of composites ..............................................................................78 6.4 References........................................................................................................................ 80 CHAPTER 7. TESTS ON MATERIALS ......................................................................................82 7.1 Introduction ......................................................................................................................82 7.2 Tests .................................................................................................................................86  9 7.3 Results and discussion .....................................................................................................87 7.3 References........................................................................................................................ 97 CHAPTER 8. CONCLUSION......................................................................................................98 8.1 Overall conclusion.............................................................................................................98 8.2 Further work......................................................................................................................99 APPENDIX A. ATMOSPHERE.................................................................................................100 A.1 Atmosphere ....................................................................................................................100 A.1.1 Troposphere.............................................................................................................101 A.1.2 Stratosphere.............................................................................................................101 A.1.3 Mesosphere .............................................................................................................102 A.1.4 Thermosphere..........................................................................................................102 A.2 References .....................................................................................................................103 APPENDIX B. LIGHTNING STRIKE REPORTING FORM....................................................... 104 B.1 Reporting form................................................................................................................104 B.2 Refereces .......................................................................................................................104 APPENDIX C. LIGHTNING STRIKE INSPECTION AS PER AIRBUS..................................... 108 C.1 Inspection .......................................................................................................................108 C.2. References ....................................................................................................................118 APPENDIX D. INDIRECT EFFECTS LIGHTNING TESTS ......................................................119 D.1 Lightning tests ................................................................................................................119 D.2. References ....................................................................................................................125 APPENDIX E. APPLICABLE STANDARS................................................................................126 E.1 Applicable standards ......................................................................................................126 E.2 RTCA DO-160 ................................................................................................................129 E.3 European Organisation for Civil Aviation Equipment (EUROCAE).................................131 E.4 US Department of Transportation, Federal Aviation Authority (FAA) .............................131 E.5 International Standards Organisation (ISO)....................................................................132 E.6 Equivalences in FAA and EUROCAE............................................................................ 132 E.7 Standard comparison......................................................................................................133 E.8 References .....................................................................................................................133 APPENDIX F. FAA REGULATIONS.........................................................................................134 F.1 Reference .......................................................................................................................135 APPENDIX G. TESTS ..............................................................................................................136 G.1 Carbon Fibre ..................................................................................................................136 G.2 Galvanized carbon steel.................................................................................................137 G.3 Stainless steel 304 ......................................................................................................... 138 G.4 Aluminium.......................................................................................................................140  16 Appendix G Table G.1.1 Carbon Fibre Test Results Table G.2.1 Galvanized Carbon Steel Results Table G.3.1 Typical chemical composition for 304 stainless steel alloys Table G.3.2 Stainless Steel 304 Results Table G.4.1 Aluminium Test Results Table G.5.1 Bronze Test Results Table G.6.1 Ungalvanized Carbon Steel Test Results Table G.7.1 Copper Test Results Table G.8.1 Glass Fibre 1 Test Results Table G.9.1 Wood Test Results Table G.10.1 Polyethylene Test Results Table G.11.1 Foam Test Results Table G.12.1 Epoxy resin Test Results Table G.13.1 Semi-conducting self-fusing tape Test Results Table G.14.1 Glass Fibre 2 Test Results Table G.15.1 Plastic Test Results Table G.16.1 Glass Test Results          17 CHAPTER 1. INTRODUCTION 1.1 Background to Proposal Weather conditions in a flight route are important since they involve passenger’s safety. Thunderstorms are accompanied with lightning, squalls and sometimes, hail and tornadoes. Storms are an atmospheric phenomenon produced by cumulonimbus. They built up when the atmosphere is unstable. This occurs when the air is colder than usual in the highest part of the troposphere1 (it happens when a cold front passes or in a low pressure situation). Lightning is associated with thunderstorms. A light is a static electricity discharge generated in the cloud. The effects caused in the aircraft due to lightning are divided into direct and indirect effects: • Direct effects: Any physical damage to the aircraft and/or electrical/electronic systems due to the direct attachment of the lightning channel. This includes tearing, bending, burning, vaporization or blasting of aircraft surfaces/structures and damage to electrical/electronic systems. • Indirect effects: Voltage and/or current transients induced by lightning in aircraft electrical wiring which can produce upset and/or damage to component within electrical/electronic systems. [1] Nowadays, storms and lightning strikes are observed thanks to a device that can detect them. This is based on radar systems. Weather radar system allows the pilot to identify the weather conditions attending o the colour showed on the display. The strikefinder is a recently developed device that, being used with a stormscope, it gives more accurate information about lightning strikes. Besides, composite materials also help to avoid electrical discharges. They are based on fibres, meaning that stiffness and strength in all directions are not the same. These materials have advantages and disadvantages to take into account related to lightning strikes.   1 Troposphere: It is the lower part of the atmosphere, extending from the surface up to a height varying about 7 to 9 km at polar regions to approximately 17 km in tropics. The troposphere is characterized by decreasing temperature with height, appreciable vertical wind motion, appreciable water vapor content, and weather. [2]  18 1.2 Aims To research and investigate: a) Lightning effects on aircraft and weather radar systems; b) Design and testing of aircraft in order to avoid electrical discharges; c) Lightning simulation. 1.3 Objectives In order to achieve the aim, a set of objectives have been carried out as follows: ‐ To research atmospheric phenomena; ‐ To be familiar with the layers of the atmosphere; ‐ To do a research on thunderstorms; ‐ To investigate lightning; ‐ To be familiar with radar systems; ‐ To look information about weather radar system; ‐ To investigate Stormscope and Strikefinder; ‐ To study negative effects of electrical discharges on aircraft; ‐ To be familiar with electrical principles; ‐ To do a research of lightning testing standards; ‐ To study aircraft’s design; ‐ To research on metallic and non-metallic materials; ‐ To study the advantages and disadvantages of composite materials; ‐ To be familiar with the simulation software.  19 1.4 Overview Weather conditions in a flight route are important since they involve passenger’s safety. Thunderstorms are accompanied with lightning, squalls and sometimes, hail and tornadoes. Storms are an atmospheric phenomenon produced by cumulonimbus. They built up when the atmosphere is unstable. This occurs when the air is colder than usual in the highest part of the troposphere (it happens when a cold front passes or in a low pressure situation). Losses in aviation due to lightning strikes are noticeable. The most dangerous moment for an aircraft is while taking off and landing. While doing any of these two actions, the aircraft is located under the thunderstorm that is the place in which occurs the majority of lightning. Since lightning from the clouds to the ground is the most common, the risk of being struck by lightning in this zone is higher. Besides, some zones of the aircraft are more prone to be struck. However, using non-metallic materials on the aircraft, the risk can be reduced.  20 1.5 Planning  21 1.6 References [1] Niu, M. C. Y. (1992) Composite Airframe Structures. Practical design information and data, pp 362-365, Hong Kong, Conmiliit Press. [2] Troposphere, National Snow and Ice Data Center, [Electronically accessed 10 November 2009] <http://nsidc.org/arcticmet/glossary/troposphere.html>                          22 CHAPTER 2. WEATHER CONDITIONS FOR AIRCRAFT 2.1 Thunderstorms The storms are atmospheric phenomena, produced by cumulonimbus. These clouds are developed when the atmosphere is unstable. This usually occurs when a cold front passes or in situations of low pressure [1]. Storms are developed according to the following process [2] (see Figure 2.1.1): • Earth warming causes an ascending flow of air that gets colder progressively until it is condensed creating small cumulus. • Unlike the good weather, the ascending air flow does not stop and the cloud grows vertically very fast. • The cumulus keeps on growing vertically and it is becoming a storm cloud. Now, the electrical charges start to disorder in the cloud. The top of the cloud will be positive and the bottom will be negative. Inside the cloud, there are drops kept in suspension due to the air flow. • The cumulus has become a cumulonimbus. It can be of 10km height and the temperature in its top can be around -20°C or -30°C. • Now, the earth is colder and it starts raining. Figure 2.1.1 Process of the storm [3]  23 This process can be divided into three stages [4]: developing stage, mature stage and dissipating stage (See Figure 2.1.2, 2.2.3 and 2.1.4). Figure 2.1.2 Developing stage [4] Figure 2.1.3 Mature stage [4] Figure 2.1.4 Dissipating stage [4]  24 Thunderstorms can be classified in four types [5] (see Figure 2.1.5): • Single-cell; • Isolated multicell cluster; • Multicell squall line; • Supercell. Figure 2.1.5 The thunderstorm spectrum [5] 2.1.1 Single-cell thunderstorm The term of single-cell is applied to an isolated thunderstorm with one main draft (see Figure 2.1.1.1). They are more common during summer time and they also occur in winter when cold and unstable air follows the way of a cold front from the sea. “Cell” refers to single air draft. Single-cell thunderstorms are not longer last 20-30 minutes [6].      Figure 2.2.1.1 Single-Cell Thunderstorm [5]  25 2.1.2 Isolated multi-cell cluster thunderstorm This type of thunderstorms is the most common. They consist of a group of cells that move as a single unit, but every cell is in a different stage of the lifecycle of the thunderstorm [7] (see Figure 2.1.2.1). The hazards of this type of thunderstorms are: hail (moderated size), flash flooding and weak tornadoes.       Figure 2.1.2.1 Multi-cell cluster thunderstorm [5] 2.1.3 Multi-cell squall line thunderstorm The multicell line storm (see Figure 2.1.3.1), or squall line, consists of a long line of storms with a continuous well-developed gust front at the leading edge of the line. The line of storms can be solid, or there can be gaps and breaks in the line [7]. These storms can produce small to moderate size hail, heavy rainfall and weak tornadoes. Figure 2.1.3.1 Multi-cell squall line thunderstorm [8]  32 2.2.2.4 Other different types of lightning Dry lightning Dry lightning (see Figure 2.2.2.4.1) is a term in the United States for lightning that occurs with no precipitation at the surface. This type of lightning is the most common natural cause of wildfires [9]. Pyrocumulus clouds produce lightning for the same reason that it is produced by cumulonimbus clouds. When the higher levels of the atmosphere are cooler, and the surface is warmed to extreme temperatures due to a wildfire, volcano, etc, convection will occur, and the convection produces lightning. Therefore, fire can beget dry lightning through the development of more dry thunderstorms which cause more fires [13]. Figure 2.2.2.4.1 Dry Lightning [23] Rocket lightning It is a form of cloud discharge, generally horizontal and at cloud base, with a luminous channel appearing to advance through the air with visually resolvable speed, often intermittently [13] (see Figure 2.2.2.4.2). Figure 2.2.2.4.2 Rocket Lightning [24]  33 Positive lightning Positive lightning (see Figure 2.2.2.4.3) is a type of lightning strike that comes from apparently clear or only slightly cloudy skies; they are also known as "bolts from the blue" because of this trait. Unlike the more common negative lightning, the positive charge is carried by the top of the clouds (generally anvil clouds) rather than the ground. The leader forms in the sky travelling horizontally for several miles before veering to down to meet the negatively charged streamer rising from below. Positive lightning makes up less than 5% of all lightning strikes. During a positive lightning strike, huge quantities of ELF and VLF radio waves are generated [15]. Positive lightning has also been shown to trigger the occurrence of upper atmosphere lightning. It tends to occur more frequently in winter storms, as with thundersnow, and at the end of a thunderstorm [16]. Figure 2.2.2.4.3 Positive Lightning [25] Ball lightning Ball lightning refers to reports of luminous, usually spherical objects which vary from pea-sized to several meters in diameter. It is sometimes associated with thunderstorms, but unlike lightning flashes, which last only a fraction of a second, ball lightning reportedly lasts many seconds. One theory is that ball lightning may be created when lightning strikes silicon in soil, a phenomenon which has been duplicated in laboratory testing. Natural ball lightning appears infrequently and unpredictably [26].  34 Upper-atmospheric lightning [13] The upper-atmospheric lightning has sometimes been called megalightning. Sprites Sprites are large scale electrical discharges which occur high above a thunderstorm cloud, or cumulonimbus, giving rise to a quite varied range of visual shapes. They are triggered by the discharges of positive lightning between the thundercloud and the ground. They often occur in clusters, lying 50 miles (80 km) to 90 miles (145 km) above the Earth's surface. (See Figure 2.2.2.4.4) Blue jets Blue jets differ from sprites in that they project from the top of the cumulonimbus above a thunderstorm, typically in a narrow cone, to the lowest levels of the ionosphere 25 miles (40 km) to 50 miles (80 km) above the earth. They are also brighter than sprites and, as implied by their name, are blue in colour. (See Figure 2.2.2.4.4) Elves Elves often appear as dim, flattened, expanding glows around 250 miles (402 km) in diameter that last for, typically, just one millisecond. They occur in the ionosphere 60 miles (97 km) above the ground over thunderstorms. (See Figure 2.2.2.4.4) Figure 2.2.2.4.4 Upper-atmospheric lightning [13]  35 2.3 References [1] Cumulonimbus cloud, Absolute Astronomy, [Electronically accessed 23 November 2009], <http://www.absoluteastronomy.com/topics/Cumulonimbus_cloud> [2] Lightning, electricalfun.com, [Electronically accessed 4 Dcember 2009], <http://www.electricalfun.com/lightning.htm> [3] Weather tutorial, NASA (National Aeronauticas and Space Administration), [Electronically accessed 27 November 2009], <http://quest.arc.nasa.gov/aero/virtual/demo/weather/tutorial/tutorial5c.html> [4] Understanding Boquete Weather and Cimate , boqueteweather.com, [Electronically accessed 25 November 2009], <http://www.boqueteweather.com/climate_article.htm> [5] National Weather Service, NOAA (National Oceanic and Atmopheric Administration), [Electronically accessed 29 November 2009], <http://www.crh.noaa.gov/lmk/spotter_reference/spotter_slideshow/index.php> [6] Understanding How Thunderstorms Develop, K3JAE’s Weather Station, Updated 30/11/2009, [Electronically accessed 30 November 2009], <http://www.k3jae.com/wxstormdevelopment.php> [7] Thunderstorms, NOAA National Severe Storms Laboratory, [Electronically accessed 4 December 2009], <http://www.nssl.noaa.gov/primer/tstorm/tst_basics.html> [8] Types of thunderstorms, NOAA, Ocena’s Service, [Electronically accessed 3 Dcember 2009], <http://oceanservice.noaa.gov/education/yos/resource/JetStream/tstorms/tstrmtypes.htm> [9] Thunderstorm, search.com reference, [Electronically accessed 28 Novemeber 2009] http://www.search.com/reference/Thunderstorm [10] What is lightning?, Lightning Physics, [Electronically accessed 29 November 2009], <http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/kristina_smith/description.html> [11] Lightning and thunder, FMA Research, [Electronically accessed 1 December 2009], <http://www.fma-research.com/Q&A.htm> [12] Physics of Electrical Storms, Natural Disasters, [Electronically accessed 26 November 2009], <http://library.thinkquest.org/03oct/00758/en/disaster/lightning/physics.html>  36 [13] Staszewski, L. Lightning Phenomenon – Introduction and Basic Information to Understand the Power of Nature, EEEIC, International Conference on Environment and Electrical Engineering, [Electronically accessed 28 November 2009], <http://eeeic.eu/proc/papers/52.pdf> [14] Lightning Types and Classifications, Storm Highway, [Electronically accessed 27 November 2009], <http://wvlightning.com/types.shtml> [15] Lightning, Wikipedia, the free encyclopedia, Updated 28/11/2009, [Electronically accessed 28 November 2009], <http://en.wikipedia.org/wiki/Lightning> [16] Lightning Wild Effects, Rob’s Weather Watch, Updated 04/07/2009, [Electronically accessed 4 December 2009], <http://robsweatherwatch.wordpress.com/> [17] Seven Ways Lightning Can Strike, Scienceray, Updated 01/08/2008, [Electronically accessed 3 December 2009], <http://scienceray.com/earth-sciences/meteorology/seven-ways-lightning-can-strike/> [18] Terror Planet, Open Letters Monthly, [Electronically accessed 2 November 2009], <http://www.openlettersmonthly.com/sept08-terror-planet/> [19] Lightning, Extreme Instability, [Electronically accessed 27 April 2010], <http://www.extremeinstability.com/wp/6371wp.jpg> [20] Silent Intracloud Lightning, Flickr.com, [Electronically accessed 3 December 2009], <http://www.flickr.com/photos/teemu-mantynen/3503875471/> [21] Sheet Lightning over Kalgoorlie, Western Autralia, photo.net, [Electronically accessed 26 April 2010], <http://photo.net/photodb/photo?photo_id=1243176> [22] Heat Lightning, Webshots, [Electronically accessed 27 April 2010], <http://travel.webshots.com/photo/1298317468061533222CMCeCV> [23] Weather Terminology, Fox Weather, [Electronically accessed 27 April 2010], <http://weather.fox.com/Community/Forums/ViewBoardTopicServlet?ForumId=165&TopicId=15 313> [24] Lightning Storms Strikes, Solar Navigator, [Electronically accessed 3 December 2009], <http://www.solarnavigator.net/lightning.htm> [25] Florida Lightning Positive Strike, Florida Lightning, [Electronically accessed 29 November 2009], <http://www.floridalightning.com/images/Florida_Lightning_Positive_Strike_9_2_09.jpg> [26] Ball Lightning, Tameside Paranormal, [Electronically accessed 27 April 2010], <http://www.tamesideparanormal.co.uk/#/ball-lightning/4530946810>  37 CHAPTER 3. WEATHER RADAR SYSTEMS IN AIRCRAFT 3.1 Radar RADAR is the acronym for RAdio Detection And Ranging. Radar is a device that using electromagnetic waves can identify the position, altitude or speed of the object. In this particular case, the radar can identify the speed, altitude, direction and position of the aircraft [1]. Radar systems operate in an echo principle (see Figure 3.1.1): high energy radio waves in pulse form are directed in a beam toward a reflecting target. When the pulse strikes the target, a portion of the pulse is reflected back to the receiving section of the radar system [2]. Figure 3.1.1 Pulse Radar System [3] 3.2 Weather radar The weather radar system of an aircraft is called weather mapping system. This device can detect electrical activity caused by storm conditions. All the information is displayed on the CRT (cathode ray tube) or liquid display screen [4]. The weather mapping systems became as a substitute for the radar systems since the new ones were less expensive than the old ones. In many cases, they are used in conjunction [4]. The advantage of the weather mapping systems is that they can detect thunderstorm that are behind other storms. Thus, a weather mapping systems is like a secondary “back up” weather detection system [4].  38 Weather radar has several modes of operation: - Standby mode - On - Weather / Nav - EFIS - Tilt - Range select - Target alert - Weather alert Colour is added to weather radar displays enhances the storm activity image and provides more effective means to detect severe weather (see Figure 3.2.1 and 3.2.2). The colour shows the intensity [4]: - Black areas: indicate clear weather conditions. - Green areas: indicate light clouds. - Yellow areas: indicate increasing thickness of the weather condition. - Red areas: indicate an extreme weather formation. - Magenta areas: indicate an extreme weather condition (such as hail o thunderstorm) or terrain (cumulo granite, very solid weather) Figure 3.2.1 Weather radar display [5] Figure 3.2.2 Intensity by colours [6] Radar intensity is a way to "see" through rain. A pulse of energy is beamed through a cloud and the amount of echo returned will give the intensity of precipitation. The echo is actually a reflection of the energy and a computer will generate a colour code to indicate the amount of precipitation [6].  39 3.3 Stormscope There is a device that can “see” lightning strikes due to the noise that they produce. Thanks to this, the pilot is able to avoid the hazards of the strikes, such us convective wind shear and turbulence. This device is called Stormscope (see Figure 3.3.1), and it is now produced by B. F. Goodrich Flight System. Stormscope comes in two basic types: the three-part WX-1000-series with a CRT display, and the WX-900, which features a less-expensive super-twist liquid crystal; display (LCD). The WX-900 has two parts with the processor unit collocated in the indicator box. [4] 3.4 Strikefinder Strikefinder is a similar systems developed recently (see Figure 3.4.1). This device also has its processor incorporated within the display case. Its range is similar to that of the WX-100, but it is smaller and easy to install, with the prebuilt harness on which only one end must be terminated. Because of the strikefinder’s compact configuration it is less susceptible to noise interference. In fact, the strikefinder is virtually immune to onboard noise generators. The device is quite light thanks to its orange plasma display flat screen and self-contained processor [4]. It detects and analyzes the electrical activity emanating from thunderstorms within a 200 nautical mile (nm) radius of the aircraft [7]. Figure 3.3.1 Stormscope [8] Figure 3.4.1 Strikefinder [8]  40 3.4 References [1] Radar, Fact-Index, [Electronically accessed 7 December 2009], <http://www.fact-index.com/r/ra/radar.html> [2] Eismin T.K. (1994) Aircraft Electricity and Electronics (5th edn.) pp 333-346, Singapore, Mc Graw Hill [3] Pulse-Doppler Method, Integrated Publishing, Electrical Engineering Training Series, [Electronically accessed 5 December 2009], <]http://www.tpub.com/content/neets/14190/css/14190_41.htm> [4] Maher, E.R, (1994) Pilot’s avionics survival guide, pp177-178, U.S.A., TAB. [5] Product Display, Noblis, [Electronically accessed 27 April 2010], <http://www.noblis.org/MissionAreas/oas/Services/WeatherFutures/PublishingImages/Pro duct_display_crop1.jpg> [6] An Introduction to Weather Map Symbols and Terminology, about.com, [Electronically accessed 13 December 2009], <http://weather.about.com/od/forecastingtechniques/ss/mapsymbols_7.htm> [7] Strike Finder, Digital Weather Avoidance System, Aircraft Spruce & Specialty Co., Worldwide Distributor of Aircraft Parts and Pilot Supplies, [Electronically accessed 22 December 2009], <http://www.aircraftspruce.com/catalog/avpages/strikefinder.php> [8] Lightning Detection, Causey Aviation, [Electronically accessed 19 December 2009], <http://www.causeyaviation.com/lightning.htm>            41 CHAPTER 4. EFFECTS OF LIGHTNING STRIKES IN AIRCRAFT 4.1 Introduction In the 1980s, it was demonstrated that most of the lightning strikes to airplanes (as many as 90%) are created by the planes themselves since they fly through clouds charged heavily (it means that they are prone to produce lightning). However, in the other 10%, airplanes fly into a lightning storm or intercept the lightning flash. An idealised concept of aircraft lightning protection would be to have the entire exterior surface highly conductive and electrically continuous (All sides must be connected to each other and there can’t be any large windows [1]). 4.1.1 Defining terms Terms commonly used to describe lightning strikes are given below: ‐ Attachment point: A point of contact between the lightning flash and the aircraft. [2]. ‐ Coupling: the electromagnetic phenomenon by which currents are induced in an object in a strong electric field [3]. ‐ Corona: a luminous discharge caused by a difference in potential between the aircraft and the surrounding atmosphere [3]. ‐ Lightning Flash: The total lightning event on which charge is transferred from one charge centre to another. It may occur within a cloud, between clouds, or between a cloud and ground. It can consist of or more strikes, plus intermediate or continuing currents [2]. ‐ Lightning leader: The leader is the preliminary breakdown that forms an ionized path for charge to be channeled towards the opposite charge centre. The “stepped” leader advances in a series of short, luminous steps prior to the first return stroke. The “dart” leader reionized the return stroke path in one luminous step prior to each subsequent return stroke in the lightning flash [2]. ‐ Lightning strike: Any attachment of the lightning flash to the aircraft [2]. ‐ Lightning stroke (return stroke) – A lightning current surge that occurs when the lightning leader makes contact with the ground or another charge [2]. ‐ Swept stroke: A series of successive attachments due to sweeping of the flash across the surface of the airplane by the motion of the airplane [2].  48 Comments: Crashed after lightning strike. Source: FI 03.01.1981 (29) 7. 08.02.88 (07.58) Swearingen SA.227AC Metro D-CABB (AC-500) Nurnberger Flugdienst - NFD Occupants: 2 crew + 19 passengers Fatalities: 2 crew + 19 passengers Accident Occurred: Initial Approach Location: Mulheim; nr (Germany) Flight Hannover-Langenhagen APT - Dusseldorf Flight: 108 Comments: The Metro aircraft suffered a lightning strike, following which the electrical system falied. The right wing broke off in an uncontrolled descent and the aircraft disintegrated. 8. 22.06.2000 Shitai, China [12] Wuhan AL Struck by lightning causing the plane to explode and crash 9. 10/10/01 Off Valencia, Spain [12] Flightline Electrical power was lost following a lightning strike. 10. 27/12/02 Anjouan, Comoros Islands [12] Ocean Airlines Struck by lightning causing loss of artificial horizons and gyro compasses.  49 4.6 References [1] Faraday Cage & EMP Protection, The Survivalist Blog, Updated 01/04/2010, [Electronically accessed 15 April 2010], <http://www.thesurvivalistblog.net/2010/04/faraday-cage-emp-protection.html> [2] Niu, M. C. Y. (1992) Composite Airframe Structures. Practical design information and data, p365, Hong Kong, Conmiliit Press. [3] IEEE Spectrum (1988), Aircraft jolts from lightning bolts, p34, Electromagnetic Applications, [Electronically accessed 7 January 2010], <http://www.electromagneticapplications.com/pdf/IEEEJolt.pdf> [4] IEEE Spectrum (1988), Aircraft jolts from lightning bolts, p36, Electromagnetic Applications, [Electronically accessed 7 January 2010], http://www.electromagneticapplications.com/pdf/IEEEJolt.pdf [5] United Kingdom, Ministry of defence, Tench, K. (15/09/??) Defence Standard 59-411 part 2 Issue 1 Draft, p9, Precompliance.com, [Electronically accessed 18 January 2010], <http://www.precompliance.com/EMCBK/upload/bookfile/UK_MIL_STD_59_411_Part_2.pdf> [6] UK Civil Aviation Authority, AIL/0014, Issue 2 (10/09/2001), Airworthiness Information Leaflet, Lightning Strike Hazards on Light Aircraft, p2, faa.gov Federal Aviation Administration, [Electronically accessed 12 January 2010], <http://www.caa.co.uk/docs/33/AIL0014.PDF> [7] U.S. Department of Transportation Federal Aviation Administration, O’Loughlin, J.B. and Skinner S.R. (August 2004) DOT/FAA/AR-047/13 General Aviation Lightning Strike Report and Protection Level Study, Appendix C-2, faa.gov Federal Aviation Administration, [Electronically accessed 10 January 2010], <http://www.tc.faa.gov/its/worldpac/techrpt/ar04-13.pdf> [8] Lightning Effects on Aircraft, AHE Adavanced Helicopter Electromagnetics, [Electronically accessed 26 December 2009], <http://www.fulton.asu.edu/~balanis/AHE/Lightning.html> [9] How aircraft is protected from lightning? Lightning Technologies, [Electronically accessed 2 January 2010], <http://www.lightningtech.com/d~ta/faq1.html> [10] Aviation Losses from Lightning Strikes, NLSI National Lightning Safety Institute, [Electronically accessed 20 December 2009], <http://www.lightningsafety.com/nlsi_lls/avaition_losses.html> [11] MSL (Aviation), Mimi. Hu, [Electronically accessed 9 March 2010], <http://en.mimi.hu/aviation/msl.html> [12] Accident statistics, Plane Crash Info, [Electronically accessed 15 March 2010], <http://www.planecrashinfo.com/cause.htm>   50 CHAPTER 5. PROTECTION AND LIGHTNING TESTING 5.1 Faraday cage A Faraday Cage is a shell made of an electrical conducting material. If there is a large electric field outside the conducting shell, the electric charges on the shell will move around and redistribute themselves until the electrical field inside the shell is zero (see Figure 5.1.1). Therefore, a Faraday Cage acts as a shield for large electric fields or for electromagnetic waves. It is an application of Gauss's law, one of Maxwell's equations. Gauss's law describes the distribution of electrical charge on a conducting form, such as a sphere, a plane, a torus, etc [1]. Even if a Faraday cage experiences the large electric field of a lightning strike, the electric field inside the Faraday cage will be zero. Hence a Faraday cage makes an effective shield against lightning strikes [2]. Figure 5.1.1 Principles of Faraday cages [3] An aircraft with a fuselage that is made of aluminum or any other electrically conducting metal will form a Faraday cage around the pilots and passengers [2]. In aircraft, the fuselage is used as the common voltage ground and is referenced as 0volts. Then any circuits that need voltage take the voltage from the aircraft’s generators referenced to the fuselage, regardless of the actual voltage of the fuselage above earth ground [4]. If the plane flies through an electrical storm and is struck by lightning, the electric field inside the hollow metal fuselage remains zero and the occupants are safe, as long as they are not in electrical contact with the exterior. For the electric field to be zero inside the Faraday cage, the electric charges must rearrange themselves on the surface. These moving charges on the outside of the Faraday cage can  51 produce strong electric currents. Hence the occupants of the airplane should not be in electrical contact with the outside shell of the aircraft [2] (see Figure 5.1.2). Figure 5.1.2 Faraday cage and passengers [5] 5.2 New techniques. Protection The objectives of the lightning protection design direct effects are [6]: 1. Prevent catastrophic structural damage. 2. Prevent hazardous electrical shocks to occupants. 3. Prevent loss of aircraft flight control capability. 4. Prevent ignition of fuel vapours. The regulations state that compliance can be shown by either bonding components (electrical connections among components sufficient to withstand lightning currents) to the airframe or by designing components so that a strike will not endanger the airframe. The steps in protection design and certification may vary somewhat from one program to another, but most programs include the following basic steps [6]: • Step a - Establish the Lightning Zone Locations • Step b - Identify Systems and Components that are Performing Flight Critical or Essential Functions • Step c - Establish Protection Criteria • Step d - Design Protection • Step e - Verify Protection Adequacy  52 When the aircraft fails due to lightning strikes, the failure condition can be divided into 3 categories (see Table 5.2.1) [7]: Table 5.2.1 Lightning Failure conditions and certification Levels [7] FAILURE CONDITION DEFINITION FAILURE CONDITION SYSTEM LIGHTNING CERTIFICATION LEVEL Failure conditions that prevent continued safe flight and landing. The definition is: failure conditions that are expected to result in multiple fatalities of the occupants, or incapacitation or fatal injury to a flight crewmember normally with the loss of the airplane. Catastrophic A Failure conditions that reduce the aircraft’s or the crew’s ability to cope with adverse operating conditions that would: • Greatly reduce safety margins or functional abilities; • Cause physical distress or larger workload that could prevent flight crew members from performing their tasks accurately or completely; or • Seriously injure a few occupants Hazardous / Severe-Major B Failure conditions that reduce the aircraft’s or the crew’s ability to cope with adverse operating conditions that would, for example: • Significantly reduce safety margins or functional abilities; • Significantly increase crew workload or decrease crew efficiency; or • Cause discomfort to occupants, possibly including injuries. Major C The protection can be divided into three different parts: ‐ Skin and surface protection ‐ Protection of radomes and antenna fairings o Solid bar diverters o Segmented diverters  53 ‐ Protection of composites with conductive applications o Thermal sprayed metals o Woven wire fabrics o Solid metal foils o Expanded metal foils o Aluminized fibreglass o Conductive paints o Metalized fabrics o Interwoven wires [6] 5.2.1 Surface protection 5.2.1.1 Diverters This protection consists of a segmented diverter strip which provides maximum multiple strike protection with negligible effect on RF patterns characteristics. Attached to an aircraft’s radome (see Figure 5.2.1.1.1), the system allows a lightning stroke to travel directly to ground in an ionized channel created in the air above the diverter strip (see Figure 5.2.1.1.2). [8] Figure 5.2.1.1.1 Diverter stripes Figure 5.2.1.1.2 Ionized channel above on the nose [9] the diverter [9] The small diameter of the disc segments (1/10 wavelength or less at X band2) makes the strip compatible with radar systems (see Figure 5.2.1.1.3)   2 X band: is a segment of the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of X-band is rather indefinitely set at approximately 7.0 to 11.2 gigahertz (GHz). In radar engineering, the frequency range is specified at 8.0 to 12.0 GHz. [10]  54 Figure 5.2.1.1.3 Lightning Diverter Stripes [8] 5.2.1.2 Static Wicks Static wicks are small pieces of metal connected electrically to the frame of the airplane on the tail and wings (see Figures 5.2.1.2.1 and 5.2.1.2.2). The static charges that build up on an aircraft during flight tend to accumulate near sharp edges like the trailing edges of wings and tail surfaces. The purpose of static wicks is to provide a conductive path for these excess electrons to flow or "leak" from the aircraft back into the atmosphere. This transfer of electrons reduces the charge on the plane's skin and structure [11]. The wicks are composed of hundreds of individual carbon fibres wrapped into a cylinder around 7.6 to 20.3cm long and about the diameter of a soda straw. Each fibre ends in a sharp point to create a strong gradient in the local electrical field. This gradient attracts the static charge and encourages the electrons to flow off the aircraft and back into the atmosphere. Instead of an ionized corona building up on vital communication antennas, the electrical charges find these wicks more attractive [11]. Static discharge wicks also provide other important safety benefits. In the event of a lightning strike, a plane is designed to conduct the excess electricity through its skin and structure to the wicks to be safely discharged back into the atmosphere [11].  55 Figure 5.2.1.2.1 Static Wicks on Airbus A320 [11] Figure 5.2.1.2.2 Static Wick on a Boeing 737 [11]  56 5.2.1.3 Wing tips Wing must be protected since they are prone to be stricken by a lightning (see Figure 5.2.1.3.1). Figure 5.2.1.3.1 Protection of the wing tip [12]  57 5.2.1.4 Solid bars Nose of aircrafts is one of the most important parts since it is the place where the antenna and radar (radome) are located (see Figure 5.2.1.4.1). Figure 5.2.1.4.1 Protection of nose cone and radome [12] 5.2.2 Fuel tank To ensure the protection of the tank (see Figures 5.2.2.1 and 5.2.2.2), some aspects have to be taken into account since even a tiny spark could be disastrous. Extreme precautions are taken to assure that lightning currents cannot cause sparks in any portion of an aircraft's fuel system. The aircraft skin around the fuel tanks must be thick enough to withstand a burn through. All the structural joints and fasteners must be tightly designed to prevent sparks as lightning current passes from one section to another. Access doors, fuel filler caps and any vents must be designed and tested to withstand lightning. All the pipes and fuel lines that carry fuel to the engines, and the engines themselves, must be verified to be protected against lightning. In addition, new fuels that produce less explosive vapours are now widely used. [13]  64 consideration, however. Stiffness of the material is often as important as its strength, and other factors need to be considered as well [3]: ‐ The material must be consistent and predictable in its properties, so that it can be known what behaviour to expect from it. All materials vary slightly in their basic properties, so it is normal to take the lowest or worst properties, plus an appropriate factor of safety, when using them in design. This gives a reasonable guarantee that the material properties will not be worse than the specified properties [3]. ‐ It should ideally be homogeneous (having the same properties in all parts and in all directions), although the way a particular material is processed may mean this is not possible. Aluminium alloys are frequently rolled to produce plate and thin sheets, and this means the material properties may be different in different in different directions, but plate does not. Of the properties are affected in his way, the final properties must be predictable and the rolling direction clearly marked on the plate, to leave the material in a useful state [3]. ‐ Metals must not suffer serious deterioration from corrosion caused by exposure to the weather, sea water or any chemicals that they come into contact with. The effect of stress is likely to accelerate the effects of corrosion. Similarly, non-metals should not be prone to significant degradation under these environments [4]. ‐ It should be non-flammable or of low flammability (magnesium burns fiercely when exposed to fire, but needs very high temperature to ignite it). It should be present no other safety hazard, such as toxicity, in use, manufacture or repair [3]. ‐ It should be readily available and at reasonable cost, and should be suitable for manufacturing using standard processes. Where a material’s properties are particularly useful, new processes can sometimes be devised to make its use more practical. ‐ It should not be highly susceptible to fatigue, or must be used at stress levels low enough to ensure an acceptable life [3]. ‐ It must have good stiffness for a given weight [4]. ‐ It must retain adequate strength at the temperatures to which it will be subjected, particularly with materials used in supersonic aircraft, or certain regions of the aircraft [4]. So these requirements limit the types of materials used in airframes, but there are still many options available to the designer. Usually, the particular needs lead directly to one or a small group of materials, but new alloys and new ways of working can change the situation. The following groups of materials meet the requirements listed above, and are used for the main structure of an airframe [4]: ‐ Aluminium and magnesium alloys (light alloys); ‐ Steels;  65 ‐ Titanium and titanium alloys; ‐ Nickel alloys; ‐ Plastics and composites. 6.2.1 Aluminium and magnesium alloys Pure aluminium and pure magnesium are completely unsuitable as structural materials for airframes, because they have very low strength. However, when alloyed (chemically mixed) with each other metals, their strength is vastly improved, and they form the most widely used group of airframe materials. Alloying metals include zinc, copper, manganese, silicon and lithium, and may be used singly or in combination (see Table 6.2.1.1). There are very many different variations, each having different properties and so suited to different uses [5]. Magnesium alloys are very prone to attack by sea water, and their use in carrier-based aircraft is generally avoided. Aluminium alloys, although denser than magnesium alloys, are much less prone to chemical attack, and are cheaper, so are more widely used [5]. 2024 Alloy 2024 alloy, known as duralumin, consist of 93.5% aluminium, 4.4% copper, 1.5% manganese and 0.6% magnesium, and is the most widely used of all materials in aircraft structures [5]. Aluminium alloys are more prone to corrosion than pure aluminium, so pure aluminium is often rolled onto the surfaces of its alloys to form a protective layer. The process is known as cladding, and sheets of alloy treated like this are known as clad sheets or Al-clad. Another common means of protecting aluminium alloys is anodising (conversion of the surface layer to a form which is more corrosion-resistant by and electro-chemical process) [5]. Aluminium-lithium alloys are superior to aluminium-zinc and aluminium-copper alloys in strength and stiffness so can be used to save weight. Their use is limited because they are around three times as expensive [5]. SPS alloys An interesting property which certain aluminium alloys share with titanium is that they can be super-plastically formed (SPF). When the material is heated to a certain temperature, far below its melting point, is capable of being stretched by several times its own length without tearing or local thinning. It can then be deformed, using an inert gas such as argon, to fill a mould and take its shape exactly, with no spring-back when the pressure is released. There are various techniques based on this property, which can be used to make extremely complicated shapes accurately and with minimum weight. The high initial cost of tooling means SPF is limited to  66 certain high-cost items, and it is not yet suited to mass production. Items such as pressure vessels, small tanks and reservoirs may be made using this technique [5]. Advantages of aluminium and magnesium alloys [5] ‐ High strength-to-weight ratios; ‐ A wide range of different alloys, to suit a range of different uses; ‐ Low density, so greater bulk form same weight means they can be used in a greater thickness than denser materials, and thus are less prone to local buckling; this applies to magnesium alloys even more than aluminium alloys; ‐ Available in many standard forms (sheet, plate, tube, bar, extrusions); ‐ Aluminium alloys are easy to work after simple heat treatment; ‐ Can be super-plastically formed (certain aluminium alloys only). Disadvantages [5] ‐ Prone to corrosion, so need protective finishes, particularly magnesium alloys; ‐ Many alloys have limited strength, especially at elevated temperatures; ‐ Magnesium alloys have low strength (but high strength-to-weight ratio); ‐ No fatigue limit. Table 6.2.1.1Details of aluminium alloys [4] Alloy Designation Type/Composition Application/Description 1000 series Min. 99.0% Al Little use 2000 series Al-Copper Most common type in general use (good fatigue life and fracture toughness) 5000 series Al- Magnesium Low density, susceptible to corrosion 6000 series Al-Magnesium-Silicon Lower strength than 2000 series, weldable Al-Zinc High strength, but poor fatigue performance 7000 series Al-Lithium Superior strength and stiffness to other Al alloys, lower density, superior fatigue performance: expensive  67 6.2.2 Steels Steel is an alloy of pure iron and carbon (except in stainless steels), with a wide range of other materials. In addition to carbon, steels may contain chromium, nickel and titanium. Steels can be produced with a wide range of properties, ranging from extremely hard and brittle to very soft and ductile (able to be bent and stretched). Many steels are prone to corrosion, including those which have the highest strength. By excluding carbon from the composition, it is possible to produce stainless steel, which does not corrode easily. However, even stainless steels should not be considered totally corrosion-resistant.; they may corrode in certain circumstances. Other steels may be protected by plating with another metal, such as zinc or cadmium, although cadmium is used less in modern applications because it is toxic [4]. All steels share one property, they are dense. Steel finds most usage where its strength can be used to best advantage, for instance where space is limited, or where its hardness and toughness are needed. The most common use is in bolts, shafts and bearing surfaces. It has one more advantage: it performs much better at higher temperature than many other materials [4]. Advantages of steel [4] ‐ Cheap and readily available; ‐ Consistent strength; ‐ Wide range of properties available by suitable choice of alloys and heat treatment; ‐ High strength useful where space is limited; ‐ Some stainless steels are highly resistant to corrosion; ‐ High-tensile steels have SWR; ‐ Hard surface is resistant to wear; ‐ Suitable for use at higher temperatures than light alloys; ‐ Most steels easily joined by welding; ‐ Very good electrical and magnetic screening; ‐ Shows a fatigue limit. Disadvantages [4] ‐ Poor strength-to-weight ratio except high tensile alloys; ‐ Dense, so care must be taken not to use very thin sections, or buckling may result; ‐ Most steels very prone to corrosion.  68 6.2.3 Titanium and its alloys Titanium and its alloys were little used before the 1950s, but are becoming more widely used now, despite their high cost. Properties are very similar to steel, but they have a superior strength-to-weight ratio. They are widely used in engine component, such as jet pipes and compressor blades, and other components that are subject to high temperatures. Titanium and its alloys can be quite difficult to machine, and suffer from high degree of spring-back when formed. Many alloys need to be formed at high temperatures, typically over 500⁰C. Like some aluminium alloys, titanium can be super-plastically formed, allowing very strong and light items, such as pressure vessels, to be made. Titanium also has another related property, that it can undergo diffusion bonding. At elevated temperature (but far below the melting point), two pieces of titanium forced together under high pressure will fuse and become a single piece. In some ways this is similar to forge welding, but the process takes place at lower temperatures. When combined with super-plastic forming, this allows even greater flexibility if design [4]. Advantages of titanium and its alloys [4] ‐ High strength-to-weight ratio; ‐ Maintains its strength at high temperatures; ‐ Higher melting point and lower thermal expansion than other materials; ‐ Can be super-plastically formed and diffusion bonded; ‐ Very high resistance to corrosion, especially from salt water. Disadvantages [4] ‐ Expensive; ‐ Can be difficult to work, especially machining; ‐ Poor electrical and magnetic screening; ‐ Very hard scale forms on the surface at high temperatures. 6.2.4 Nickel alloys (Nimonics) Nickel-based high-temperature alloys (known as nimonic alloys) are used where very high temperatures (up to 1000⁰C) will be experienced. For this reason, they find considerable use inside gas-turbine engines, where temperatures are higher than the melting point of many metals. Nickel-based alloys are heavy and difficult to form, so their use is limited to areas where their properties are essential [4].  69 Advantage of nickel alloys [4] ‐ High strength, maintained up to very high temperature. Disadvantages [4] ‐ Very dense; ‐ Difficult to work with. 6.2.5 Plastics and composites Pure plastics have a little structural use, although it is increasing. However, widespread use is being made of composite structures in aircraft, that is, cloths or tapes of glass, carbon or Kevlar (a trade name for aramid) fibres within a thermosetting resin such as epoxy. Often these materials are made into boards or composite panels, which consist of a sandwich of, for example, carbon fibre/Kevlar honeycomb/carbon fibre. This makes a panel of limited strength, but which is extremely light, giving a strength-to-weight ratio far higher than a pure metal panel [4]. They are often used for making galleys and bulkheads inside aircraft passenger compartment, but are increasingly used for aircraft structures. Composite panel are not exclusively made from plastics and aluminium skins or honeycomb cores are commonly used, either together or with plastics (see Figure 6.2.5.1). Boron fibres are also used. He latest generation of fighter aircraft no emerging have up to 30% of the airframe structure made of composite materials [4]. Figure 6.2.5.1 Honeycomb composite [6] The fact that many composites are based on fires means that the strength and stiffness are not the same in all directions. This is not always a disadvantage since many structures are loaded primarily in one direction. By laying up the fibres mainly in that direction, the best use of the  70 material’s properties can be made. In this way, the structure can be tailored to its usage in the airframe [4]. Many plastic-based composites show lower tolerance of impact damage than metals (for instance from bird strikes) [libro]. Some composites can be quite difficult to repair safely. Kevlar, for example, absorbs water if damaged, which can make it difficult to make a satisfactory repair. In all cases, very carefully repairs are needed, usually requiring heater mats and vacuum pumps [7]. Another problem with the increasing use of composite, in leading edges for example, is that they do not provide electrical or magnetic shielding for cables. High voltages can be induced in the aircraft’s electrical system (see Figure 6.2.5.2), which may cause it to fail, if the aircraft is operating close to strong electromagnetic fields. If the aircraft structure cannot provide enough protection, extra shielding is needed, which adds weight, costs and complexity [4]. However, with all these reservations, composites used carefully can produce great weight savings, and aircraft contain increasing amounts of composite structures [4]. Advantages of composites [4] ‐ Very high strength-to-weight ratio and low weigh (varies between materials); ‐ Non-corrodible (but some materials absorb water if damaged); ‐ Easily available in a wide range of forms; ‐ Can make complex shapes easily; ‐ Directional nature of fibres can be used to produce optimum strength in direction of highest loading; ‐ Low resistance to radar and radio signals is ideal for radomes and antenna covers. Disadvantages [4] ‐ Need special manufacturing, inspection and repair methods; ‐ Some materials prone to impact damage; ‐ Strength and stiffness not the same in all directions; ‐ Poor electrical screening.  71 Figure 6.2.5.2 Aircraft electrical system SCAN [8] 6.2.6 Glass The majority of modern aircraft have cabins pressurized for flight at high altitudes. Windscreens and windows are therefore subjected to loads normal to their midplanes. Glass is frequently the material employed for this purpose in the form of plain laminated plate or heat-strengthened plate. The types of plate glass used in aircraft have a modulus of elasticity between 70,000 and 75,000N/mm2 with a modulus of rupture in bending of 45N/mm2 [9].  72 6.3 Composites on aircraft 6.3.1 Structure of composites Composites consist of two or more materials combined to give a material with properties distinct from the original constituents. They may be naturally occurring, or they may be synthetic. A very significant proportion of polymers are used as composites. Composites can be designed to produce a material with desired combinations of properties such as stiffness, strength and density. Composites consist of a matrix material and a reinforcing material. The matrix and reinforcing materials may be metals, ceramics or polymers, but the composites used in airframe components are fibre reinforced polymer (FRP) matrix composites [10]. Airframe composites also have a relatively high cost, do not yield plastically in regions of high stress concentration and are subject to random property variation due to the nature of composite manufacturing processes [10]. The use of advanced composites in airframe construction has increased substantially over the past few decades. They are used as floor beams, doors, aerodynamic fairings and for control surfaces, such as rudders, elevators and ailerons, due to their low weight and high stiffness. [10] Reinforced material fibres [10] Reinforcing materials for polymer matrix composites are often referred to as fibres and they include (in order of increasing cost): • E-glass; • Aramid, e.g. Kevlar ( see Figure 6.3.1.1); • Carbon; • Alumina; • Silicon carbide; • Boron.  73 Figure 6.3.1.1 Structure of aramid (Kevlar) [10] These fibre materials all have high specific strength and stiffness imparting high strength and stiffness to the composite (see Figure 6.3.1.2). Figure 6.3.1.2 Properties of common reinforcing fibres.[10] The matrix [10] The purpose of the matrix in a polymer composite is to: • Support the reinforcing fibres in the required position; • Transfer load between the fibres; • Increase the toughness of the composite; • Protect the fibres from damage. While the longitudinal tensile properties are dominated by the fibres, the properties of shear, compression and transverse tension are dominated by the matrix properties.  80 6.4 References [1] Rupke, E. (2002) Lightning Direct Effects Handbook, AGATE Advanced General Aviation Transport Experiments, [Electronically accessed 22 December 2009], <http://www.niar.twsu.edu/agate/Documents/Lightning/WP3.1-031027-043.pdf> [2] Wilkinson, R. Chapter 1 Airframe Design Features, RayWilkinson.co.uk, [Electronically accessed 10 March 2010], <http://www.raywilkinson.co.uk/textbook_chapt1.htm> [3] Routledge, J. Aerospace Materials Testing, Enzine Articles, [Electronically accessed 12 Marxh 2010], <http://ezinearticles.com/?Aerospace-Materials-Testing&id=3902986> [4] Wilkinson, R. (1996) Aircraft Structures & Systems, pp 41-49, Singapore, Longman [5] Aerospace Alloys, Aviation-Database, [Electronically accessed 11 March 2010], <http://www.aviation-database.com/Technical_Aviation_Articles/Aerospace-Alloys.html> [6] Honeycomb cores, Formula Schools, [Electronically accessed 29 April 2010], <http://www.formulaschools.com/curriculum/compositesimages/cores2.jpg> [7] Advanced composite repair, Scribd, [Electronically accessed 6 March 2010], <http://www.scribd.com/doc/21391039/ADVANCE-COMPOSITE-REPAIR> [8] Electrical System SCAN, Overtheairwaves.com, [Electronically accessed 16 April 2010], <http://overtheairwaves.com/vol6-2.jpg> [9] Curtis, H.; Filippone A.; Cook, M.; Megson, T.H.G.; Tooley, M.; Wyatt, D.; Jenkinson, L.R.; Marchman, J.; De Florio, F.; and Watkinson, J. (2009) Aerospace Engineering Desk Reference, pp 105-106, U.S.A., Elsevier [10] Polymer Composites, NSW HSC, Charles Sturt University, [Electronically accessed 13 April 2010], <http://www.hsc.csu.edu.au/engineering_studies/aero_eng/2579/polymer_composites.html> [11] Evolucion del Aluminio al Composite, Aire y Espacio, tu blog tecnologico y aeronautico, [Electronically accessed 25 March 2010], <http://www.aireyespacio.com/2009/07/la-evolucion-del-aluminio-al-composite.html > [12] Aircraft composite content over time, Unsilent Generation, [Electronically accessed 19 April 2010], <http://unsilentgeneration.files.wordpress.com/2009/06/pub_gt_aircraft_composite_content_1980-2010_lg1.jpg> [13] A350 Structural Design, Aviation News, [Electronically accessed 22 April 2010], <http://www.aviationnews.eu/blog/wp-content/uploads/2009/12/A350_Layout.gif> [14] Comparison A350 and Boeing 787, Now How Solutions, [Electronically accessed 13 April 2010], <http://www.nowhow.nl/english/images/vliegtuigenvergelijk_plat.jpg>  81 [15] Commercial Aerospace Composites Penetration, Edgar Online, [Electronically accessed 21 April 2010], <http://content.edgar-online.com/edgar_conv_img/2008/03/06/0001104659-08-015912_G75521BCI011.GIF>      82 CHAPTER 7. TESTS ON MATERIALS 7.1 Introduction In order to know the conductivity of a material, some tests can be carried out. Resistance of an object is a measure of its opposition to the passage of a steady electric current (see Equation 7.1.1). Equation 7.1.1 Resistance of a material Where: R = resistance (Ω) ρ = resistivity (Ω·mm2/m) L = length (m) s = section (mm2) Resistivity is a constant that depends on the materials and the temperature. Inverse of resistivity is called conductivity (see Equation 7.1.2). Equation 7.1.2 Conductivity of a material Where: σ = conductivity ( Siemens, S) ρ = resistivity (Ω·m = S-1) When a difference of potential is applied between two points, a charge displacements is observed, defined as electrical current. The materials offer a resistance to the flow of charges, governed by Ohm's Law (see Figure 7.1.1).  83 Figure 7.1.1 Ohm’s Law [1] Depending on the position of the electrodes, current can be conducted mainly by volume or surface material (see Figure 7.1.2). Figure 7.1.2 Differences between electrical current in surface and volume [1] Two different types of resistivity for ESD applications and for semiconductor power cables can be defined: • Surface resistivity (SR) in Ohm (see Figure 7.1.3) • Volume resistivity (VR) in Ohm·cm (see Figure 7.1.4) I =Current (A) V = Potential (V) R = Resistance ( Ω) Volume Conductivity Surface Conductivity Surface Conductivity with its associated component of Volume Conductivity  84 Figure 7.1.3 Surface resistivity test [1] Figure 7.1.4 Two points Volume resistivity test [1] The equations for these tests are: • Surface Resistivity (see Equation 7.1.3): Equation 7.1.3 Surface Resistivity of a material Where: SR= Surface Resistivity (Ohm) R = Resistance (Ohm) L = electrode length (cm) g = electrode gap (cm)  85 • Volume resistivity (see Equation 7.1.4): Equation 7.1.4 Volume Resistivity of a material VR = Volume Resistivity (Ohm·cm) R = Resistance (Ohm) S = Electrode area (cm2) defined as S = W· t L = electrode gap (cm) Knowing this, tests can be carried out. The basic circuit (see Figure 7.1.5) used consists of a DC voltage source (see Figure 7.1.6), a resistance and the material. Figure 7.1.5 Circuit in Electronics Workbench Figure 7.1.6 DC Voltage Source Having the circuit modelled, the measures taken are voltage in the material (VM in volts), the current (I in amps) and the voltage in the resistance (VR in volts) (see Figure 7.1.7).  86 Figure 7.1.7 Measuring devices First thing measured are the resistances. The theoretical values of them are: • R 1 = 4700 Ω • R 2 = 220 Ω • R 3 = 120 Ω • R 4 = 3.3 Ω The real values, measured with the multimeter are: • R 1 = 4720 Ω • R 2 = 210 Ω • R 3 = 120 Ω • R 4 = 3.3 Ω 7.2 Tests Tests have been done using different materials, measuring the voltage and current in the circuit (see Appendix G). These tests have been carried out with the following instruments: • Demestres 260b (see Figure 7.2.1) • Fluke 715 Calibrator (see Figure 7.2.2) • Demestres ST 3600 Figure 7.2.1 Demestres [2] Figure 7.2.2 Fluke [3]  87 7.3 Results and discussion For discussing the results, resistance of the material has to be found. The way to do it is using Ohm’s law. From equation in Figure 7.1.1, the value of the resistance of the material (RM) can be found (see Equation 7.3.1) Equation 7.3.1 Value of RM After calculating the value of the material resistance, surface resistivity and volume resistivity (see Equation 7.3.3) can be found. As for doing the tests, the electrode gap is the same as the electrode length, the surface resistivity is the same as the resistance (see equation 7.3.2). Equation 7.3.2 Surface resistivity in the material Equation 7.3.3 Volume Resistivity in the material For calculating the resistance and resistivity, the worst values will be taken into account, since on manufacturing of aircraft the worst values are taken. Attending to the resistance and resistivity, the smallest values are the worst ones, since they will let flow more electrical charge of the lightning.  88 Test 1 The values of R and VR are calculated in order to know how much current the material conducts (see Table 7.3.1). Table 7.3.1 Values of R and VR for carbon fibre The most restrictive values obtained are: From equation 5: R = 2.92 Ω From equation 7: VR = 0.07381 Ω·cm As the result shows, carbon fibre is a quite conductive material. Test 2 The values of R and VR are calculated in order to know how much current the material conducts (see Table 7.3.2). Table 7.3.2 Values of R and VR for galvanized carbon steel The most restrictive values obtained are: From equation 5: R = 0 Ω From equation 7: VR = 0 Ω·cm As the result shows, galvanized carbon steel is conductive since the opposition it makes to the current is null. 1 2 3 4 5 6 7 8 9 10 VM (V) 0.639 0.612 0.611 0.599 0.589 0.591 0.592 0.567 0.589 0.584 I (A) 0.2 0.2 0.2 0.1 0.1 0.2 0.1 0.2 0.2 0.2 R (Ω) 3.195 3.06 3.055 5.99 5.89 2.955 5.92 2.835 2.945 2.92 VR (Ω·cm) 0.08076 0.07735 0.07722 0.15141 0.14888 0.07469 0.14964 0.07166 0.07444 0.07381 1 2 3 4 5 6 7 8 9 10 VM (V) 0 0 0 0 0 0 0 0 0 0 I (A) 0.1 0.2 0.1 0.2 0.1 0.2 0.2 0.2 0.1 0.1 R (Ω) 0 0 0 0 0 0 0 0 0 0 VR (Ω·cm) 0 0 0 0 0 0 0 0 0 0  89 Test 3 The values of R and VR are calculated in order to know how much current the material conducts (see Table 7.3.3). Table 7.3.3 Values of R and VR for stainless steel 304 The most restrictive values obtained are: From equation 5: R = 0.02 Ω From equation 7: VR = 0.00011 Ω·cm As the result shows, stainless steel 304 is conductive material since the results obtained are around zero ohms. Test 4 The values of R and VR are calculated in order to know how much current the material conducts (see Table 7.3.4). Table 7.3.4 Values of R and VR for aluminium The most restrictive values obtained are: From equation 5: R = 0 Ω From equation 7: VR = 0 Ω·cm As the result shows, aluminium is a highly conductive material since the results for R and VR are zero. 1 2 3 4 5 6 7 8 9 10 VM (V) 0.005 0.004 0.005 0.006 0.01 0.008 0.01 0.01 0.01 0.012 I (A) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 R (Ω) 0.025 0.02 0.025 0.03 0.05 0.04 0.05 0.05 0.05 0.06 VR (Ω·cm) 0.00013 0.00011 0.00013 0.00016 0.00027 0.00021 0.00027 0.00027 0.00027 0.00032 1 2 3 4 5 6 7 8 9 10 VM (V) 0 0 0 0 0 0 0 0 0 0 I (A) 0.2 0.1 0.2 0.2 0.2 0.1 0.2 0.2 0.2 0.2 R (Ω) 0 0 0 0 0 0 0 0 0 0 VR (Ω·cm) 0 0 0 0 0 0 0 0 0 0  96 As the result shows, glass in not a conductive material. From the results obtained it can be said that the resistance is so high that it did not let the current flow through the material. From all the result obtained, the materials tested can be divided into: conducting, semiconducting and non-conducting materials (see Table 7.3.17). Table 7.3.17 Classification of the materials tested CONDUCTING SEMI-CONDUCTING NON CONDUCTING (INSULATING) Galvanized Carbon Steel Stainless Steel 304 Aluminium Bronze Ungalvanized Carbon Steel Copper Carbon Fibre Self-fusing tape Glass Fibre Wood Polyethylene Foam Epoxy Resin Glass Fibre Plastic Glass  97 7.3 References [1] ESD Test, Cabot Corporation, [Electronically accessed 28 April 2010], <http://www.cabotcorp.com/wcm/download/en-us/sb/ESD-Test-Sp1.pdf> [2] Pinza amperimetrica digital Demestres, Electroindustrial.com, [Electronically accessed 29 April 2010], <http://electroindustrial.com/instrumentacion/electropinzas/260.htm> [3] Fluke 715 Calibrador V/mA, Pesa Electronica, Tecnologia Electronica, [Electronically accessed 29 April 2010], <http://www.pesaelectronica.com/product_info.php?currency=US&products_id=83&osCsid=518d9475bd0a94dd1095c56c80b9f39b>  98 CHAPTER 8. CONCLUSION 8.1 Overall conclusion In order to carry out this project a great amount of research has been carried out. This research includes information about weather radar systems, such as the Stormscope and the Strikefinder, the effects of lightning strikes on aircraft, as well as the design of the aircraft to avoid lightning strikes, using materials called composites. After this research, some materials have been tested, in order to know the resistance they will offer to the flow of current. Several objectives have been achieved, acquiring acknowledgement about radar systems, formation of thunderstorms, types of lightning, effects of lightning strikes on aircraft, protection techniques and applicable standards, materials used on aircraft (advantages and disadvantages), composite materials and test on different materials attending to its resistance. Initially, a simulation was going to be done, but unfortunately, it was impossible to do it with any software that the University has, so that, it was changed, and test were carried out. From the result obtained, it can be said that the effects of lightning can be divided into direct and indirect effects. The first ones are related to physical damage of the aircraft structure: melting and deformation of the aircraft skin, explosive vaporization of conductors, or sparks in the fuel systems. These phenomena occur in the zones that are prone to be struck by lightning and damage can be reduced by using devices as: diverted stripes, static wicks or wing tips. The indirect effects affect to electrical or electronic systems due to voltage and/or current transients induced by lightning. To avoid these effects, all the electrical and electronic systems are tested according to the regulating laws. Applicable standards deal with the avoidance of failures related to lightning strikes. These standards test the electrical and electronic devices, as well as the materials used on aircraft. These materials should be electrically continuous to favour the flow of the current through the skin of the aircraft, from the attachment point to the lightning stroke. Some areas as joints or non-conductive composites may require protection. Composite materials are increasingly used as they reduce the weight of the aircraft, but in many cases they are poor conductors of electricity and more sensible to lightning strikes. However, metals are good conducting materials facilitating the lightning path. Regarding the last years, the amount of composites used in aircraft has increased in large. While in the 80s the percentage of composites used in aircraft was about a 5%, in 2010 the percentage has risen up to a 50% for companies as Boeing or Airbus. The last aircraft of Boeing (787) and Airbus (A350) have a 50% of composites in their structure. These materials reduce the weight of the aircraft; however some metals are still used. Accordingly to the test carried out, metals are good conductors while some composites are not. In the tests, it is shown how  99 conducting materials present a very low resistance (around zero or zero) which allows them o conduct the electricity and therefore, the current from a lightning strike will pass through it, and it will leave the material. Other materials are semi-conducting ones, since their resistance is not very high, but it is not zero. On the other side, insulating materials (non-conducting) that do not allow the flow of electrical current were tested. This will end in a burst or a deformation of the material in case of hit by a lightning strike. So that, these materials require special protection in order to avoid the direct effects of lightning strikes. Nowadays, the future of composites on aircraft industry looks pretty good. Using these materials the weight is considerably reduced which ends in a small consumption of fuel. With composite materials, structures can be designed combining the proportion and orientation of the layers in a certain direction, depending on the specific requirements of the structure. Besides, they reduce number of components and fasteners, and there will not be corrosion problem.However, regarding to lightning strikes and its avoidance, some measures have to be taken to prevent the aircraft from suffering damage due to lightning strikes. In my opinion, to do this project has been challenging at the same time as enjoyable. Researching and reading information I had acquire a lot of acknowledgements about the topic, finding really interesting information. At the same time, this helped me to set goals and schedule my time in order to achieve them. In conclusion, I find all this year very satisfactory since I been studying what I really like, enjoying every time spend on it. 8.2 Further work For improvements or future work, the project could be enhanced with: • A research on information about how the use of solar panel in the wing of the aircraft will affect electrical discharges of lightning strikes. • Test the materials with better devices, in order to obtain more accurate results. • A test of materials with a Van der Graaf generator. • A model of an aircraft, including the different materials used on the skin of it in real aircraft and test it. • A simulation of a lightning strike in an aircraft with a suitable software, to see how the current flows through the skin when an aircraft is hit by a lightning strike     100 APPENDIX A. ATMOSPHERE A.1 Atmosphere The atmosphere of the earth consists of layers. These layers are defined by differences on temperature. The names for them are (see Figure A.1.1): • Troposphere • Stratosphere • Mesosphere • Thermosphere Figure A.1.1 Layers of the atmosphere [1] Commercial aircraft flies on the highest part of the troposphere, called tropopause. The tropopause is the boundary between the troposphere and the stratosphere.  101 A.1.1 Troposphere The troposphere (see Figure A.1.1.1) is the lowest layer where weather takes place. It contains almost 75% of the air of the atmosphere. The temperature decreases fairly constant with 1.98ºC per 1000ft (6ºC/km) [2]. The altitude varies from 15km at the equator and 8km at the poles [3]. This layer is capped by the tropopause. Its temperature is about -80ºC over the equator and over the poles is around -48ºC during summer. Figure A.1.1.1 Troposphere [4] A.1.2 Stratosphere The stratosphere (see Figure A.1.2.1) is about 40km thick. It gradually warms with height. The ozone layer is located here (see Figure A.1.2.2). Due to the radiation of the sun, the ozone layer is destroyed and the stratosphere gets warmer. Stratopause is the boundary between stratosphere and mesosphere [5]. Figure A.1.2.1 Stratosphere [4] Figure A.1.2.2 Ozone layer [4]  102 A.1.3 Mesosphere It starts at 50km up to 80 km height [6]. The temperature decreases as you go higher. At the top, called mesopause (boundary between mesosphere and thermosphere), the temperature reaches -90ºC (see Figure A.1.3.1). Figure A.1.3.1 Mesosphere [4] A.1.4 Thermosphere This layer goes from 80km to 300km height (see Figure A.1.4.1). Gas molecules are here bombarded by x-rays from the sun and the ionosphere [7]. This process creates oxygen and nitrogen atoms with positive charge capable of reflection short wave radio waves from radio station on earth. The temperature increases again since it receives ultraviolet radiation from the sun. Figure A.1.4.1 Thermosphere [4]  103 A.2 References [1] Atmosphere layers, Encyclopædia Britannica. 2010. [Electronically accessed 2 December 2009],< http://media-2.web.britannica.com/eb-media/56/97256-004-E3540AD9.jpg> [2] The atmosphere, Transport Canada, Updated 27/11/2008 [Electronically accessed 7 December 2009],<http://www.tc.gc.ca/civilaviation/cam/tp13312-2/section2/atmosphere.htm> [3] Earth’s Atmosphere, The Ramman Scattering, [Electronically accessed 6 December 2009], <http://www.raman-scattering.eu/raman/texts/016_text_6.php> [4] Kiliç, A. Atmosphere, Nature Research, Outdoor Sports and Rescue Society, [Electronically accessed 29 November 2009], <http://www.dask.org.tr/english/want_to_know/meteorology/atmosphere/atmosphere.htm> [5] Atmosphere, The Ozone Hole, [Electronically accessed 29 November 2009], <http://www.theozonehole.com/atmosphere.htm> [6] Earth’s atmosphere, NobleEd News, [Electrically accessed 22 November 2009], <http://www.nobleednews.com/earth's_atmosphere.htm> [7] Earth’s atmosphere, Experimental Aircraft Info [Electronically accessed 22 November 2009], <http://www.experimentalaircraft.info/weather/weather-atmosphere.php>               104 APPENDIX B. LIGHTNING STRIKE REPORTING FORM B.1 Reporting form B.2 Refereces [1] U.S. Department of Transportation Federal Aviation Administration, O’Loughlin, J.B. and Skinner S.R. (August 2004) DOT/FAA/AR-047/13 General Aviation Lightning Strike Report and Protection Level Study, Appendix C-2, faa.gov Federal Aviation Administration, [Electronically accessed 10 January 2010], <http://www.tc.faa.gov/its/worldpac/techrpt/ar04-13.pdf>  105  112 (3) All events reported by the crew or by the PFR must be checked in addition/ conjunction with this inspection. Subtask 05-51-18-481-051 C. Safety Precautions Make sure that the safety devices are installed on the landing gears (Ref. TASK 32-00-00-481-801). Subtask 05-51-18-866-051 D. Extension of the Flight Control Surfaces (1) Extend the flaps and the slats (Ref. TASK 27-50-00-866-801). (2) Extend the spoilers (Ref. TASK 27-60-00-866-801). E. Get Access (1) Open the nose gear doors and install the safety devices (Ref. TASK 32-22-00-010-801). (2) Open the main gear doors and install the safety devices (Ref. TASK 32-12-00-010-801). Subtask 05-51-18-860-051 F. Aircraft Maintenance Configuration (1) Make sure that the electrical circuits are de-energized (Ref. TASK 24-41-00-862-801). (2) Make sure that the hydraulic systems are depressurized (Ref. TASK 29- 00-00-864-804). (3) Put warning notices in the cockpit to tell persons not to operate the systems. (4) Put the adjustable access platform in position. 4 . Procedure NOTE : All the necessary inspections are visual unless the text gives other instructions. Operators can refer to the Non-destructive Testing Manual (NTM) and use non-destructive procedures.  113 ------------------------------------------------------------------------------- |ITEM|INSP| INSPECTION TASKS |PHASE|PHASE|PHASE|INSP|REF.| | |CODE| | 1 | 2 | 3 |SIGN|FIG.| |----|----|---------------------------------------|-----|-----|-----|----|----| |1. | | Inspection of the Radome and the Access Door 121AL (Glide/Slope Antenna access). | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine visually the radome external skin and the lightning diverters for burn marks, change of color, puncturing and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine the access door 121AL (glide/ slope antenna access) for burn marks, puncturing and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |2. | | Inspection of the Windshield, Fixed Windows, Sliding Windows and Window Frames. | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine visually the windshield, fixed windows, sliding windows and the window frames for burn marks, change of color and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |3. | | inspection of the Landing Gear Doors | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine the skin of all landing gear doors for burn marks, change of color, puncturing and delamination. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine the electrical bonding leads for breakage and defective attachment.| | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----|  114 |4. | | Inspection of the Landing Gears. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | | | NOTE: Do these checks if the lightning strike occurred: - when the LG was extended and locked down; - during the extension of the LG. - when you find a through hole during the inspection of the landing | | | | | | ------------------------------------------------------------------------------- |ITEM|INSP| INSPECTION TASKS |PHASE|PHASE|PHASE|INSP|REF.| | |CODE| | 1 | 2 | 3 |SIGN|FIG.| |----|----|---------------------------------------|-----|-----|-----|----|----| | | | gears doors. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine all the landing gears. | X | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | | | (1) Examine the LG structure and the points where it is attached for change of color, burn marks and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | | | (2) Examine the shock absorber for change of color and burn marks. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | | | (3) Examine all the components attached to the landing gear and fully examine the electrical looms and components for a change of color and burn marks. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----|  115 |5. | | Inspection of the Belly Fairing | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine the belly fairing panels (including the wing-to-fuselage fairings) for change of color, burn marks, puncturing and delamination. Examine fairing screws and fasteners for burn marks. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |6. | | Inspection of the Fuselage | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Externally examine all of the fuselage skin including rivets and screws for change of color, burns marks and small holes. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine all the probes, sensors and drain masts and the adjacent area for burn marks and change of color. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | C.| | Examine carefully all the communication and navigation antennas and the adjacent area for burn marks, change of color, puncturing and delamination. | | | | | | ------------------------------------------------------------------------------- |ITEM|INSP| INSPECTION TASKS |PHASE|PHASE|PHASE|INSP|REF.| | |CODE| | 1 | 2 | 3 |SIGN|FIG.| |----|----|---------------------------------------|-----|-----|-----|----|----| R |----|----|---------------------------------------|-----|-----|-----|----|----| | D.| | Examine all exterior lights and adjacent area for burn marks and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | E.| | Examine the APU exhaust for burn marks and change of color. | | | | | |  116 R |----|----|---------------------------------------|-----|-----|-----|----|----| |7. | | Inspection of the Wings | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine the top and bottom skin of the wings and the leading and trailing | | | | | | | | | edges for burn marks, change of color | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine the slats for burn marks and damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | C.| | Examine the flap track fairings for burn marks, change of color, puncturing and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | D.| | Examine the flaps for burn marks, change of color, puncturing and delamination. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | E.| | Examine the spoilers for burn marks, change of color, puncturing and delamination. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | F.| | Examine the ailerons for burn marks, change of color, puncturing and delamination. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | G.| | Examine all the static dischargers for burn marks, damaged tip and breakage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | H.| | Examine the wing tip for burn marks and burn holes. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----|  117 | I.| | Examine the lights on the wing tip for burn marks and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |8. | | Inspection of the Engine Nacelles and | | | | | | |ITEM|INSP| INSPECTION TASKS |PHASE|PHASE|PHASE|INSP|REF.| | |CODE| | 1 | 2 | 3 |SIGN|FIG.| |----|----|---------------------------------------|-----|-----|-----|----|----| | | | the Pylons. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine each air intake, inlet cowl, fan cowl, thrust reverser, exhaust nozzle and the pylon for burn marks, change of color, puncturing and delamination. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |9. | | Inspection of the Vertical Stabilizer | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine all the static dischargers for burn marks, damaged tip and breakage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine the skin of the vertical stabilizer and the rudder (specially the leading and the trailing edges, the rudder surface in the hinge area and the antenna fairings), the fin tip cap, the fin and rudder tip cap lightning diverters for burn marks, change of color, puncturing, delamination and other damage. | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| |10. | | Inspection of the Horizontal | | | | | | | | | Stabilizer | | | | | | R |----|----|---------------------------------------|-----|-----|-----|----|----| | A.| | Examine all the static dischargers for burn marks, damaged tip and breakage. | | | | | |  118 R |----|----|---------------------------------------|-----|-----|-----|----|----| | B.| | Examine the skin of the horizontal stabilizer and elevators (specially the leading and the trailing edge, the elevator surface in the hinge area and the tip) for burn marks, change of color, puncturing, delamination and other damage. | | | | | | C.2. References [1] Aircraft Turbulence and lightning strike damage assessment, Aircraft technology, [Electronically accessed 20 November 2010], <http://www.aircrafttechtrng.com/apps/forums/topics/show/1644365-aircraft-turbulance-and- lightning-strike-damage-assesment?page=last>  119 APPENDIX D. INDIRECT EFFECTS LIGHTNING TESTS D.1 Lightning tests When tests are to be a part of the verification process, plans for each test should be prepared which describe or include the following: purpose of the test; test article description and configuration (including appropriate drawing references); test setup to simulate the electrical aspects of the production installation; applicable lightning zone(s); lightning test method; test voltage or current waveforms to be applied; diagnostic methods; acceptance criteria; and the appropriate schedule(s) and location(s) of proposed test(s). [1] Some procedural steps that should be taken are (FAA3 for U.S. or EASA4 for E.U.): A. Obtain FAA concurrence with test plans. B. Obtain FAA concurrence on details of part conformity of the test article and installation conformity of the test setup. C. Part conformity and installation conformity should be judged from the viewpoint of similarity to the production parts and installation. Development parts and simulated installations are acceptable provided they can be shown to adequately represent the electrical and mechanical features of the production parts and installation for the specific lightning tests. Adequacy should be justified by the applicant and receive concurrence from the FAA. D. Schedule FAA witnessing of the test(s). E. Conduct testing. F. Submit a final test report describing all results. G. Obtain FAA approval of the report. [1] In lightning environmental standards, two simulations can be defined [2]: ‐ Simulation of direct strike current and voltage. ‐ Simulation of the induced currents and voltages within the aircraft resulting from the direct strike.   3 FFA: The Federal Aviation Administration (FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of civil aviation in the U.S. (National Airworthiness Authority) [3] 4 EASA: The European Advertising Standards Alliance (EASA) is the single authoritative voice on advertising self-regulation issues and promotes high ethical standards in commercial communications by means of effective self-regulation, while being mindful of national differences of culture, legal and commercial practice. [4]  120 Lightning current components can be divided into four types of components (see Figure D.1.1) Figure D.1.1 Lightning current components [5] COMPONENT A: Initial Stroke COMPONENT B: Intermediate current Peak amplitude = 200 kA ± 10% Maximum charge transfer = 10 coulombs Action integral = 2 x 106 A2.s ± 20% Average amplitude = 2 kA ± 10 % Time duration ≤ 500 μs COMPONENT C: Continuing current COMPONENT D: Restrike Charge transfer = 200 coulombs ± 20 % Peak amplitude = 100 kA ±10 % Amplitude = 200 - 800 A Action integral = 0,25 x 106 A2.s ± 20% Time duration ≤ 500 μs There are five test levels and six waveforms. Three sequences of pulses are used for induced lightning testing: [6] ‐ Single stroke (SS) ‐ Multiple Stroke (MS) (see Figure D.1.2)  121 Figure D.1.2 Multiple Stroke application of a Waveform [6] ‐ Multiple Burst (MB) (see Figure A.1.3) Figure D.1.3 Multi burst application [6] There are three primary methods of testing aircraft components (see Table D.1.1) [7]: ‐ Pin Injection – This method is used to directly inject the waveform into connector pins of both cables and printed wiring boards. ‐ Cable Bundle Induction – This method uses a coupling transformer to inductively couple the waveform onto the cable bundle. ‐ Ground Injection – This method is often used as an alternate method to inject the waveform onto the ground wire of the unit under test, referenced to the ground plane that is located on the surface of the test table. First Transient Level First Transient 10ms ≤ Δx ≤ 200ms Subsequent Transient Subsequent Transient TRANSIENT (1 & 10 MHz) VT of IL Subsequent Transient Subsequent Transient Subsequent Transient Level 1.5 seconds One first transient followed by thirteen subsequent transients distributed over a period of up to 1.5 seconds VT of IL One burst is 20 transients spaced 50-1000µs Level Time 20 transients30ms ≤ Δx ≤ 300ms  128 2. The components of the installation must be constructed, arranged, and installed so as to ensure their continued safe operation between normal inspections or overhauls; 3. The installation must be accessible for necessary inspections and maintenance; and 4. The major components of the installations must be electrically bonded to the other parts of the airplane. (c) For each powerplant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination failures will jeopardize the safe operation of the airplane except that failure of structural elements need to be considered if the probability of such failure is extremely remote. (d) Each auxiliary power unit installation must meet the applicable provisions of this subpart. • 25.903 (a) Engine type certificate. 1. Each engine must have a type certificate and must meet the applicable requirements of part 34 (Fuel venting and exhaust emission requirements for turbine engine powered airplanes) 2. Each turbine engine must comply with one of the following: (i) Sections 33.76 (bird ingestion), 33.77 (foreign object ingestion - ice) and 33.78 (rain and hail ingestion) of this chapter in effect on December 13, 200, or as subsequent amended; or (ii) Section 33.77 and 33.78 of this chapter in effect on April 13, 2000, or as subsequently amended before December 13, 2000; or (iii) Comply with 33.77 of this chapter in effect on October 31, 1974, or as subsequently amended prior to April 30, 1998, unless that engine’s foreign object ingestion service history has resulted in an unsafe condition; or (iv) Be shown to have a foreign object ingestion service history in similar installation locations which has not resulted in any unsafe condition. (b) Engine isolation. The powerplants must be arranged and isolated from each other to allow operation, in at least one configuration, so that the failure or malfunction of any engine, or of any systems that can affect the engine, will not: 1. Prevent the continued safe operation of the remaining engines; or 2. Require immediate action by any crewmember for continued safe operation. (c) Control of engine installations. There must be means for stopping the rotation of any engine individually in flight, except that, for turbine engine installations, the means for stopping the rotation of any engine need be provided only where continued rotation could jeopardize the safety of the airplane. Each component of the stopping systems on the engine side of the firewall that might be exposed to fire must be at least fire-resistant.  129 If hydraulic propeller feathering systems are used for this purpose, the feathering lines must be at least fire resistant under the operating conditions that may be expected to exist during feathering. (d) Turbine engine installations. For turbine engine installations: 1. Design precautions must be taken to minimize the hazards to the airplane in the event of an engine rotor failure or of a fire originating within the engine which burns through the engine case. 2. The powerplant systems associated with the engine control devices, systems, and instrumentation, must be designed to give reasonable assurance that those engine operating limitations that adversely affect turbine rotor structural integrity will not exceeded in service. (e) Restart capability 1. Means to restart any engine in flight must be provided. 2. An altitude and airspeed envelope must be established for in-flight engine restarting, and each engine must have a restart capability within that envelope. 3. For turbine engine powered airplanes, if the minimum windmilling speed of the engines, following when in-flight shutdown of all engines, is insufficient to provide the necessary electrical power for engine ignition, a power source independent of the engine-driven electrical power generating system must be provided to permit in-flight engine ignition for restarting. (f) Auxiliary Power Unit. Each auxiliary power unit must be approved or meet the requirements of the category for its intended use. 25.954 Fuel system lightning protection [5] The fuel system must be designed and arranged to prevent ignition of fuel vapor within the system by: (a) Direct lightning strikes to areas having a high probability of stroke attachment; (b) Swept lightning strokes to areas where swept strokes are highly probable; and (c) Corona and streamering at fuel vent outlets E.2 RTCA DO-160 RTCA DO-160 is a standard for environmental test of avionics hardware. DO-160 (see Appendix H), Environmental conditions and Test Procedures for Airborne equipment was published by RTCA (Radio Technical Commission for Aeronautics).  130 The DO-160 standard was first published on January 25, 1980 to specify test conditions for the design of avionics electronic hardware in airborne systems. Since then the standard has undergone subsequent revisions up through revision F [6]. This document outlines a set of minimal standard environmental test conditions (categories) and corresponding test procedures for airborne equipment. The purpose of these tests is to provide a controlled (laboratory) means of assuring the performance characteristics of airborne equipment in environmental conditions similar of those which may be encountered in airborne operation of the equipment [6]. The Standard includes sections on: ‐ Temperature ‐ Altitude ‐ Humidity ‐ Shock and Crash Safety ‐ Vibration ‐ Explosion proof ‐ Water proof ‐ Fluids susceptibility ‐ Sand and Dust ‐ Fungus Resist ‐ Salt and Fog ‐ Magnetic effect ‐ Power input ‐ Voltage Spike ‐ Audio frequency conducted susceptibility ‐ Induced signal susceptibility ‐ RF (radio frequency) emission and susceptibility ‐ Lightning susceptibility ‐ Icing ‐ ESD (electrostatic discharge) ‐ Flammability Sections 22 and 23 are related to lightning: ‐ Section 22: Lightning induced transient susceptibility ‐ Section 23: Lightning direct effects. [7] Revision E and F are driven by the use of composite materials used for airframe construction. Many composites do not conduct lightning currents the way metal airframes do; hence, the possibility of higher voltages and currents getting into cables and equipment of the aircraft. [8]  131 E.3 European Organisation for Civil Aviation Equipment (EUROCAE) The applicable standards of EUROCAE are [9]: • ED-84 (1997): Aircraft Lightning Environment and related Test Waveforms. Report of EUROCAE WG-31 and SAE Committee AE4L. • ED-81 (1996) Lightning Environment • ED-91 (1998)Aircraft Lightning Zoning Standard • ED-113 (2002) Aircraft Lightning Direct Effects Certification Group 31 in EUROCAE [9] WG-31 - Lightning The primary task of Working Group 31 is to prepare, in conjunction with other committees, documents concerning the effects of Lightning on aircraft and equipment. During the Year 2005-2006, WG-31’s activities included work on the following documents: • ED-105 "Aircraft lightning testing standard", which has been published • Continuing revision of DO-160 sect 22 for improvements to be included in DO-160 rev F • Completely revisited section 23, which will be submitted to WG-14 for inclusion in the next • ED-14 change to issue F • Work in conjunction with AE2 on Fuel couplers for AS5830 Future activities Possibilities for the development of new documents are being considered; these could include a restart of work on ED-81, AC 25.899-1 [9]. E.4 US Department of Transportation, Federal Aviation Authority (FAA) Advisory Circular 20-136 (1990): Protection of Aircraft Electrical/Electronic Systems against the indirect effects of lightning [10].  132 E.5 International Standards Organisation (ISO) ISO 7137 (2001): Aircraft - Environmental conditions and test procedures for airborne equipment [11]. E.6 Equivalences in FAA and EUROCAE During the early draft development of AC 20-155, the Federal Aviation Administration (FAA) had intended to recognize the fact that EUROCAE document ED-84, Aircraft Lightning Environment and Related Test Waveforms, was technically equivalent to SAE Aerospace Recommended Practice (ARP) document 5412 (same title), and that EUROCAE document ED-91, Aircraft Lightning Zoning, was technically equivalent to SAE ARP document 5414 (same title). However, prior to the release of AC 20-155, it was recognized that SAE ARP 5412 and ARP 5414 had both been revised to ARP 5412A and 5414A, respectively, whereas the same revisions had not been incorporated into the corresponding EUROCAE documents. Because of this, the EUROCAE documents were no longer considered “technically” equivalent, and their references were subsequently removed from the initial release of AC 20-155. EUROCAE has since updated documents ED-84 and ED-91, through amendment changes. The SAE AE-2 Lightning Committee has reviewed these amendment changes to EUROCAE documents ED-84 and ED-91 in light of the revisions that were made to SAE ARP 5412A and ARP 5414A. The SAE AE2 committee has concluded that: • EUROCAE ED-84, Aircraft Lightning Environment and Related Test Waveforms, when accompanied by Amendments 1, 2, and 3, is technically equivalent to SAE ARP 5412A, Aircraft Lightning Environment and Related Test Waveforms. • EUROCAE ED-91, Aircraft Lightning Zoning, when accompanied by Amendments 1 and 2, is technically equivalent to SAE ARP 5414A, Aircraft Lightning Zoning. This review was documented in an SAE AE-2 Lightning Committee Correspondence to the FAA dated June 8, 2007. The FAA concurs with this position, and agrees that the EUROCAE documents, with the applicable Amendments, are interchangeable with their corresponding SAE ARP. [12]  133 E.7 Standard comparison All the standards are not the same. It depends on the manufacturer, but they have to be in accordance with the regulating law (see Table E.7.1 ). [13] Table E.7.1 Standard Comparison [13] E.8 References [1] Lightning and Surge, G&M Compliance, Inc. [Electronically accessed 12 March 2010], <http://gmcompliance.thomasnet.com/item/all-categories/lightning-surge-2/item- 1007?&forward=1> [2] The American Association for Laboratory Accreditation, A2LA, The American Association for Laboratory Accreditation, [Electronically accessed 11 March 2010], <http://www.a2la.org/scopepdf/1719-02.pdf> [3] Lightning Effects on Aircraft of the composite material, Metallum, [Electronically accessed 12 March 2010], <http://www.metallum.com.br/17cbecimat/resumos/17cbecimat-205-004.pdf> [4] Lightning Protection of Aircraft, IEEE, [Electronically accessed 15 Marchg 2010], <http://eeeic.eu/proc/papers/84.pdf> [5] Federal Aviation Regulations, Flight Sim Aviation, [Electronically accessed 16 March 2010], <http://www.flightsimaviation.com/data/FARS/part_25.html>  134 [6] DO-160, Wikipedia, the free encyclopedia, Updated 23/03/2010, [Electronically accessed 23 March 2010], <http://en.wikipedia.org/wiki/DO-160> [7] DOD-160, CELAB, your solution in certification, [Electronically accessed 3 April 2010], <http://www.ceinfo.eu/DOD160.htm> [8] Updates on RTCA DO-160, IEEE, [Electronically accessed 02 March 2010], <http://www.google.es/url?sa=t&source=web&ct=res&cd=1&ved=0CAYQFjAA&url=http%3A%2 F%2Fewh.ieee.org%2Fr6%2Focs%2Femc%2Fimages%2Fpdf%2Fupdates%2520on%2520rtca %2520do- 160%2520lightning%2520testing%25202.ppt&rct=j&q=and+F+are+driven+by+the+use+of+com posite+materials+used+for+airframe+construction.+Many+composites+do+not+conduct+lightnin g+currents+the+way+metal+airframes+do%3B+hence%2C+the+possibility+of+higher+voltages +and+currents+getting+into+cables+and+equipment+of+the+aircraft.&ei=rBvHS5_uA5P9_AaN u4TYDA&usg=AFQjCNGLAVrocNjamt67J1Aby9WBec9B3Q> [9] EUROCAE Annual Report (2005-2006), EUROCAE, [Electronically accessed 03 March 2010], <http://www.eurocae.net/annualreport.pdf> [10] Avionics Test System, EMC Partner, [Electronically accessed 12 March 2010], <http://www.emc-partner.com/resource/pdf/e-aircraft.pdf> [11] Lightning Testing, Trac Global, [Electronically accessed 23 March 2010], <http://www.tracglobal.com/lightning-testing.html> [12] Updates to Advisory Circular (AC) 20-155, SAE Documents to Support Aircraft Lightning Protection Certification, Updated 4/28/2006, [Electronically accessed 23 March 2010], <http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2020- 155/$FILE/AC%2020-155_update.pdf> [13] Explanation and Experiences with RTCA/DO160 Level 5 avionics testing, EMC Partner, [Electronically accessed 24 March 2010], < http://www.emc-partner.com/resource/pdf/a_do- 160_level5.pdf>   APPENDIX F. FAA REGULATIONS   135 FAA Federal Aviation regulations (FARS, 14 CFR) Part 33 Section 5. Instruction manual for installing and operating the engine. [1] Each applicant must prepare and make available to the Administrator prior to the issuance of the type certificate and to the owner at the time of delivery of the engine, approved instructions for installing and operating the engine. The instructions must include at least the following: (a) Installation instructions 1. The location of engine mounting attachments, the method of attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and related structure. 2. The location and description of engine connections to be attached to accessories, pipes, wires, cables, ducts, and cowling. 3. An outline drawing of the engine including overall dimensions. (b) Operating instructions: 1. The operating limitations established by the Administrator. 2. The power or thrust ratings and procedures for correcting for nonstandard atmosphere. 3. The recommended procedure, under normal and extreme ambient conditions for: (i) Starting; (ii) Operating on the ground; and (iii) Operating during flight. F.1 Reference [1] Regulations, Flight Sim Regulations, [Electronically accessed 15 April 2010], <http://www.flightsimaviation.com/data/FARS/part_33-5.html>        136 APPENDIX G. TESTS G.1 Carbon Fibre Measures of the material: 232 x 26.18 x 2.24 mm 1. Values V = 24 V R = 3.3 Ω The value of the resistance is very small. The carbon fibre conducts electricity a little bit, so with R = 3.3 Ω it is a short circuit. 2. Values V =24 V R = 220 Ω ρ = 10-9 Ω·m The current in the circuit (see Figure G.1.1) should be (theoretically): I = 0.109 A The results obtained (see Table G.1.1): Table G.1.1 Carbon Fibre Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 0.639 0.612 0.611 0.599 0.589 0.591 0.592 0.567 0.589 0.584 I (A) 0.2 0.2 0.2 0.1 0.1 0.2 0.1 0.2 0.2 0.2 VR (V) 23 23 23 23 23 23 23 23 23 23  137 Figure G.1.1 Carbon Fibre Test Note: The temperature in the resistance increases. The amperimeter fluctuates, when the current is a little bit over 0.1 it changes into 0.2. G.2 Galvanized carbon steel Values Measures of the material: 91.21x19.12x0.97 mm V =24 V R = 220 Ω The current in the circuit (see Figure G.2.1) should be (theoretically): I = 0.109 A The results obtained (see Table G.2.1):  144 Figure G.7.1 Copper Test G.8 Glass fibre 1 Values Measures of the material: 64.13x10.36x0.31mm V =24 V R = 120 Ω The current in the circuit (see Figures G.8.1 and G.8.2) should be (theoretically): I = 0.2 A The results obtained (see Table G.8.1): Table G.8.1 Glass Fibre 1 Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A 0 0 0 0 0 0 0 0 0 0 VR (V 0 0 0 0 0 0 0 0 0 0  145 Figure G.8.1 Glass Fibre 1 Test (VM) Figure G.8.2 Glass Fibre 1 Test (VR) G.9 Wood Values Measures of the material: 118.48x35.90x11.95mm V =24 V R = 120 The current in the circuit (see Figures G.9.1 and G.9.2) should be (theoretically): I = 0.2 A  146 The results obtained (see Table G.9.1): Table G.9.1 Wood Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V) 0 0 0 0 0 0 0 0 0 0 Figure G.9.1 Wood Test (VM) Figure G.9.2 Wood Test (VR)  147 G.10 Polyethylene Values Measures of the material: 109.46x28.66x12.34mm V =24 V R = 120 The current in the circuit (see Figures G.10.1 and G.10.2) should be (theoretically): I = 0.2 A The results obtained (see Table G.10.1): Table G.10.1 Polyethylene Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V 0 0 0 0 0 0 0 0 0 0 Figure G.10.1 Polyethylene Test (VM)  148 Figure G.10.2 Polyethylene Test (VR) G.11 Foam Values Measures of the material: 45.26x45.08x9.43mm V =24 V R = 120 The current in the circuit (see Figures G.11.1 and G.11.2) should be (theoretically): I = 0.2 A The results obtained (see Table G.11.1): Table G.11.1 Foam Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V) 0 0 0 0 0 0 0 0 0 0  149 Figure G.11.1 Foam Test (VM) Figure G.11.2 Foam Test (VR) G.12 Epoxy resin Values Measures of the material: 55.71x22.43x1.46mm V =24 V R = 120 The current in the circuit (see Figures G.12.1 and G.12.2) should be (theoretically): I = 0.2 A The results obtained (see Table G.12.1):  150 Table G.12.1 Epoxy resin Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V) 0 0 0 0 0 0 0 0 0 0 Figure G.12.1 Epoxy resin Test (VM) Figure G.12.2 Epoxy resin Test (VR)  151 G.13 Semi-conducting self-fusing tape Values Measures of the material: 119.67x18.90x0.8mm V =24 V R = 220 The current in the circuit (see Figure G.13.1) should be (theoretically): I = 0.109 A The results obtained (see Table G.13.1): Table 7.2.13.1 Semi-conducting self-fusing tape Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 21 21 21 21 21 21 21 21 21 21 I (A) 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 VR (V) 2.98 3.03 3.03 3.04 3.04 3.05 3.04 3.04 3.04 3.05 Figure G.13.1 Semi-conducting self-fusing tape Test  152 G.14 Glass fibre 2 Values Measures of the material: 60x18.57x0.01mm V =24 V R = 120 The current in the circuit (see Figures G.14.1 and G.14.2) should be (theoretically): I = 0.2 A The results obtained (see Table G.14.1): Table G.14.1 Glass Fibre 2 Test Results Figure G.14.1 Glass Fibre 2 Test (VM) 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V) 0 0 0 0 0 0 0 0 0 0  153 Figure G.14.2 Glass Fibre 2 Test (VR) G.15 Plastic Values Measures of the material: L=82.02mm Ø=25.26mm V =24 V R = 220 The current in the circuit (see Figures G.15.1 and G.15.2) should be (theoretically): I = 0.109 A The results obtained (see Table G.15.1): Table G.15.1 Plastic Test Results 1 2 3 4 5 6 7 8 9 10 VM (V) 24 24 24 24 24 24 24 24 24 24 I (A) 0 0 0 0 0 0 0 0 0 0 VR (V) 0 0 0 0 0 0 0 0 0 0