1. Chronology Technical Overview SAE Guidance Documents Requirements History of System Lightning Requirements- Highlights

2. SAE – In Response to a Military Request for Assistance, SAE Forms Special Task F-Approximately Four Decades Ago – Special Task F Becomes AE4L-Approximately Three Decades Ago – AE4L Becomes AE2-1999 Military – MIL-STD-1757- Approximately Three Decades Ago – MIL-STD-1795- Approximately Three Decades Ago – MIL-STD 461 Upgrade-1993 – MIL-STD-464 - 1997 FAA – Original Regulation-Approximately Three Decades Ago – Original AC 20-136-Between Two to Three Decades Ago Chronology

3. Special Task F Determine Lightning Environment from Measurements During Strikes to Towers Followed the Space Shuttle lightning criteria committee and NASA 07636 Developed MIL-STD-1757 Developed MIL-STD-1795 Published Red and Blue Book Committee Reports

4. Establish Charter – Scope  It is the Duty of the Committee to Produce Advisory Materials for the Aerospace Community in the Following Areas:  The Natural Lightning Environment and Related Atmospheric Electrical Standards  Protection of Aerospace Vehicles from the Effects of Lightning and Other Atmospheric Electrical Environments  Means of Verifying the Adequacy of Protection Measures  Standardized Simulation and Test Methods for Lightning and Other Atmospheric Electrical Environments – Objectives  Provide a Forum for the Exchange of Technical Information Relating to the Above Technology Areas  Share and Coordinate the Development of Technical Material with the Comparable International Communities along with Harmonizing the U.S. and International Forums within the Committee’s Scope AE2/AE4L

5. – Objectives (Continued)  Compile and Review Information on Naturally Occurring Lightning and Other Atmospheric Electrical Environments  Characterize and Define Engineering Standards Based on Naturally Occurring Lightning and Other Atmospheric Electrical Environments  Develop Simulation and Test Procedures for Use in Evaluating Lightning and other Electrical Effects on Aerospace and Systems  Identify Areas where Knowledge is Lacking and Recommend Research to Fill in Knowledge Gaps  Provide a Forum for the Exchange of Technical Information Relating to the Above Technology Areas  Share and Coordinate the Development of Technical Material with the Comparable International Communities along with Harmonizing the U.S. and International Forums within the Committee’s Scope AE2/AE4L (Continued)

6. Determine (Multiple Burst Environment from In-Flight Measurements During Lightning Strikes to the F-106)-Between Two and Three Decades Ago Publish Guidance Documents AE2/AE4L (Continued)

7. Lightning Environment Characterization for System Requirements-Between Three to Four Decades Ago Relationship Between Waveforms 1,2 and 3- Approximately Four 4 Decades Ago Waveform Derivation-Between Three to Four Decades Ago Voltage/Current Levels-Between Three to Four Decades Ago Indirect Effects Technical - Overview

8. Lightning Environment Characterization for System Requirements External – Data from Measurements of Lightning Strikes to Towers-Approximately Four Decades Ago  Current Components A and D  Multiple Stroke – In-Flight Measurements During Lightning Strikes to an Airplane- Approximately Three Decades Ago  Current Component H  Multiple Burst Internal – Internal Magnetic Fields Due to Aperture Coupling of Current Components A,D and H External Magnetic Fields – Waveforms 1,2 and 3 Voltages and Currents also Waveform 6 Current- Coupling of the Current Components A and H Internal Magnetic Fields (Forcing Function) to Aircraft Wiring

9. Internal (Continued) – Waveform 3 H Voltages and Currents also Waveform 6 Current- Coupling of the Current Component H Internal Magnetic Fields to Aircraft Wiring – Waveforms 4 and 5 Voltages and Currents-Resistive Drop Across an Aerospace Vehicle Structure Due to Current Component A Lightning Environment Characterization for System Requirements (Continued)

10. Relationship Between Waveforms 1,2 and 3 Analytic Derivation from B-1 NEMP Threat – Maxwell Partial Differential Equations For an Electromagnetically Simple Configuration (a Scatter where the Diameter < < than the Length) Reduces to a Linear Differential Equation – When the Forcing Function is the Current Component A Magnetic Field, the Differential Equation Solution Yields:  Criteria for an Electrically Long or Short Configuration  Criteria for an Electrically Long Configuration-Solution Contains Waveform 3 Only  Electrically Short Configuration-Solution Contains a Combination of Waveform 2 and Waveform 3  Electrically Long Configuration-Solution Contains Waveform 3 Only

11. Also Derived: – Two as the Ratio of Voltage Waveform 3 to Voltage Waveform 2 (Solution from Linear Differential Equation Approximation of Maxwell’s Equations- Ratio Emphasizes Waveform 2 Voltage) – Five as the Ratio of Waveform 2 Voltage to Waveform 1 Current  The Absolute Value of Waveform 2 Voltage is Equal to Inductance Times the Absolute Value of the Derivative of Waveform 1 Current (Faraday’s Equation from Faraday’s Law)  Inductance is in the 1 to 2 Micro-Henry Range –Realistic Estimate for The Inductance Minimum Value Resulted in the Minimum Waveform 2 Voltage to Waveform 1 Current Ratio of Five –Value for Inductance was a Result of a Realistic Estimate of Minimum Wire Length  Equation Used for Current Component A Peaked at Two Micro-Seconds  Equation of Waveform 1 Current the Same Form as the Equation for Current Component A – Twenty Five (Conservative Value of Traveling Wave Characteristic Impedance) as the Ratio of Waveform 3 Voltage to Waveform 3 Current Relationship Between Waveforms 1,2 and 3 (Continued)

12. Waveform 1-Drived From Analysis and Pulse Testing Between Three and Four Decades Ago Waveform 2-Drived From Analysis and Pulse Testing Between Three and Four Decades Ago Waveform 3-Drived From Analysis and Pulse Testing Between Three and Four Decades Ago Waveform 3 Frequencies (1MHz and 10MHz) Accommodates Range of Aircraft Geometries Waveform 4-Drived From Analysis and Pulse Testing Between Three and Four Decades Ago Waveform 5-From Pulse Testing Approximately Three Decades Ago Waveforms 3H and 6-From Pulse Testing Approximately Three Decades Ago Waveform Derivation-Between Three and Four Decades Ago

13. Voltage/Current Levels For a Single Wire, Empiric (Pulse Testing) Measurements Verify: – Two as the Ratio of Waveform 3 Voltage to Waveform 2 Voltage-Value that was Analytically Derived – Five as the Ratio of Waveform 2 Voltage to Waveform 1 Current-Value that was Analytically Derived – Twenty Five as the Ratio of Waveform 3 Voltage to Waveform 3 Current- Conservative Value for the Traveling Wave Characteristic Impedance Waveform 2 and Waveform 3 in the Solution for the Electrically Short Configuration Decomposed into Individual Waveforms (Waveform 2 Voltage Component and Waveform 3 Voltage Component) Current Component A-For Cables, Ratios Based on Pulse Testing Measurements – One Half as the Ratio of Waveform 2 Voltage to Waveform 1 Current – Five as the Ratio of Waveform 3 Voltage to Waveform 3 Current – One Half as the Ratio of Waveform 4 Voltage to Waveform 1 Current – One Third as the Ratio of Waveform 5 Current to Waveform 4 Voltage

14. Current Component H-Ratio For Cables, Based on Pulse Testing Measurements – Sixty as the Ratio of Waveform 3H Voltage to Waveform 3H Current-Value of Traveling Wave Characteristic Impedance also – For Current Component H Magnetic Field All Circuits of Practical Length Will be Electrically Long and Waveform 3H will be the Only Response – Waveform 6 Current Only (Circuits that Are Completely Shielded) Provides Design Criteria that is Independent of Aerospace Vehicle Type and Installation Practices Systems Integrator Tool that Enables: – A System Integrator to Specify Interface Circuit Voltages and Currents- Resulting from the Control of Internal Magnetic Fields by Installation Design Practices – A System Integrator to Select Electrical/Electronic Equipment-Qualified to the Unique Voltage/Current Requirements Resulting From his Installation Voltage/Current Levels (Continued)

15. Systems Integrator Tool that Enables(Continued): – A System Integrator to Select Electrical/Electronic Equipment that has been Qualified to Industry Standards Resulting in Equipment that is Compatible with His Installation Requirements – Installation Design (shielding, etc) Controls the Magnitude of Internal Magnetic Fields and the Resulting Voltages and Currents Induced by those Fields) Equipment Manufacturer Tool that Enables: – Choice of a Level from an Industry Standard to Qualify Equipment to Customer Requirements – Choice of a Level from an Industry Standard to Qualify Equipment Based on Market Demands Voltage/Current Levels (Continued)

16. Indirect Effects Electronic Component Damage (Hard Fault-Digital Circuit)- Waveforms 1,2,3(1MHz),4,5,6 (Possibly)and Multiple Stroke – Non-Recoverable Circuit – One or More Component Replacement Electronic Circuit Upset (Soft Fault-Digital Circuit): Waveforms 1,2,3, (1MHz and10MHz),4 6, Multiple Stroke and Multiple Burst – Circuit Recoverable – System/Equipment Recoverable

17. Red Book Committee Report (Superseded by Blue Book) Blue Book Committee Report, “Lightning Test Waveforms and Techniques for Aerospace Vehicles and Hardware”- 1978 Yellow Book Committee Report AE4L-81-2, “Test Waveforms and Techniques for Assessing the Effects of Lightning-Induced Transients” Original Orange Book Committee Report AE4L-87-3, “Protection of Aircraft Electrical/Electronic Systems Against the Indirect Effects of Lightning“Guidance-SAE SAE Guidance Documents

18. Committee Report AE4L-87-3 Rev C, “Certification of Aircraft Electrical/Electronic Systems Against the Indirect Effects of Lightning“ Purple Book Committee Report AE4L-97-4, “Aircraft Lightning Environment and Related Test Waveforms Standard“ ARP 5412, “Aircraft Lightning Environment and Related Test Waveforms ”-Between One to Three Decades Ago ARP 5413, “Certification of Aircraft Electrical/Electronic Systems for the Indirect Effects of Lightning” (Provided the Technical Basis for AC 20-136B and was Superseded by AC 20-136B)- Between One to Three Decades Ago SAE Guidance Documents (Continued)

19. ARP 5415, “User’s Manual for Certification of Aircraft Electrical/Electronic Systems for the Indirect Effects of Lightning”-2001 ARP 5416, “Aircraft Lightning Test Methods”-Proposed Draft 2005 Technical Basis – The Technical Content within the Blue, Yellow and Orange Books Provided the Technical Basis for the Purple Book, ARPs 5412, 5413, 5415 and MIL-STD-464 – Airframe and Equipment Suppliers Testing Experience Provided the Technical Basis for ARP 5416 SAE Guidance Documents (Continued)

20. Defined Lightning Environment from which that Portion Relevant to System Requirements Can be Extracted Lightning Environment Relevant to System Requirements-Indirect Effects on Electronic Systems – Current Components A and D – Multiple Stroke-Current Component A Followed by a Half Value Current Component D Group of Twenty Three Blue Book Committee Report

21. Committee Report AE4L-81-2 System Test – Triple Plate – Cable Injection Equipment Test – Cable Injection for Upset/Damage Tolerance-Pseudo System Test – Circuit Interface Injection for Upset and Damage Tolerance-Pseudo Pin Test – Direct Circuit Injection for Damage Tolerance-Pin Test Defined Lightning Multiple Burst Environment – Current Component H – Multiple Burst-Twenty Four Bursts where each Burst is Composed of Twenty Current Component H Pulses Introduction of Waveform 4 Voltage and Current for Upset Direct Circuit Injection (Damage Tolerance)

22. Description of Waveforms 1,2,3 and 4 – Waveform 1 Peaks at Two Micro-Seconds – Waveform 1,2 and 4 Descriptions Eventually Re-adjusted Table of 5 Levels that give Voltage to Current Ratios for an Individual Interface Circuit – Each Level Provides a Description of Equipment Vulnerability that Implies an Equipment Qualification Requirement for Each Interface Circuit – Implies a Requirement for Installation Designers to Select a Level and then Control the Internal Environment to be Compatible with the Level that has been Selected – Levels Lower than Level 5 are separated by a factor of Approximately 2.5- Engineering Judgment Committee Report AE4L-81-2 (Continued)

23. Level Descriptions (Equipment Focus) – Level 5 Is an upper limit on transients to which subsystem equipment should be exposed. Transients which lightning could Induce in long and/or exposed wiring should be controlled to be consistent with this level. The power associated with this level represents a threat to most electronic interface circuits and the impact on equipment practices will be significant. Additionally, the open circuit voltage associated with is within region where the withstand capability of the insulation medium (air, fiberglass, teflon, etc.) at equipment connectors or between equipment circuit paths could be exceeded. – Level 4 Is representative of severe transients which may appear on power lines and is comparable to the power line transients defined in MIL-STD-704 (Waveform 2). It is also representative of the upper limits which have been defined for induced interface wiring transients that may be produced by a nuclear electromagnetic pulse (NEMP) and that form equipment survivability/vulnerability (SV) requirements (Waveform 3). The level is appropriate for equipment designed to include such requirements. Lightning induced transients should be controlled to be consistent with such NEMP S/V levels. The power associated with this is relatively severe and its impact on equipment design practices will probably be significant.

24. Level Description (Continued) – Level 3 Is Representative of the more intense transients which may be produced during normal operation. – Level 2 Is intended for equipment which will be installed in environments where lighting-induced transients would be controlled to a level which is consistent with that represented by MIL- STD-461/462 or similar standards, This level is considered to be consistent with good engineering for such equipment and should have a relatively minor impact on the associated design practices. – Level 1 Is intended for off-the-shelf noncritical equipment which will be installed in a controlled environment. It is the minimum level considered to be consistent with good engineering practice. Committee Report AE4L-81-2 (Continued)

25. Committee Report AE4L-87-3 (Orange Book) Approaches to Compliance Margins and Verification Methods – Margin Defined as the Difference Between TCL and ETDL  Transient Control Level (TCL)  Equipment Transient Design Level (EDTL) – Verification Methods  Test  Analysis  Test and Analysis Major Elements of Verification Compliance Maintenance and Surveillance

26. Description of: – Current Component A Adjusted-Peaks in 6.4 Micro-Seconds – Description of Current Component H-Peaks in Approximately 2 Nano- Seconds – Description of Multiple Stroke – Description of Multiple Burst Description of Waveforms 1,2 and 4 Adjusted-Because of Current Component A Magnetic Field, Waveforms 1 and 4 Peak at 6.4 Micro- Seconds 1 MHz and 10 MHz Waveform 3 Frequencies Account for the Range of Aircraft Dimensions (Engineering Judgment) Ratios of Voltage in Yellow Book Table of Levels, are Retained in Orange Book Levels Committee Report AE4L-87-3 (Continued)

27. Level Descriptions (Installation Focus) – Levels 4 and 5 Are for equipment and interconnect wiring that will installed in severe electromagnetic environments. Such levels might be found in all-composite aircraft, where special shielding practices have not been employed. – Level 3 Is typical for equipment and interconnect wiring that will be installed in a moderate environment such as the more electromagnetically open areas (eg, cockpit) of an aircraft composed principally of metal. – Level 2 Is typical for equipment and interconnect wiring that will be installed in a controlled environment such as an enclosed avionics bay of an all metal aircraft. – Level 1 Not Applicable. Committee Report AE4L-87-3 (Continued)

28. Environment Information and Test Waveforms Removed from AC 20 – 136 and AC 20 – 53 and Included in This Document Natural Lightning Description Lightning Interactions with Aircraft Idealized Standard Lightning Environment Idealized Standard Induced Transient Waveforms Committee Report AE4L-97-4

29. Natural Lightning Description Lightning Interaction with Aircraft Idealized Standard Lightning Environment Idealized Standard Induced Transient Waveforms Summary of Waveforms/Waveform Sets ARP 5412

30. Approaches to Compliance – Review Safety Assessment – Determine the Lightning Strike for the Aircraft – Establish the Exterior Lightning Environment for the Zone – Establish the Exterior Effects of the Internal Environment – Establish Transient Control Levels and Equipment Transient Design Level – Verify Compliance Effects of Induced Transients – Component Damage – System Functional Upset Margins and Verification Methods ARP 5415

31. Major Elements of Compliance – Level A Requirements – Level B and Level C Requirements – Example 1 – System Test Levels Developed from Low Current Pulse Test – Example 2 – System Test Levels Developed from Low Current Pulse Test – Example 3 – System Test Levels Developed from Swept Frequency Test Maintenance, Surveillance, Repair and Modification – Maintenance Procedures and Lightning Protection – Aircraft Modification and Lightning Protection – Protection Assurance Program – In-Service Maintenance Test Techniques ARP 5415 (Continued)

32. Planning of Lightning Effects Tests – Test Object Conformity – Test Procedure – Measurement Set-UP Calibration – Test Safety Aspects – Test Set-UP – Test Object Design – Waveform Scaling – Waveform Application – Concurrent Testing ARP 5416

33. Indirect Effects Test Methods – Aircraft Tests – Return Conductor Arrangement – Measurements Set-UP Calibration – Swept – Pulse Test – Tests for Equipment/Systems – Equipment Damage Tolerance Tests – Equipment Functional Upset Tests – System Functional Upset Tests – Wire Bundle Shield Transfer Function Test – Wire Bundle Shield Transfer Function Using Lightning Pulse Injection Method – Wire Bundle Shield Transfer Function Using Swept Frequency Test – Shield/Conductor Handling Test ARP 5416 (Continued)

34. Lightning System Functional Upset Testing SAE ARP5416 Section 6.3.4: Applies Multiple Stroke and Multiple Burst Environments to Systems Comprised of Multiple Boxes and Cables via Simultaneous Injection

35. Military FAA RTCA-DO160/Section 22 Requirements

36. MIL-STD-1757, “Lightning Qualification Techniques for Aerospace Vehicles and Hardware” (Environment Definition that Included Current Components A and D which are Relevant to System Requirements) MIL-STD-1795, “Lightning Protection of Aerospace Vehicles and Hardware” (see MIL-STD-1757) MIL-STD-461 (Upgraded to Include Equipment Tests for Lightning Effects) MIL-STD-464 (Lightning Environment Section Extracted from MIL- STD-1757 and ARP 5412) Military

37. Regulation AC 20-136 FAA

38. Regulation-Present CFRs 23.1306, 25.1316, 27.1316, 29.1316 (a) Each electrical and electronic system that performs a function, for which failure would prevent the continued safe flight and landing of the airplane, must be designed and installed so that- 1.The function is not adversely affected during and after the time the airplane the airplane is exposed to lightning and 2.The system automatically recovers normal operation of that function in a timely after the airplane is exposed to lightning. (b) Each electrical and electronic system that performs a function, for which failure would reduce the capability of the airplane or the ability of the flightcrew to respond to an adverse operating condition, must be designed and installed so that the function recovers normal operation in a timely manner after the airplane is exposed to lightning.

39. A Means but not the Only Means to Show Compliance With 23.1306, 25.1309, 27.1309 and 29.1309 Steps for showing Compliance – Identify the systems to be assessed – Determine the lightning strike zones for the aircraft – Establish the aircraft lightning environment for each zone – Determine the lightning transient environment associated with the system – Establish Equipment Design Transient Levels (EDTLs also see Orange Book) and Aircraft Actual Transient Levels (ATLs): the Difference Between EDTL and ATL is the Margin – Verify compliance to the requirements – Take corrective measures if needed Effects of Transients – Component Damage – System Functional Upset AC 20-136 “Aircraft Electrical and Electronic System Lightning Protection”

40. Level A System Lightning Certification – Identify Level A Systems – Establish System EDTLs – Determine ATLs Using Aircraft Testing – Determine ATLs Using Analysis – Determine ATLs Using Similarity – Determine Transient Levels Using DO160/Section 22 Guidance for Level A Displays Only – Verify System EDTLs Using System Qualification Tests – Verify System EDTLs Using Existing System Data (Similarity) – Verify Compliance to the Requirements – Take Corrective Measures AC 20-136 (Continued)

41. Level B and C System Lightning Certification – Identify Level B and C Systems – Establish EDTLs – Verify System EDTLs Using Equipment Qualification Tests – Verify System EDTLs Using Existing Equipment Data (Similarity) – Take Corrective Measures – Maintenance and Surveillance AC 20-136 Environment Information Removed AC 20-136 (Continued)

42. Level A-Each Electrical and Electronic System that Performs a Function, for which a Failure would Prevent the Continued Safe Flight and Landing of the Aircraft Level B and C-Each Electrical and Electronic System that Performs a Function, for which a Failure would Reduce the Capability of the Aircraft or the Ability of the Flightcrew to Respond to an Adverse Operating Condition System Classification Levels

43. Original- Developed in Conjunction with AE4L-87-3 DO160/Section 22 Revision G – Definition of Categories – Tables of Levels (Requirement) for:  Cable Induction  Ground Injection  Direct Interface Injection (Pin) – Voltage to Current Ratios are Based Upon Ground Tests for:  Cable Induction  Ground Injection – Specification of Test Setup and Procedures for:  Cable Induction  Ground Injection  Direct Interface Injection RTCA/DO160 Section 22

44. DO160/Section 22 Revision G (Continued) – Waveform 5  Description  Current to Voltage ratio Based on Ground Tests – Multiple Stroke – Multiple Burst RTCA/DO160 Section 22 (Continued)

45. Equipment Lightning Indirect Effects Testing DO160 Section 22: To Assess Damage and Upset-Applies Lightning Indirect Effects Transients (Voltages and Currents) to Equipment Interfaces via Cable Injection, Ground Injection and Direct Injection