Aircraft Electromagnetic Compatibility
R78977DOT/FAA/CT-86/40Aircraft Electromagnetic Compatibility us 7-23856(USA-CR-181051)AIRCBA?T BL C!TEOIAGIBIICCCIPATXBILITX Pima1 Baport, Sep. 1985June19437 ( B o e h g Ccrmrcial Airplane Co-) 146F Avail: O f l S EC 407/IJP A01CSCL 20n-UaclasG3/320078857Clifton A. ClarkeBoeing Commercial Airplane CompanySeattle, WA 98124William E. LarsenFAA Technical Field OfficeMoffett Field, CA 94035Final ReportJune 1987This document is available to the U.S. public through the National Technical InformationService, Springfield, VA 22161U.S. Department of TransportationFederal Aviation AdministrationFAA Technical CenterAtlantic City, NJ 08405
Aircraft Electromagnetic CompatibilityClifton A. ClarkeBoeing Commercial Airplane CompanySeattle, WA 98124William E. LarsenFAA Technical Field OfficeMoffett Field, CA 94035.a
FOREWORDThis document is based on work performed by the Boeing Commercial Airplane Company,P.O.Box 3707, Seattle, Washington 98124, under NASA contract NAS2-12261 for the Federal Aviation Administration, NASNAmes Research Center, Moffett Field, CA 94035. Thecontract was firm fmed price, level-of-effort term from September 1985 to September 1986with an extension to June 1987. Contracting officers were W. C. Botts, Boeing and A. N.Johnson, NASA. The FAA contracting officer’s technical representative was William E. Larsen. Deliverables were an Interim Report (Draft) and an Interim Report (Final). The program manager was Robert D. Force, and principal investigator, Clifton A. Clarke.Bob Force, who helped put the program together, played a central part in managing theplanning and organization of the total document. The Section 2.1, “Existing Systems,” isderived from the valuable “Active Controls Technology” report which Bob co-authored. BillLarsen provided extensive expertise taken from his own experience, and through constructive source material. He also provided sound and highly regarded recommendations for content and organization. Dale R. Reed collaborated on the wiringinduced voltages and workedsome of the indepth computations. He offered very profitable perspectives on the approach toaircraft engineering analysis and design; his forbearance and tenacity are appreciated.Special contributions were made by John “inner and John Bishop who consulted on significant aircraft test and troubleshooting procedures, helping to fill in the picture of aircraftelectromagnetic interference. Veteran EMC engineers who supplied valued and time-testeddata that form a part of this report were Jerry Carter, John Foster, and George Ketterling.Thanks are also due those individuals mentioned or quoted in the text.Many people contributed important comments and helpful criticisms to the Interim Report(Draft). Chris Kendall supplied valuable consultations and comments along with Roger McConnell of CKC Associates. Henrietta Gilbert, FAA; Richard Hess, Sperry Corp.; RussellCarstensen, Naval Air Systems Command; and Kary Miller of Collins generously took timeto review and comment with useful corrections and suggestions. My thanks are also owed toNancy Clarke for helpful editorial comments. Fellow EMC engineers Glenn Olson, KiethKalanquin, Charles King, and Sy O’Young (who worked on the proposal) contributed theirthoughts.The document format and graphics were expertly delineated by Primo Mattieligh and drawnby Irene Ohashi. Their generosity and patience are much appreciated. Gary Breidensteinoffered expert aid in the editing, and was a source of inspiration in the preparation of thefinal copy. Nancy Eaton not only supervised the typing, but helped proof the manuscript.This document would not be possible without the unparalleled IEEE Symposium Recordsand the periodical “ITEM’, R & B Enterprises, whose presentations were a source of valuable data applicable to an aircraft. I am collectively indebted.i
TABLE OF CONTENTSPAGE1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11127710102.0 AIRPLANE AVIONICS AND CRITICALITIES .2.1 Existing Systems .2.2 Future Aircraft .2.3 Criticalities .2.3.1 Measures and Definitions .2.3.2 Critical Equipment .2.4 Packaging and Architecture .2.5 Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5.1 An Early Start .2.5.2 Design .2.5.3 Environment and Test .2.6 Variances in Electromagnetic Compatibility .2.6.1 Diagnostics and Troubleshooting .2.6.2 %able of Variances .2.6.3 Corrective Action and Modeling .131328373738403.0 AVIONICS THRESHOLDS AND PROTECTION .3.1 Hardware Tolerance .3.2 EM1 and Software .3.3 Digital and Discrete Circuits .3.3.1 ARINC 429 Drivers and Receivers .3.3.2 Circuit and Shield Grounds .3.3.3 Discretes .3.4 Equipmentmiring Isolation and Separation .3.4.1 Quality of Wiring Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.4.2 Power and Energy Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.4.3 EMC Quality in Maintenance .3.4.4 Shielding and Shield Ties.3.5 Aircraft Protection Measures .3.5.1 Structure Conductivity .3.5.2 Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.5.3 Safety in Grounding and Returns .3.5.4 Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.5.5 Resonance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.6 Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .535355575758606060646768686871777882821.1 Background and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.1.1 A Case of Engine Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.1.2 Electromagnetic Compatibility .1.2 Electromagnetic Compatibility Priorities .1.2.1 Responsibilities and Policies .1.2.2 Documentation .1.3 How to Use This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ii4343444446464848
4.0 EMC ANALYSIS AND ENVIRONMENT .4.1 Radiated Environment .4.1.1 Radio Frequency Field Distribution .4.1.2 Magnetic and Electric Field Distribution .4.1.3 Transients .4.2 Aircraft Protection .4.2.1 Shielding and Ground Reference .4.2.2 Apertures and Electrical Bonding .4.2.3 External Wiring Interface Circuits .4.2.4 Circuit Protection .4.3 Trades .878787939697979999100101. 5.0 ACTIVITIES AND DOCUMENTS .5.1 SpecificationsDocuments .5.2 TasksIActivities .1071071086.0 EQUIPMENT SPECIFICATION .6.1 New and Existing .6.2 Aircraft Equipment Categories .6.3 Suppliers .1111111121147.0 VERIFICATION AND VALIDATION .7.1 Key EMC Designs .7.2 Validation Plans .7.3 Validation Procedure .7.4 Program Design Reviews .1171171171181208.0 BIBLIOGRAPHY .123APPENDIX A Glossary of Terms .131APPENDIX B Test and Test Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
.LIST OF stulated Percentages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Representative EM1 Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .EM1 Environment in Aircraft .Percent Troubleshooting-NC .Electromagnetic Interference Effects .Radio Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cost-Effective Subsystem Testing .Key EMC Facilitators .Representative “E” Field Coupling .Present-Day Aircraft Systems .Avionics Bays .Wiring .Main Bay Aluminum Structure .Structure Return .InducedNoise .Noise Voltages .Nonmetallic Interfaces .1. .Separation Example .2.1-10Flight Control Autopilot Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1-13.1-2Electronic Engine Control .TransmittersReceivers .Flight Instrument System .Roll Control System .Navigation .Communication .Line Replaceable Unit .Flight Management Systems .EquipmentAViring Location Complexities .Radiated Emission .EMC and Aircraft Systems Development .Data Bus Architecture .Line-of-Sight Display and Voice Control .Hypothetical Architecture .Data Bus Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Digital Data Buses .Performance and Status Monitors .Microprocessor Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Avionics Technology Progress .Materials Distribution .1990s ATC Implementation .Probability Versus Consequence .Three-Stage Subsystem Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Projected Criticalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A Discrepancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Postulated Hallmarks of Variances .Microcircuit Tolerance .Noise Margin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252728292930313232333434353539394147515454iv.
1Transient Events .Circuit Noise Rejection (a b c d e D .Circuit Response to EM1.Wiring Categories .Critical Circuits Wire Separation .Selected EM1 Levels .Laboratory Test Setup .ShieldTies .The Grounding Steps .Structure EMC Roles .Details and Installation .The Seven Earth Ground Connections .EMC. Anatomy Block Diagram .Magnetic Field SE of Aluminum .Loss of SE with Joint Finish .SE Comparison .Wire SE Comparison at HF-VHF .Material/Configuration SE Overview .Power Returns .MaterialEesistance Overview .Configuratioflesistance Overview .Resistance Plot-Copper Plane .Resistance Versus Pressure .Joint Finish Resistance .Aircraft and Strap Resonance .Typical Nonmetallic Applications .Graphite-Epoxy Resistance .Graphite-Epoxy SE Shortfall .Graphite-Epoxy Details and Installation .HF-VHFRange .Selected RF Fields: HF-VHF Range .Expected Wire Voltage-Eight Feet .Environments, Safety, and Test .A Transistor Threshold.Representative Coax Voltage Coupling .Representative Secondary Coupling .Graphite-Epoxy or A1 Shielding Added .“H” Field Coupling .“E” Field Coupling .Coupling Versus Separation .Magnetic Fields .Transient Ringing .Electrical lkansients .Layered Design .Trade-Equipment Location .Trade-Wire LengtWSeparation .Trade-Digital Circuits .EM1 Test Limits (SH1.2. 3,4) 42
EXECUTIVE SUMMARYThe Aircraft Electromagnetic Compatibility guidelines document deals with electromagneticcompatibility in a commercial transport aircraft: the specifications, the activities, the design,and the tests to verify and validate compatibility.Objectives are to view architecture, equipment and wiring location, material properties, circuit susceptibilities, and environment as seen from the electromagnetic compatibility designperspective of balanced circuits, filters, electrical bonding, grounding, and shielding.Even today digital electronics are much more common in aircraft. Automated flight controls offuture aircraft will operate under the control of digital clocks, data buses, switching regulators, pulse width modulated power, and radio frequency transmitters on the one hand, and onthe other, sensitive analog and digital instrumentation.Safe and efficient flight will depend on the performance of electronics. It will be important tounderstand the electromagnetic interference types and the electromagnetic interference paths(figure El).TYPEPATHElectrostatic400 HZ/ !l%?i oFigure E- 1 Postulated PercentagesThe EM1 types are set forth in this document by showing a profile of the magnetic and electricfields from power lines; some military, urban, and rural radio frequency field strengths; andthe properties of transients. Significance of the wire circuit return, the balanced circuit,grounding, shielding, and software highlight the protection techniques of a layered designwhich will block paths of electromagnetic interference and maintain interface signal quality.Design specifications, activities, and reviews are proposed to help set up guidelines for equipment verification and aircraft validation.vi
1.0 INTRODUCTION1.1 BACKGROUND AND SCOPE1.1.1 A Case of Engine ShutdownCaptain Hoag thought briefly of the moment when he left home last night. His son, daughter,and wife were all there. They had joked about their planned upcoming vacation, their firsttogether in two years.A voice broke into his short reverie: “Flight 211, you’re low and to the left-please maintain023-you have a cell at 2 o’clock.”Hoag said to the first officer, John Pearson: “John, push it forward and bring ‘er up.”John said: “Gotcha covered. I flew one of these new ones two weeks ago into LoridanInternational-they sure do handle smoothly.”.“Okay-uh huh.” “Gear down.”Flight 211, Atlantic Air, was on approach to Keithrode International Airport (KIA). It was16:45 on October 16. Two hundred and twenty-seven passengers were on board. The weatherhad been partly cloudy with thunderstorms predicted and cell activity in the proximity of theair terminal.Tower: “Flight 211, you are cleared on Runway 3. You are still low.”Captain Hoag: “John, bring ’er up.”A lightning flash occurred off to the left. Then, instantly, a blinding flash, an overwhelmingshudder, and the aircraft metal structure and body seemed to vibrate under a massive pressure and energy wave.Hoag: “We’ve lost number l! Push it all the way forward!”Pearson: “Okay”Hoa
The Aircraft Electromagnetic Compatibility guidelines document deals with electromagnetic compatibility in a commercial transport aircraft: the specifications, the activities, the design, and the tests to verify and validate compatibility. Objectives are to view architecture, equipment and wiring location, material properties, cir-
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ACCOUNTING 0452/11 Paper 1 May/June 2018 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, candidate number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO .
