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Aircraft ElectromagneticCompatibility
Conducted via Interactive Video Teletrainingon the Aviation Training Network (ATN)
Dave WalenFAA Chief Scientific and Technical AdvisorElectromagnetic Interference and Lightning
Federal Aviation AdministrationDecember 4, 2002
Table of Contents
IVT Course Aircraft Electromagnetic CompatibilityFederal Aviation Administration December, 2002 i
GETTING STARTEDHow Do I Use This Guide? ........................................................ 1
I. SYSTEMS ENGINEERING CURRICULUM ...................... 2What Does the Curriculum Cover? ............................................ 2Two-Week Job Function Course ................................................ 3Overviews of Technical Subjects ............................................... 4Core Technical Subjects Courses ............................................... 5
II. IVT COURSE ORIENTATION.............................................. 7About This Course...................................................................... 7Who Is the Target Audience? ..................................................... 7Who Is the Instructor? ................................................................ 8What Will You Learn? ............................................................... 9What Topics Does the Course Cover?........................................10What Are Some Good References? ............................................11
B. Quiz.............................................................................. B-1C. Course Evaluation Form .............................................. C-1
This guide provides you with an overview of the course, how itfits with the rest of the curriculum, an orientation to IVT training,support materials needed during the broadcast, information onhow to use of this guide for the self-study video option, and endof course evaluation forms.Follow these steps to complete your study.1. Read Section I, Systems Engineering Curriculum, to learn
about how this IVT fits within the whole curriculum.2. Review Section II, IVT Course Orientation, before the
broadcast or before you watch the videotape to get anoverview of the purpose of the course, the target audience, theinstructor, what you will learn, how this course will help youon-the-job, the topics covered in the course.
3. Turn to Appendix A, IVT Presentation Visuals. Refer to itduring the broadcast and take notes as needed.
4. Complete the post-course quiz in Appendix B. If watching onthe ATN, you will be prompted to respond using the ATNkeypads.
5. Complete an end-of-course evaluation contained in AppendixC, Course Evaluation Form. For the live broadcast, enter yourresponses on the ATN keypads when prompted. For the videooption, please complete the form and return to your ATM if youwant to receive credit in your training history.
The Systems Engineering Curriculum fits into the broader AIRTraining Program that is summarized in the following figure.
Within the context of the AIR Training Program, the SystemsEngineering Curriculum is designed to effectively meet thecritical safety mission of the FAA by addressing the followingService goals:Standardization
• Promote standardization throughout the organization in taskaccomplishment and application of airworthiness regulationsin order to achieve uniform compliance.
The AIR Training ProgramThe AIR Training ProgramAn Overview
Indoctrination Part 21 Core Job FunctionCommunicating for Success
ASE Systems Job Functiono 2-week Courseo Technical Topics-IVT/Videoo Follow-on Courses
ASI Job Function
ASE AirframeJob Function
ASE PropulsionJob Function
Flight TestJob Function
Recurrent Training
ACSEP
Quality Managementof Designee Workforce
FSO-SpecificTechnical Training
First Year with Aircraft CertificationContinuing Development
• Reduce significantly the time required for newly hiredengineers to attain full job performance proficiency.
Customer Service
• Establish and maintain appropriate, effective, and responsivecommunication, collaboration, leadership, and teamworkwith both internal and external customers.
In addition to the Service goals, the Systems EngineeringCurriculum is designed to provide ASEs with job functiontraining in three domains:
• Tasks and procedures governing the work of engineers indesign approval, technical project management, certificatemanagement, and designee management.
• 14 CFR airworthiness requirements that are the purview ofelectrical and mechanical systems engineers. Generally theyare subpart F of 14 CFR parts 23, 25, 27, and 29.
• Technical subjects essential for all new engineers to meetboth introductory requirements and, later, minimumtechnical proficiency level requirements.
The resulting Systems Engineering Curriculum structureconsists of three main types of training opportunities —1. Two-Week Job Function Course2. Overviews of Technical Subjects3. Follow-on Core Technical Subjects Courses
The Two-Week Job Function Course uses an instructor-led,classroom-based format with lecture, discussion, and individualand group activities. Supporting materials used in the courseinclude print, overhead transparencies, videotapes, job aids, anddocuments and sample reports.
The course is divided into the following two major sections:Week 1
• Certification Tasks — includes design approval, technicalproject management, certification management, and DERmanagement.
Week 2
• 14 CFR Requirements and Key 14 CFR Sections —includes training in the subparts of 14 CFR that apply toelectrical and mechanical systems engineers (subpart F) attwo levels: an overview of those subparts across parts 23,25, 27, and 29; and in-depth discussion of significantsections of the 14 CFRs that are important to the Service.The importance of these sections may stem from problems ininterpretation and application of requirements, technicalcomplexity of a design, “high visibility” projects, or safetyconsiderations that are paramount.
High-level overviews of 13 technical subjects are presented byNRSs or other senior engineers. These overviews are availablein two modes:
• An initial live four-hour IVT satellite broadcast withaccompanying course material is received at eachDirectorate and other downlink sites.
• A Video and Self-Study Training Guide adapted from theinitial IVT presentation available through the DirectorateTraining Manager.
Basic concepts and FAA-specific applications and examples areprovided for each of the following 13 technical subjects:For electrical engineers:
Each technical subject overview is designed to not only provideASEs with the FAA perspective on the topic, but also serve asan indicator of what further training may be needed.
As a follow-on to the Overviews of Technical Subjects, thecurriculum will provide more in-depth training on the followingtwo subject areas:
• Systems Safety Assessment
• Reliability & ProbabilityThese core technical subjects are essential to the technical workof the systems engineer in a regulatory environment regardlessof product or technology. Training in each of the core subjects
will be designed to bring systems engineers to a minimum levelof technical proficiency and to help promote proficiency in theapplication of the technical knowledge in an office workenvironment.Additional technical training for engineers beyond these coresubjects will depend largely on ACO organizational needsstemming from customer requirements, products certified,emerging technology, and the number of staff requiring morespecialized training. In short, the more advanced the technicaltraining required, the more individualized it becomes.Such training topics could be as follows:
Aircraft Electromagnetic Compatibility provides anintroduction to the technical fundamentals and certificationaspects of aircraft electromagnetic compatibility. It removessome of the "black magic" that surrounds the issues related toaircraft EMC, and provides FAA aircraft certification engineerswith a basis for aircraft certification when considering EMC.Through the four-hour Interactive Training format, DaveWalen, FAA Chief Scientific and Technical Advisor,Electromagnetic Interference and Lightning, will focus onelectromagnetic compatibility among systems on an aircraft.The course includes examples of aircraft electromagneticcompatibility problems, problem resolution, and the impact onaircraft certification.
This course does not cover aircraft compatibility with theexternal lightning and high intensity radiated fields (HIRF)environments, topics that were addressed in an earlier IVT. Inaddition, compatibility between circuits within a linereplaceable unit (LRU) and electrical power quality will not beaddressed.
This IVT is designed for new and experienced systems andequipment engineers: avionics/electrical (primary); flight testengineers, and propulsion engineers (secondary).
Mr. Dave Walen is the Chief Scientific And Technical Advisorfor Electromagnetic Interference and Lightning, a position hehas held since he joined the FAA in September, 1996.Mr. Walen specializes in aircraft electromagnetic compatibility,lightning protection, and high density radiated field (HIRF)protection. He is involved in FAA programs for aircraftcertification, continued integrity of aircraft electromagneticprotection, accident investigation, technical electromagneticprotection policy development, and specialized aircraftelectromagnetics training. He participates in the internationalHIRF and lightning protection rulemaking working groupwithin the Aviation Rulemaking Advisory Committee.Prior to working with the FAA, Dave spent 19 years with theBoeing Company. His last assignment at Boeing wasengineering manager for Boeing Commercial Airplane GroupElectromagnetics and Antennas. He managed electromagneticeffects and antennas engineering for 737, 747, 757, 767, and777 airplane models. He has authored and contributed tonumerous technical publications associated with aircraftlightning and high intensity radiated field protection.Mr. Walen graduated in 1977 with a degree in ElectricalEngineering from the University of North Dakota. He iscurrently a member of the RTCA SC-135 Committee forAvionics Environmental and Electromagnetic Test Standards,of the SAE AE2 Lightning Committee, of the Institute ofElectrical and Electronic Engineers (IEEE) (and AssociateEditor - IEEE Electromagnetic Compatibility Transactions).Dave is a Registered Professional Engineer – Electrical,Washington State, and a NARTE-Certified ElectromagneticCompatibility Engineer.
After completing this course you will be able to —1. Define and use appropriately the following terms/concepts:
• Electromagnetic interference (EMI).• Electromagnetic compatibility.• Radio frequency interference.
2. Identify the goals of aircraft EMC.3. Identify EMC factors that need to be considered when
evaluating an application for certification, such as:• Frequency spectrum.• Sources of EMI.• Victims of EMI.• Conducted interference.• Radiated interference.
4. Given a particular aircraft (23, 25, 27, or 29), identifyregulatory requirements that form a framework forevaluating the aircraft’s EMC.
5. Describe key factors in each of the following fourapproaches to aircraft electromagnetic compatibilityverification and identify the advantages and disadvantagesof each:• Equipment qualification.• Operational aircraft functional checks.• Aircraft radio checks.• Radio interference measurements.
6. Evaluate a particular EMC certification situation to identifystrengths and weaknesses.
The following topic outline is intended to give you an overviewof the course content. In addition to this outline, Appendix Aof this guide contains the visual presentation material used bythe instructor during the broadcast.I. IntroductionII. Part 1
a. Terminologyb. Fundamentals of electromagnetic compatibility
Sources of interference Victims of interference Conducted interference paths Radiated interference paths Frequency spectrum Transients
III. Part 2a. Approaches for electromagnetic compatibility (EMC)
Equipment circuit design System installation design Aircraft arrangement and structure design Bonding and grounding
b. Aircraft EMC regulatory requirements Aircraft electromagnetic environment effectsrequirements
System and equipment requirements Portable electronic devices
Aircraft EMC VerificationAircraft testsSystem and equipment qualification
EMC ExamplesWrap-UpReferences
6
Scope of This CourseOriented to aircraft certificationFocus on EMC between systems on aircraft
Aircraft lightning and high intensity radiatedfields (HIRF) environments in earlier IVTearlier IVTCompatibility between circuits within anLRU NOTNOT addressed
EM ElectromagneticEMI Electromagnetic interferenceEMC Electromagnetic compatibilityRF Radio frequencyRFI Radio frequency interferenceHIRF High intensity radiated fields
10
Why Use the Term EMC?
GoalGoal for aircraft design and certificationis to achieve electromagneticachieve electromagneticcompatibilitycompatibility among aircraft systems
EMIEMI and RFIRFI are failures to adequatelyfailures to adequatelyconsider electromagneticconsider electromagneticcompatibilitycompatibility during aircraft andsystem design and installation
Leave EM field theory andMaxwell’s equations to university
engineering curriculum
Fundamentals of EMC
Need to understand -Sources of interferenceVictims of interferenceConducted interference pathsRadiated interference pathsFrequency spectrumTransients
14
Frequency Spectrum
Frequencies we are interested in rangefrom hundreds of hertz (kHz) (power andaudio frequencies) to tens of gigahertz(GHz) (radars and satellite communication)
That’s a factor of a hundred millionbetween low and high frequencies (108)
Aircraft radio systems operate fromabout 100 kHz to 10 GHz
dB is abbreviation for decibelLogarithmicLogarithmic (base 10) expressionexpression foramplitude ratiosFor powerFor power: dB(power) = 10 log10 (P1/P2)For voltage and currentFor voltage and current:
Computer clocksRF oscillatorsSwitching power suppliesElectrical load switchingTransmitter fundamental and harmonicfrequencies
22
Interference Effects -Examples
Tones on audio system and radio receiversNuisance radio squelch breaksProximity sensor state changesDisplay jitterFalse fire and smoke detectionUncommanded control panel switchingFalse navigation system indication
Factors affecting coupling between wires:Spacing between wiresSpacing between wires -closer spacing means more couplingFrequency content of signalsFrequency content of signals -higher frequencies mean more couplingLength that wires are routed togetherLength that wires are routed together -longer length means more couplingProximity of circuit return wiresProximity of circuit return wires -closer return wires mean less coupling
28
Radiated InterferenceRF emissions from electrical or electronicequipment radiated directly from equipmentor from connected signal or power wiresSusceptibility can occur on other electricalor electronic equipment receiving theemissions through radio antennas, or oninterconnecting wires acting as antennasInterference path is through air
Emissions radiatedby avionics systemscan radiate to aircraftantennas through:
WindowsCargo and passengerdoor seamsHatches
RF emissions from avionic system
32
VHF CommunicationRadio Example
VHF communication radio operates from117.975 to 137 MHzVHF receiver sensitivity
RTCA DO-186A requires at least10 microvolt sensitivityActual signals that break squelch can be1 to 2 microvoltsDetectable tones on an active channel may bearound 0.5 microvolts
Physically separate EMI source & victimMove source farther from victim - generallyonly effective for radiated interferenceRevise wiring layout, with separationbetween source and victim wiring
51
Controlling EMI, cont.Electromagnetically separateEMI source and victim
Add shielding to source, source wiring,victim wiringAdd in-line filters and suppression
For EMI, shielding normally applied toLRU cases and wiring
53
Shielding ConceptsFactors influencing shielding effectivenessdepend on frequencies you intend to shield
Quality of shield materialQuality of shield material (optical coverage,resistance)Quality of shield terminations, splices andQuality of shield terminations, splices andjointsjoints (resistance and inductance)
Shield terminations as important asShield terminations as important asshield material itselfshield material itself
23.130123.1301 Function and Installation.Each item of installed equipment must -. . . (d) Function properly when installed.23.130923.1309 Equipment, systems and installation.(a) Each item of equipment, each system, andeach installation: (1) When performing itsintended function, may not adversely affectthe response, operation, or accuracy of any -(i) Equipment essential to safe operation; . . .
62
14 CFR Part 23, cont.
23.143123.1431 Electronic Equipment.(b) Radio and electronic equipment,controls, and wiring must be installed sothat operation of any unit or system ofunits will not adversely affect thesimultaneous operation of any other radioor electronic unit, or system of units,required by this chapter.
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
25.130125.1301 Function and Installation.Each item of installed equipment must -. . . (d) Function properly when installed.25.130925.1309 Equipment, systems and installation.(a) The equipment, systems, and installationswhose functioning is required by thissubchapter, must be designed to ensure thatthey perform their intended functions underany foreseeable operating condition.
66
14 CFR Part 25, cont.
25.135325.1353 Electrical equipment and installations.(a) Electrical equipment, controls, andwiring must be installed so that operationof any one unit or system of units will notadversely affect the simultaneous operationof any other electrical unit or systemessential to the safe operation.
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
25.143125.1431 Electronic equipment.(c) Radio and electronic equipment,controls, and wiring must be installed sothat operation of any one unit or system ofunits will not adversely affect thesimultaneous operation of any other radioor electronic unit, or system of units,required by this chapter.
68
AC 25-7 Flight Test Guidefor Transport Airplanes
Chapter 6. EquipmentChapter 6. EquipmentProvides general EMC flight testguidance for airplane navigationand radio systems
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
AC 25-10 Miscellaneous Non-Required Electrical Equipment
5.f.5.f. Calls out RTCA DO-160 Section 21 tests
5.m(4)5.m(4) Describes interference effects.For airplane ground tests, operatecommunication and navigation equipmentat low, high, and mid-band frequencies.
States that ground EMI tests adequate forfollow-on approvals for like or identicalequipment types
70
Flight Test Requirements forPassenger Entertainment Systems
ANM-100 Policy Memo 2/25/92ANM-100 Policy Memo 2/25/92Flight and ground tests may berequired for initial installationGround tests are adequate forfollow-on approvals
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
14 CFR Part 2727.130127.1301 Function and Installation.Each item of installed equipment must -. . . (d) Function properly when installed.27.130927.1309 Equipment, systems and installation.(a) The equipment, systems, and installationswhose functioning is required by thissubchapter must be designed and installed toensure they perform their intended functionsunder any foreseeable operating condition.
72
14 CFR Part 29
29.130129.1301 Function and Installation.Each item of installed equipment must -. . . (d) Function properly when installed.29.130929.1309 Equipment, systems and installation.(a) The equipment, systems, and installationswhose functioning is required by thissubchapter must be designed and installed toensure they perform their intended functionsunder any foreseeable operating condition.
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
29.135329.1353 Electrical equipment and installations.(a) Electrical equipment, controls, andwiring must be installed so that operationof any one unit or system of units will notadversely affect the simultaneous operationof any other electrical unit or systemessential to safe operation.
74
14 CFR Part 29, cont.
29.143129.1431 Electronic equipment.(b) Radio communication and navigationequipment, controls, and wiring must beinstalled so that operation of any one unitor system of units will not adversely affectthe simultaneous operation of any otherradio or electronic unit, or system of units,required by this chapter.
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
EMC Testing for Rotorcraft withElectronic Engine Controls
Rotorcraft Policy No. ASW-2001-001Rotorcraft Policy No. ASW-2001-001Focuses on non-required equipmentinstalled on rotorcraft with criticalelectronic controls, such as FADECGround and flight EMC tests required forinitial approvalRevises guidance in AC 29-2C MiscellaneousGuidance (MG) 4 and AC 27-1B MG4
Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals
communication and navigation systems atlow, high and mid-band frequencies
– Ground EMC tests OK for follow-on approvals
78
14 CFR Part 91 PortableElectronic DevicesSec. 91.21Sec. 91.21 Portable electronic devices.(a) . . . no person may operate, nor may any operatoror pilot in command of an aircraft allow theoperation of, any portable electronic device . . .(b) Paragraph (a) does not apply to . . . (5) Anyother portable electronic device that the operatorof the aircraft has determined will not causeinterference with the navigation or communicationsystem of the aircraft on which it is to be used.
AdvantagesAdvantagesEquipment tests in lab.Standardized testprocedures andcategoriesConfident equipmentwill have satisfactoryEMC on aircraft
DisadvantagesDisadvantagesNo guarantee of EMC onaircraftConsiders EM emissionsfrom 1 item of equipment,not entire systemDoes not considersusceptibility of otheraircraft systems
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Equipment QualificationStandards
RTCA/DO-160 or EUROCAE/ED-14(these are equivalent)
Equivalent industry standards(for example, Boeing D6-16050-4C)
What about FCC 47 CFR 15?Most consumer electronics meet FCCClass B requirements in 47 CFR 15Test setup and procedures are differentthan DO-160 Section 21Uses open air test site instead ofshielded roomEmission limits are similar to DO-160Section 21 Category L
0
10
20
30
40
50
60
70
80
10 100 1,000Frequency (MHz)
Fiel
d St
reng
th (d
Bµv
/m)
DO-160 Cat B
DO-160 Cat L
FCC and RTCA/DO-160 EmissionLimit Comparison
FCC Part 15Class B
DO-160 levels adjusted for 3 meters separationbetween antenna and equipment under test
AdvantagesAdvantagesUses real aircraftoperating conditionsMost conditions maybe performed duringground testNo special-purposeRF measurementequipment required
DisadvantagesDisadvantagesThorough source-victimtesting time-consumingAcceptance criteria moredifficult to defineSpecial test equipmentrequired to make somesystems function onground
Typically uses a source-victim matrix
98
Aircraft Radio Checks
AdvantagesAdvantagesNo specialequipment requiredMay be performedduring ground test
DisadvantagesDisadvantagesLengthy process to tuneeach channelSelected channel tuningwill miss narrow-bandinterferenceAcceptance criteria mustbe defined
Aircraft radio receivers can be tuned acrosschannels to detect interference
AdvantagesAdvantagesProvides quantitativemeasurement ofinterfering signalsPerform duringground testMay use with radiotuning test
DisadvantagesDisadvantagesAmbient signals maskinterfering signals atspecific test siteDefine acceptance criteriaSpecial test equipmentApplies only to radiointerference
Interfering signals can be measured ataircraft radio receiver antenna connectors
Why Did This Happen?Mode control panel generated RF conductedemissions from internal processor clockRF conducted currents coupled to adjacentlocalizer coax cableLocalizer coax cable conducted RF conductedemissions to the airplane localizer antennasLocalizer receiver detected emissions as avalid localizer signal
System ConfigurationFlap drive, controller and wiring installedbelow rear seatsVHF comm antenna installed on bottomcenterline of airplane, just below flap driveFlap controller wiring to flap drive usesunshielded wiresAirframe primarily fiberglass, withaluminum foil for shielding & grounding
Medical evacuation helicoptercrashed following loss of enginepowerElectromagnetic interference to full-authority digital engine control(FADEC) was suspected
FactsMedevac operation in cruise flightPilot heard a sharp, increasing pitch tonein his headsetPilot placed FADEC switch to MANUALpositionEngine experienced several excursions ofshutdown and re-ignitionsHelicopter autorotated to hard landing
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Helicopter Configuration
Single engine helicopter with singlechannel FADEC
Medical equipment, additional radios,and cell phone installed
Radios and cell phone connected tohelicopter interphone system
1. Achieving electromagnetic compatibility involves:a. Controlling the EMI source system emissions, the electromagnetic
coupling path, and the victim system immunity.b. Black magic.c. Only using equipment that meets RTCA/DO-160.d. Minimizing the use of radios.
2. Common aircraft radio receivers operate in the frequency range from:a. 10 MHz to 100 MHz.b. 100 MHz to 1 GHz.c. 100 kHz to 10 GHz.d. 100 MHz to 100 GHz.
3. Which are possible methods for decreasing VHF communication receiverinterference?a. Decreasing the VHF receiver sensitivity.b. Increasing the separation distance from the interference source to the
VHF antenna.c. Reducing the level of VHF emissions from the interference source.d. All of the above.
4. The terminations for a wire bundle shield are:a. Better if they are very long.b. As important as the shield itself.c. Unimportant.d. Depends on the type of shield.
5. Common sources of RF emissions within avionics equipment are:a. Computer clocksb. RF oscillators.c. Switching power supplies.d. All of these.
6. RF emissions that couple from one wire bundle to an adjacent wire bundlecan be reduced by:a. Shielding the emitting wire bundle.b. Moving the susceptible wire bundle farther from the emitting wire
bundle.c. Both A and B.d. Neither A or B.
7. RF emissions that are conducted on wires from one avionic box to othersystems can be reduced by:a. Modifying the emitting avionics.b. Shielding the wires from the avionics.c. Testing the avionics according to RTCA/DO-160.d. None of these.
8. Which regulations in part 25 specifically mention electromagneticcompatibility?a. 25.1301.b. 25.1309.c. 25.1353.d. None.
9. Which sections of RTCA/DO-160 have test procedures and limits for radiofrequency emissions and susceptibility?a. Sections 2 and 3.b. Sections 8 and 9.c. Sections 20 and 21.d. Sections 22 and 23.
10. Which aircraft EMC tests are commonly used?a. Operational aircraft functional checks.b. Aircraft radio checks.c. Radio interference measurements.d. All of these.
If you are taking this course via IVT/ATN and you are logged onto a keypad, you will be asked to complete the course evaluation byusing the Viewer Response System keypad. Your instructor willprovide directions on how and when to complete the courseevaluation. There are also some open-ended questions that you canrespond to (in writing), and these can be faxed back to the ATNstudio.
If you are completing the course via self-study video, pleasecomplete the form and return to your Air Training Manager (ATM).Please note that to get credit in your training history for watching thevideo, you MUST return the evaluation form.
December, 2002We want your candid opinion on the course you just completed. Your feedback will help us toprovide the best possible products and services. Please respond to the questions below. If youhave completed via IVT, your instructor will prompt you when to enter your answers in yourkeypad. If you have completed the video option, complete this form manually and return toyour ATM. You must complete and return this evaluation form to your ATM in order to getcredit for the video self-study option.
A = Highly Satisfactory B = Satisfactory C = Somewhat SatisfactoryD = Not at all Satisfactory E = Not applicable