Aircraft Electromagnetic Compatibility

Aircraft ElectromagneticCompatibility

Conducted via Interactive Video Teletrainingon the Aviation Training Network (ATN)

Is it BlackBlack MagicMagic?

© 1994 D eneba S ystems, Inc.

Developed and Presented by:

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

APPENDIXA. IVT/Self-Study Presentation Visuals........................... A-1

Introduction.................................................................. A-2Part 1

Terminology......................................................... A-5Fundamentals of EMC ......................................... A-8

Part 2Approaches for EMC ......................................... A-25Aircraft EMC Regulatory Requirements ........... A-32

Part 3Aircraft EMC Verification ................................. A-42Aircraft EMC Examples..................................... A-54EMC IVT Wrap-Up ........................................... A-67

B. Quiz.............................................................................. B-1C. Course Evaluation Form .............................................. C-1

Getting Started

IVT Course Aircraft Electromagnetic CompatibilityFederal Aviation Administration December, 2002 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.

How Do I UseThis Guide?

Systems Engineering Curriculum


I. Systems Engineering Curriculum

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

DACT, OAT

OJTAIR

What Does theCurriculumCover?



Job Performance Proficiency

• 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.

Two-Week JobFunctionCourse



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:

• Advanced Communication/Datalink

• Advanced Display Systems/Heads-Up Displays

• Advanced Navigation

Overviews ofTechnicalSubjects



• Low Visibility

For mechanical engineers:

• Crashworthiness and Interior Compliance

• Doors

• Icing

For both elecrical and mechanical engineers:

• Aircraft Electromagnetic Compatibility

• Automatic Flight Control Systems

• Complex Electronic Hardware

• HIRF/EMI/ Lightning

• Human Factors

• Software

• System Safety Analysis

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

Core TechnicalSubjectsCourses



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:

• HIRF

• Lightning

• Software Fundumentals

• Dynamic Seat Testing

• Icing Certification

• Accident Investigation

• Human Factors

• Flammability

• Interior Compliance & Crashworthiness

IVT Course Orientation


II. IVT Course Orientation

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).

About ThisCourse

Who Is theTarget

Audience?



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.

Who Is theInstructor?

Dave Walen



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.

What WillYou Learn?



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

IV. Part 3a. Aircraft EMC verification

Aircraft tests System and equipment qualification

b. EMC examplesV. Summary and quiz

What TopicsDoes the

Course Cover?



The following references can serve as additional resources inlearning about aircraft electromagnetic compatibility.

C. R. Paul, “Introduction to Electromagnetic Compatibility,”Wiley-InterScience, 1992.

RTCA Document DO-160D, “Environmental Conditions andTest Procedures for Airborne Equipment,” July 29, 1997.

MIL-STD-461E, “Requirements for the Control ofElectromagnetic Interference Characteristics ofSubsystems and Equipment,” 20 August 1999.

IEEE Transactions on Electromagnetic Compatibility,published quarterly.

Proceedings of the IEEE International Symposium onElectromagnetic Compatibility, held August annually inUS or Canada.

H. W. Ott, “Noise Reduction Techniques in ElectronicSystems,” Second Edition, Wiley-Interscience, 1988.

H. Johnson and M. Graham, “High-Speed Digital Design,”Prentice-Hall, 1993.

J. D. Kraus, “Electromagnetics with Applications,” FifthEdition, WCB McGraw-Hill, 1999.

W. L. Stutzman and G. A. Thiele, “Antenna Theory andDesign,” John Wiley and Sons, 1981.

What AreSome GoodReferences?

EMC IVT Visuals Appendix A

IVT Course Aircraft Electromagnetic CompatibilityFederal Aviation Administration December, 2002 Appendix A-1

Appendix A

Aircraft Electromagnetic Compatibility

IVT Presentation Visuals

Introduction EMC IVT Visuals


Introduction

1

AircraftElectromagnetic

Compatibility (EMC)

Dave WalenFAA National Resource Specialist

Electromagnetic Interference and Lightning425-227-1156

[email protected] 2002

2

Course Contents - Part 1TerminologyFundamentals of Electromagnetic Compatibility

Sources of interferenceVictims of interferenceConducted interference pathsRadiated interference pathsFrequency spectrumTransientsPrecipitation static



3

Course Contents - Part 2aApproaches for ElectromagneticCompatibility (EMC)

Equipment circuit design

System installation design

Aircraft arrangement and structure design

Bonding and grounding

4

Course Contents - Part 2b

Aircraft EMC Regulatory RequirementsAircraft electromagnetic environmenteffects requirements

System and equipment requirements

Portable electronic devices



5

Course Contents - Part 3

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

– Usually means LRU will not functioncorrectly

Part 1: Terminology EMC IVT Visuals


Part 1: Terminology

7

Aircraft ElectromagneticEnvironment

Electrical and electronic systemelectromagnetic emissionsSystem electromagnetic transientsLightningHIRFPrecipitation staticElectrostatic discharge

8

Electromagnetic Compatibility

Is it BlackBlack MagicMagic?

No - but effectiveness and performancedepend on many details

© 1994 D eneba S ystems, Inc.



9

Abbreviations

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



Elements of EMI

EMI Source

EMI VictimEMC: Control EMIsource, EM couplingpath, and victimimmunity

Transmission orCoupling Path

11

12

Aircraft EMC GoalsLimit radiated and conductedelectromagnetic emissionsLimit aircraft system susceptibility toelectromagnetic emissions

Ensure appropriate aircraft systemEnsure appropriate aircraft systemperformance in the complex aircraftperformance in the complex aircraft

electromagnetic environmentelectromagnetic environment

Part 1: Fundamentals of EMC EMC IVT Visuals


Part 1: Fundamentals of EMC

13

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



Aircraft and Commercial Radio Spectrum

0.010 0.100 1.000 10.000 100.000

LORAN C

ADFHF

MB

TV 2-6AM

100.000 1000.000

ELT

VHF

ELTGS

ELTVOR

LOC TV 7-13 TV 14-69CELL

PCSFM

1000.000 10000.000Frequency (MHz)

TCASATC GPS

SATCOM RA

MLS

WXR

WXR

DMEPCS

15

16

What is a dB?

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:

dB(voltage) = 20 log10 (V1/V2)dB(current) = 20 log10 (I1/I2)



17

dBs are Ratios

Decibels must be related to a knownvalue to express an specific value

dBmdBm = decibels relative to 1 milliwatt

dBWdBW = decibels relative to 1 watt

dBdBµµvv = decibels relative to 1 microvolt

dBidBi = antenna gain relative to an isotropic antenna

18

Why Use dBs?Good for expressing amplitudes witha wide range of values

Example: RF field strengths on aircraftrange from 1000 volts/meter (v/m) (HIRF)to 1 microvolts/meter for radio receiversA factor of a billion

dBs allow adding and subtracting ratios,instead of multiplying and dividing



19

Some Decibel Equivalents -Power

0.001 10.10.01 10010 1000

-10 dB-20 dB-30 dB 0 dB 10 dB 20 dB 30 dB

Power Ratio

decibels

20

Some Decibel Equivalents -Voltage

0.001 10.10.01 10010 1000

-20 dB-40 dB-60 dB 0 dB 20 dB 40 dB 60 dB

Voltage Ratio

decibels



21

Sources of Interference

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



23

Conducted Interference

RF emissions from electrical orelectronic equipment conducted viasignal or power wires

Susceptibility can occur on otherelectrical or electronic equipmentconnected to signal or power wires

24

Conducted Interference, cont.

Interference path is throughinterconnecting signal or power wires

Reducing conducted susceptibilitytypically requires modifying theemitting avionics, not the shielding



Conducted Interference SourcesConducted emissions to other connected equipmentat 60 kHz + harmonics, 10 MHz + harmonics,33 MHz + harmonics

33 MHz + harmonics (66MHz, 99 MHz, 132 MHz, etc.)


Switched-Mode PowerSupply

60 kHz(60 kHz + harmonics)(120 kHz, 180 kHz, etc.)

Processor33 MHz

DisplayDriver10 MHz

28 VDCData bus,Discrete logic,Control signals,Analog signals

25

Wire to Wire Coupling

To 28VDC

ToStructure

ConductedEmission Source Current

MagneticFields

Conducted RFemissions may couplefrom source wires to

adjacent wires

26



27

Wire to Wire Coupling, cont.

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



Radiated Emission SourcesRadiated emissions from LRU enclosure

and wires at 10 MHz + harmonics,33 MHz + harmonics

29



Switched-Mode PowerSupply

60 kHz(60 kHz + harmonics)(120 kHz, 180 kHz, etc.)

Processor33 MHz

DisplayDriver10 MHz

28 VDCData bus,Discrete logic,Control signals,Analog signals

Radiated Emission Coupling to Wires

To 28 VDC ToStructure

Emission Source

RF emissionson wires

RadiatedFields

RF Emissionsfrom LRU case

30



31

Very High Frequency(VHF) Communication Antenna

RF Emissions ReceivedBy Antennas

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



33

DO-160 Emissions forVHF FrequenciesRTCA/DO-160 Section 21 defines categoriesfor RF emissions in VHF comm bands

Cat B allows ~ 2000 microvolts per meterCat L allows ~ 200 microvolts per meter

38 to 53 dB minimum path loss betweensystem in transport airplane cabin andVHF receiver (from RTCA/DO-233)

34

VHF CommunicationInterference Results

Aircraft system can have emissionsreceived by VHF

Section 21 Cat B — 4.5 to 25 microvoltsSection 21 Cat L — 0.5 to 2.5 microvolts

Compare this with receiver sensitivitythat ranges from 0.5 to 2 microvolts!



35

Methods for LimitingRadio Interference

Methods include:Decreasing radio receiver sensitivity(reduces communication range)

Increasing separation distance frominterference source to radio antennaReducing level of RF emissions frominterference source (preferred method)

36

Pulses and Spectrum

Rise time and fall time of pulsesdetermine spectral power

Shorter rise (and fall) times produceShorter rise (and fall) times producehigher frequency contenthigher frequency content

Not just frequency of fundamentalsignal, but also rise time of signal



37

Pulse Waveform

0

0.2

0.4

0.6

0.8

1

-10 0 10 20 30 40 50 60 70Time (microseconds)

Cur

rent

(A)

38

Pulse Spectrum

1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E+02 1.00E+04 1.00E+06 1.00E+08Frequency (Hz)

Am

plitu

de (A

/Hz)



39

Example - InductiveSwitching Transients

To 28 VDC ToStructure

Relay CoilSwitchCurrent

MagneticFields

40

Electromagnetic Transients

Fast transients ⇔ high frequency content

Frequency Frequency →→Time Time →→

⇔⇔



41

Transient Generation

Sources of electromagnetic transientsand pulses

Switching inductive loads

Electrostatic discharges

Power bus switching

Lightning

42

Precipitation Static(P-Static)

Interference



43

Precipitation Static Interference

Result of high-voltage aircraftcharging fromsnow, ice, rainand dust

Effects include:Radio noiseVisible corona (St. Elmo’s fire)Puncture through insulatingmaterials (radomes & windows)

- -

- -

- -

+-

+

+

-- -

44

What is P-Static?Impact of particles separates electricalcharge from particles, so aircraftacquires charge

High-voltage corona discharge fromaircraft extremitiesHigh-voltage flashover across insulatingstructureArcs between isolated metal panels



45

Controlling P-StaticInterference

Static dischargers (wicks)Discharge lower voltage than natural coronaReduce radio noise

Resistive paints on non-conductingsurfaces, such as fiberglass fairings

Electrical bonding metal structure & panels

Rounding sharp corners of antennas

Part 2: Approaches for EMC EMC IVT Visuals


Part 2: Approaches for EMC

46


Part 2

47

Course Contents - Part 2a

Approaches for ElectromagneticCompatibility

Equipment circuit design

System installation design

Aircraft arrangement and structure design

Bonding and grounding



48

Course Contents - Part 2b

Aircraft EMC Regulatory RequirementsAircraft electromagnetic environmenteffects requirements

System and equipment requirements

Portable electronic devices

49

Approaches forElectromagnetic

Compatibility



50

Controlling EMI

Limit EMI sourcesCircuit design, filter, change operatingfrequencies

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

Protect (harden) EMI victimCircuit design, filters, wiring layoutChange operating frequencies



52

ShieldingCan be applied to:

Circuit componentsWiresWire bundlesLRU casesStructure

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



54

Shielding Concepts, cont.

Beware of data showing shieldingeffectiveness of shield materialalone or claims of shielding greaterthan 40 dB

Claims probably haven’t consideredshield terminations

Shielded WiresShielded Wires

Shields over wires must be terminated with lowresistance and inductance at all connectors

Except for some specific cases on audio wiring

55

Effective shieldEffective shield -terminated at both ends

Ineffective shieldIneffective shield - notterminated at both ends



56

Electrical Bonding andGroundingGround Strap

orBondingJumper

Bonding jumpersBonding jumpers and ground strapsground strapsmay be used to control

electromagnetic interference

57

Electrical Bonding

Electrical bonding provides a controlledcurrent path between equipment andaircraft structureElectrical bonding may be required for:

System performanceElectrical fault protectionElectromagnetic compatibility



58

Bonding Effectiveness

For electromagnetic compatibility,bonding jumpers must have:

Low resistanceLow inductance

Low inductance means length must be shortAs EMI signal frequency increases,impedance created by inductance increases

Part 2: Aircraft EMC Regulatory Requirements EMC IVT Visuals


Part 2: Aircraft EMC Regulatory Requirements

59

Aircraft EMCRegulatory

Requirements

60

Aircraft EMC RegulatoryRequirements

The wordselectromagnetic compatibility

are are NOTNOT written in the regulations written in the regulations



61

14 CFR Part 23

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.



63

AC 23-8A Flight Test Guidefor Part 23 Airplanes

Chapter 5. EquipmentChapter 5. EquipmentProvides general EMC flight testguidance for airplane navigation andradio systems

Specifies HF radio interference testsat 1 MHz intervals

64

AC 23-15 Small AirplaneCertification Compliance

4.v. Avionics Installation4.v. Avionics InstallationMentions interference tests, but notspecifically EMC



65

14 CFR Part 25

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


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.



67


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



69

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



71

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.



73


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


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.



75

14 CFR Part 29 ACsAC 29-2AC 29-2 Certification of TransportCategory Rotorcraft

AC 29.135329.1353 Electrical Equipment andInstallations– Recommends RTCA DO-160

AC 29.1431AC 29.1431 Electronic EquipmentAC 29 MG1AC 29 MG1 Certification Procedure forRotorcraft Avionics Equipment– Mentions EMC flight tests

76

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



77

AC 43.13-1B AircraftInspection and RepairChapter 11 Aircraft Electrical SystemsChapter 11 Aircraft Electrical Systems

Section 15.Section 15. Grounding and BondingSection 8.Section 8. Wiring Installation InspectionRequirements

–– 11-10611-106 Electromagnetic Interference–– 11-10711-107 Interference Tests - Operate

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.

Part 3: Aircraft EMC Verification EMC IVT Visuals


Part 3: Aircraft EMC Verification

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Part 3

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Course Contents - Part 3

Aircraft EMC VerificationAircraft testsSystem and equipment qualification

EMC ExamplesWrap-UpReferences



81

Aircraft EMC Verification

82

EMC Verification Approaches

Equipment qualification

Operational aircraft functional checks

Aircraft radio checks

Radio interference measurements



83

Equipment laboratory tests, such as RTCA/DO-160

Equipment Qualification

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

84

Equipment QualificationStandards

RTCA/DO-160 or EUROCAE/ED-14(these are equivalent)

Equivalent industry standards(for example, Boeing D6-16050-4C)

TSO-specific requirements

MIL-STD-461



85

RTCA/DO-160 EMCRequirements

RF Emissions - Section 21Installed equipment should meet this orequivalent

RF Susceptibility - Section 20May include high level HIRF tests

Audio and Induced Signal Susceptibility- Sections 18 and 19

86

RTCA/DO-160 Section 21

Measures RF emissionsConducted on signal and power wiresRadiated from LRU and wires

Four emissions categories (B, L, M & H)Category B limits allow 10 times higheremissions than other categories



20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

1 10 100 1,000 10,000

Frequency (MHz)

RF

Emis

sion

(dBµv

/m)

Category B

Category L

RTCA/DO-160D Section 21 Categories B and L Radiated

87

RTCA/DO-160D Section 21 Category M Radiated

20.030.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

1 10 100 1,000 10,000Frequency (MHz)

RF

Emis

sion

(dBµv

/m)

Category M

88



RTCA/DO-160D Section 21 Category H Radiated

20.030.0

40.050.0

60.0

70.0

80.0

90.0

100.0

1 10 100 1,000 10,000Frequency (MHz)

Category H

89

RF

Emis

sion

(dBµ v

/m)

RTCA/DO-160D Section 21Categories B, L, M, & H Conducted

0.0

10.020.0

30.0

40.050.0

60.070.080.090.0

100.0

0.1 1 10 100Frequency (MHz)

Category B Power WiresCategories L, M, & H Interconnecting Wires

Categories L, M, & H Power Wires

Category B Interconnecting Wires

RF

Emis

sion

(dBµv

/m)

90



Measured RF Conducted Emissions

Category M150 kHz to 100 MHz

91

Measured RF Radiated Emissions

92

Category MVertical Antenna Polarization

25 to 200 MHz



93

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

94



95

Other SectionsAudio susceptibility - Sections 18 & 19

Determines if equipment can withstandpower and audio frequency conductedinterference

Inductive switching transients - Section 19Determines if equipment can withstandtransients typical during inductive loadswitching

Inductive Switching Transient

200 v

20µs

96



97

Operation AircraftFunctional Checks

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



99

Radio Channels - Examples

VHF comm 25 kHz spacing -760 channels

VHF comm 8.33 kHz spacing -2280 channels

Localizer - 40 channels

Glide slope - 40 channels

100

Acceptance Considerations

VHF commNo unintended squelch breaksNo audio tones that interfere withcommunications

Localizer, glide slope, and VORNo guidance errorsNo audio tones to interfere with station ID



101

Radio InterferenceMeasurements

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

Part 3: Aircraft EMC Examples EMC IVT Visuals


Part 3: Aircraft EMC Examples

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Aircraft EMC Examples

103

Example 1

Transport Airplane LocalizerInterference



104

Transport AirplaneLocalizer Interference

During Category 1 autoland airplanediverged left of runway center line

No autoland warning annunciated

-10

-5

0

5

10

15

20

1.08E+08 1.10E+08 1.12E+08 1.14E+08 1.16E+08 1.18E+08Frequency (Hz)

Airp

lane

Loc

aliz

er A

nten

naSi

gnal

dB

(uV)

Airport Localizer Signal

RF Interference Measured atLocalizer Receiver

105



-25-20-15

-10-505

101520

1.08E+08 1.10E+08 1.12E+08 1.14E+08 1.16E+08 1.18E+08Frequency (Hz)

Con

trol

Pan

el W

ire B

undl

e C

urre

nt d

B( µ

A)

Current Measured onControl Panel Wire Bundle

106

107

System ConfigurationAirplane had autopilot with modecontrol panel

Mode control panel wire bundles routedadjacent to weather radar wire bundles

Weather radar wire bundles routedthrough nose bulkhead to weather radar,where localizer antennas installed



108

System Configuration, cont.

ModeControlPanel

LocalizerAntenna

109

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



110

Example 2

Small Airplane Flap ControlInterference

111

Small Airplane Flap Control

Electronic flap position controllermalfunctioned during VHF commradio use

During flap actuation, flaps would stop atuncommanded positions or reverse ifpilot transmitted on VHF comm radio



112

113

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



114

System Description

Flap actuator used electrical motor-driven jackscrew

Flaps have three positions: stowed,mid-extension, and full extension

Magnetic proximity sensor used todetect position of jackscrew

115

System Description, cont.

Electronic flap controller usedpilot flap switch and magneticsensors to command jackscrewmotor

Electronic flap controller usedTTL circuit logic to control andcommand flap position



116

System Schematic

Electronic FlapController

Flap Actuator Motor

Magnetic JackscrewPosition Sensor

Cockpit Flap Position Switch

VHF CommTransceiver

VHF CommAntenna

117

Why Did This Happen?VHF comm transmitter induced RF currenton flap control wires

RF current was conducted into flap controllerand was rectified by TTL circuit elements

Rectified RF currents were interpreted asa logic change by the TTL circuit elements

Flap controller was not test for RF susceptibility



118

Changes Required

Simultaneous flap operation andcomm transmission prohibited

Service bulletin created to add EMIsuppression to flap system wiring

Ferrite cores added to flap control wiring

119

Example 3

Helicopter Audio Interference



120

Helicopter AudioInterference

Medical evacuation helicoptercrashed following loss of enginepowerElectromagnetic interference to full-authority digital engine control(FADEC) was suspected

121



122

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

123

Helicopter Configuration

Single engine helicopter with singlechannel FADEC

Medical equipment, additional radios,and cell phone installed

Radios and cell phone connected tohelicopter interphone system



124

Cell Phone Configuration

Helicopter audiointerphone system

Helicopter tocell phone

voltageconverter

Pilot’sheadset

Cell phone base

Cell phonevoltage converter Helicopter

power

125

Why Did This Happen?Cell phone voltage converterinstalled under cabin floor

Corrosion on voltage convertercircuit card resulted in voltageconverter audio oscillation

Audio oscillation conducted onpower wires to cell phone base



126

Impact of Audio InterferenceAudio oscillation coupled to interphone,resulted in audio tone on pilot’s headsetPilot apparently interpreted audio toneas FADEC FAIL warningPilot selected FADEC MANUAL modeRotor RPM exceeded limits, resulting inautomatic engine shutdown

127

Implications

Non-essential, non-requiredsystems can have impact onrequired systems

Even nuisance audio EMI canresult in unsafe conditions

Part 3: EMC IVT Wrap-Up EMC IVT Visuals


Part 3: EMC IVT Wrap-Up

128

EMC IVT Wrap-Up

Focused on electromagneticcompatibility, not lightning and HIRFEMC fundamentals reviewRegulatory basis for EMCApproaches to complianceExamples

EMC IVT Quiz Appendix B

IVT Course Aircraft Electromagnetic CompatibilityFederal Aviation Administration December, 2002 Appendix B-1

Appendix B

Aircraft Electromagnetic Compatibility

Quiz



QUIZ

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.

Evaluation Appendix C

IVT Course Aircraft Electromagnetic CompatibilityFederal Aviation Administration December, 2002 Appendix C-1

Appendix C

Course Evaluation Form

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.



IVT or Self-Study VideoEvaluation Form

Aircraft Electromagnetic CompatibilityIVT Course # 62835; Video/Self-study # 25835

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

_____________________________________________________________

1. Clarity of objectives A B C D E

2. Clarity of instructions A B C D E

3. Ease of navigation A B C D E

4. Relevance of content to your job A B C D E

5. Relevance of exercises to your job A B C D E

6. Effectiveness of presentation of content A B C D E

7. Quality of feedback A B C D E

8. Quality of instructor/student communication A B C D E

9. Supervisor support in course completion A B C D E

10. Overall quality of the course A B C D E



Aircraft Electromagnetic CompatibilityIVT Course # 62835; Video/Self-study # 25835

December, 2002(This page is optional: complete manually)

What information was most useful to you and why?

What information was least useful to you and why?

Additional comments:

If completing this page after participating in the live ATN broadcast, pleasefax this sheet to the ATN studio at 405 954-0317.

If completing the previous page and this one after watching the video, send toyour AIR Training Manager (ATM) to get credit in your training history.

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Aircraft Electromagnetic Compatibility