Aircraft Electromagnetic Compatibility

Aircraft Electromagnetic Compatibility Conducted via Interactive Video Teletraining on the Aviation Training Network (ATN)

Is it Black Magic?

©

1994 D eneba S ystems,

Inc.

Developed and Presented by:

Dave Walen FAA Chief Scientific and Technical Advisor Electromagnetic Interference and Lightning

Federal Aviation Administration December 4, 2002

Table of Contents GETTING STARTED How Do I Use This Guide? ........................................................ 1 I.

SYSTEMS ENGINEERING CURRICULUM ...................... What Does the Curriculum Cover? ............................................ Two-Week Job Function Course ................................................ Overviews of Technical Subjects ............................................... Core Technical Subjects Courses ...............................................

2 2 3 4 5

II. IVT COURSE ORIENTATION.............................................. 7 About This Course...................................................................... 7 Who Is the Target Audience? ..................................................... 7 Who Is the Instructor? ................................................................ 8 What Will You Learn? ............................................................... 9 What Topics Does the Course Cover?........................................10 What Are Some Good References? ............................................11 APPENDIX A. IVT/Self-Study Presentation Visuals........................... A-1 Introduction.................................................................. A-2 Part 1 Terminology......................................................... A-5 Fundamentals of EMC ......................................... A-8 Part 2 Approaches for EMC ......................................... A-25 Aircraft EMC Regulatory Requirements ........... A-32 Part 3 Aircraft EMC Verification ................................. A-42 Aircraft EMC Examples..................................... A-54 EMC IVT Wrap-Up ........................................... A-67 B. Quiz.............................................................................. B-1 C. Course Evaluation Form .............................................. C-1

IVT Course Federal Aviation Administration

December, 2002

Aircraft Electromagnetic Compatibility i

Getting Started How Do I Use This Guide?

This guide provides you with an overview of the course, how it fits with the rest of the curriculum, an orientation to IVT training, support materials needed during the broadcast, information on how to use of this guide for the self-study video option, and end of 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 an overview of the purpose of the course, the target audience, the instructor, what you will learn, how this course will help you on-the-job, the topics covered in the course. 3. Turn to Appendix A, IVT Presentation Visuals. Refer to it during the broadcast and take notes as needed. 4. Complete the post-course quiz in Appendix B. If watching on the ATN, you will be prompted to respond using the ATN keypads. 5. Complete an end-of-course evaluation contained in Appendix C, Course Evaluation Form. For the live broadcast, enter your responses on the ATN keypads when prompted. For the video option, please complete the form and return to your ATM if you want to receive credit in your training history.


December, 2002

Aircraft Electromagnetic Compatibility 1

Systems Engineering Curriculum

I.

Systems Engineering Curriculum

What Does the Curriculum Cover?

The Systems Engineering Curriculum fits into the broader AIR Training Program that is summarized in the following figure.

The AIR Training Program An Overview ASE Systems Job Function o 2-week Course o Technical Topics-IVT/Video o Follow-on Courses

Recurrent Training

ASI Job Function

AIR Indoctrination

Part 21

Core Job Function Communicating for Success

ASE Airframe Job Function

ASE Propulsion Job Function

ACSEP

OJT

Quality Management of Designee Workforce

FSO-Specific Technical Training DACT, OAT

Flight Test Job Function

First Year with Aircraft Certification Continuing Development

Within the context of the AIR Training Program, the Systems Engineering Curriculum is designed to effectively meet the critical safety mission of the FAA by addressing the following Service goals: Standardization • Promote standardization throughout the organization in task accomplishment and application of airworthiness regulations in order to achieve uniform compliance.


December, 2002


Systems Engineering Curriculum Job Performance Proficiency • Reduce significantly the time required for newly hired engineers to attain full job performance proficiency. Customer Service • Establish and maintain appropriate, effective, and responsive communication, collaboration, leadership, and teamwork with both internal and external customers. In addition to the Service goals, the Systems Engineering Curriculum is designed to provide ASEs with job function training in three domains: • Tasks and procedures governing the work of engineers in design approval, technical project management, certificate management, and designee management. • 14 CFR airworthiness requirements that are the purview of electrical and mechanical systems engineers. Generally they are subpart F of 14 CFR parts 23, 25, 27, and 29. • Technical subjects essential for all new engineers to meet both introductory requirements and, later, minimum technical proficiency level requirements. The resulting Systems Engineering Curriculum structure consists of three main types of training opportunities — 1. Two-Week Job Function Course 2. Overviews of Technical Subjects 3. Follow-on Core Technical Subjects Courses Two-Week Job The Two-Week Job Function Course uses an instructor-led, classroom-based format with lecture, discussion, and individual Function and group activities. Supporting materials used in the course Course include print, overhead transparencies, videotapes, job aids, and documents and sample reports.


December, 2002


Systems Engineering Curriculum The course is divided into the following two major sections: Week 1 • Certification Tasks — includes design approval, technical project management, certification management, and DER management. Week 2 • 14 CFR Requirements and Key 14 CFR Sections — includes training in the subparts of 14 CFR that apply to electrical and mechanical systems engineers (subpart F) at two levels: an overview of those subparts across parts 23, 25, 27, and 29; and in-depth discussion of significant sections of the 14 CFRs that are important to the Service. The importance of these sections may stem from problems in interpretation and application of requirements, technical complexity of a design, “high visibility” projects, or safety considerations that are paramount.

Overviews of Technical Subjects

High-level overviews of 13 technical subjects are presented by NRSs or other senior engineers. These overviews are available in two modes: • An initial live four-hour IVT satellite broadcast with accompanying course material is received at each Directorate and other downlink sites. • A Video and Self-Study Training Guide adapted from the initial IVT presentation available through the Directorate Training Manager. Basic concepts and FAA-specific applications and examples are provided for each of the following 13 technical subjects: For electrical engineers: • Advanced Communication/Datalink • Advanced Display Systems/Heads-Up Displays • Advanced Navigation


December, 2002


Systems Engineering Curriculum • 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 provide ASEs with the FAA perspective on the topic, but also serve as an indicator of what further training may be needed.

Core Technical As a follow-on to the Overviews of Technical Subjects, the curriculum will provide more in-depth training on the following Subjects two subject areas: Courses • Systems Safety Assessment • Reliability & Probability These core technical subjects are essential to the technical work of the systems engineer in a regulatory environment regardless of product or technology. Training in each of the core subjects IVT Course Federal Aviation Administration

December, 2002


Systems Engineering Curriculum will be designed to bring systems engineers to a minimum level of technical proficiency and to help promote proficiency in the application of the technical knowledge in an office work environment. Additional technical training for engineers beyond these core subjects will depend largely on ACO organizational needs stemming from customer requirements, products certified, emerging technology, and the number of staff requiring more specialized training. In short, the more advanced the technical training 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


December, 2002


IVT Course Orientation

II. IVT Course Orientation About This Aircraft Electromagnetic Compatibility provides an Course introduction to the technical fundamentals and certification aspects of aircraft electromagnetic compatibility. It removes some of the "black magic" that surrounds the issues related to aircraft EMC, and provides FAA aircraft certification engineers with a basis for aircraft certification when considering EMC. Through the four-hour Interactive Training format, Dave Walen, FAA Chief Scientific and Technical Advisor, Electromagnetic Interference and Lightning, will focus on electromagnetic compatibility among systems on an aircraft. The course includes examples of aircraft electromagnetic compatibility problems, problem resolution, and the impact on aircraft certification. This course does not cover aircraft compatibility with the external lightning and high intensity radiated fields (HIRF) environments, topics that were addressed in an earlier IVT. In addition, compatibility between circuits within a line replaceable unit (LRU) and electrical power quality will not be addressed.

Who Is the This IVT is designed for new and experienced systems and Target equipment engineers: avionics/electrical (primary); flight test Audience? engineers, and propulsion engineers (secondary).


December, 2002


IVT Course Orientation Who Is the Instructor?

Dave Walen

Mr. Dave Walen is the Chief Scientific And Technical Advisor for Electromagnetic Interference and Lightning, a position he has 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 aircraft certification, continued integrity of aircraft electromagnetic protection, accident investigation, technical electromagnetic protection policy development, and specialized aircraft electromagnetics training. He participates in the international HIRF and lightning protection rulemaking working group within the Aviation Rulemaking Advisory Committee. Prior to working with the FAA, Dave spent 19 years with the Boeing Company. His last assignment at Boeing was engineering manager for Boeing Commercial Airplane Group Electromagnetics and Antennas. He managed electromagnetic effects and antennas engineering for 737, 747, 757, 767, and 777 airplane models. He has authored and contributed to numerous technical publications associated with aircraft lightning and high intensity radiated field protection. Mr. Walen graduated in 1977 with a degree in Electrical Engineering from the University of North Dakota. He is currently a member of the RTCA SC-135 Committee for Avionics Environmental and Electromagnetic Test Standards, of the SAE AE2 Lightning Committee, of the Institute of Electrical and Electronic Engineers (IEEE) (and Associate Editor - IEEE Electromagnetic Compatibility Transactions). Dave is a Registered Professional Engineer – Electrical, Washington State, and a NARTE-Certified Electromagnetic Compatibility Engineer.


December, 2002


IVT Course Orientation What Will You Learn?

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), identify regulatory requirements that form a framework for evaluating the aircraft’s EMC. 5. Describe key factors in each of the following four approaches to aircraft electromagnetic compatibility verification and identify the advantages and disadvantages of each: •

Equipment qualification.

•

Operational aircraft functional checks.

•

Aircraft radio checks.

•

Radio interference measurements.

6. Evaluate a particular EMC certification situation to identify strengths and weaknesses.


December, 2002


IVT Course Orientation What Topics Does the Course Cover?

The following topic outline is intended to give you an overview of the course content. In addition to this outline, Appendix A of this guide contains the visual presentation material used by the instructor during the broadcast. I. II.

III.

IV.

V.


Introduction Part 1 a. Terminology b. Fundamentals of electromagnetic compatibility ¾ Sources of interference ¾ Victims of interference ¾ Conducted interference paths ¾ Radiated interference paths ¾ Frequency spectrum ¾ Transients Part 2 a. Approaches for electromagnetic compatibility (EMC) ¾ Equipment circuit design ¾ System installation design ¾ Aircraft arrangement and structure design ¾ Bonding and grounding b. Aircraft EMC regulatory requirements ¾ Aircraft electromagnetic environment effects requirements ¾ System and equipment requirements ¾ Portable electronic devices Part 3 a. Aircraft EMC verification ¾ Aircraft tests ¾ System and equipment qualification b. EMC examples Summary and quiz

December, 2002


IVT Course Orientation What Are Some Good References?

The following references can serve as additional resources in learning about aircraft electromagnetic compatibility. C. R. Paul, “Introduction to Electromagnetic Compatibility,” Wiley-InterScience, 1992. RTCA Document DO-160D, “Environmental Conditions and Test Procedures for Airborne Equipment,” July 29, 1997. MIL-STD-461E, “Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment,” 20 August 1999. IEEE Transactions on Electromagnetic Compatibility, published quarterly. Proceedings of the IEEE International Symposium on Electromagnetic Compatibility, held August annually in US or Canada. H. W. Ott, “Noise Reduction Techniques in Electronic Systems,” Second Edition, Wiley-Interscience, 1988. H. Johnson and M. Graham, “High-Speed Digital Design,” Prentice-Hall, 1993. J. D. Kraus, “Electromagnetics with Applications,” Fifth Edition, WCB McGraw-Hill, 1999. W. L. Stutzman and G. A. Thiele, “Antenna Theory and Design,” John Wiley and Sons, 1981.


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EMC IVT Visuals

Appendix A

Appendix A Aircraft Electromagnetic Compatibility IVT Presentation Visuals


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Aircraft Electromagnetic Compatibility Appendix A-1

Introduction

EMC IVT Visuals

Introduction

Aircraft Electromagnetic Compatibility (EMC) Dave Walen FAA National Resource Specialist Electromagnetic Interference and Lightning 425-227-1156 [email protected] December 2002 1

Course Contents - Part 1 X

Terminology

X

Fundamentals of Electromagnetic Compatibility z

Sources of interference

z

Victims of interference

z

Conducted interference paths

z

Radiated interference paths

z

Frequency spectrum

z

Transients

z

Precipitation static 2


December, 2002


Introduction

EMC IVT Visuals

Course Contents - Part 2a X

Approaches for Electromagnetic Compatibility (EMC) z

Equipment circuit design

z

System installation design

z

Aircraft arrangement and structure design

z

Bonding and grounding

3

Course Contents - Part 2b X

Aircraft EMC Regulatory Requirements z

Aircraft electromagnetic environment effects requirements

z

System and equipment requirements

z

Portable electronic devices

4


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Introduction

EMC IVT Visuals


Aircraft EMC Verification z

Aircraft tests

z

System and equipment qualification

X

EMC Examples

X

Wrap-Up

X

References

5

Scope of This Course X

Oriented to aircraft certification

X

Focus on EMC between systems on aircraft z

z

Aircraft lightning and high intensity radiated fields (HIRF) environments in earlier IVT Compatibility between circuits within an LRU NOT addressed –

Usually means LRU will not function correctly

6


December, 2002


Part 1: Terminology

EMC IVT Visuals

Part 1: Terminology

Aircraft Electromagnetic Environment X Electrical

and electronic system electromagnetic emissions X System electromagnetic transients X Lightning X HIRF X Precipitation static X Electrostatic discharge 7

Electromagnetic Compatibility

Is it Black Magic?

No - but effectiveness and performance depend on many details ©

1994 D eneba S ystems, Inc.

8


December, 2002


Part 1: Terminology

EMC IVT Visuals

Abbreviations X

EM

Electromagnetic

X

EMI

Electromagnetic interference

X

EMC Electromagnetic compatibility

X

RF

Radio frequency

X

RFI

Radio frequency interference

X

HIRF High intensity radiated fields 9

Why Use the Term EMC? X

X

Goal for aircraft design and certification is to achieve electromagnetic compatibility among aircraft systems EMI and RFI are failures to adequately

consider electromagnetic compatibility during aircraft and system design and installation 10


December, 2002


Part 1: Terminology

EMC IVT Visuals

Elements of EMI EMI Source

Transmission or Coupling Path

EMC: Control EMI source, EM coupling path, and victim immunity

EMI Victim

11

Aircraft EMC Goals X

X

Limit radiated and conducted electromagnetic emissions Limit aircraft system susceptibility to electromagnetic emissions

Ensure appropriate aircraft system performance in the complex aircraft electromagnetic environment 12


December, 2002


Part 1: Fundamentals of EMC

EMC IVT Visuals


Fundamentals of EMC X

Need to understand z

Sources of interference

z

Victims of interference

z

Conducted interference paths

z

Radiated interference paths

z

Frequency spectrum

z

Transients

Leave EM field theory and Maxwell’s equations to university engineering curriculum

13

Frequency Spectrum X

Frequencies we are interested in range from hundreds of hertz (kHz) (power and audio frequencies) to tens of gigahertz (GHz) (radars and satellite communication) z

X

That’s a factor of a hundred million between low and high frequencies (108)

Aircraft radio systems operate from about 100 kHz to 10 GHz 14


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EMC IVT Visuals

Aircraft and Commercial Radio Spectrum ADF

0.010 FM

LOC

AM

0.100

TV 2-6

1.000

VHF ELT

MB

HF

LORAN C

10.000

GS

TV 7-13

ELT

VOR

ELT

100.000

TV 14-69

PCS CELL

100.000

1000.000

SATCOM DME PCS TCAS GPS ATC

1000.000

RA

WXR WXR

MLS

Frequency (MHz)

10000.000

15

What is a dB? X

dB is abbreviation for decibel z

Logarithmic (base 10) expression for amplitude ratios

z

For power: power dB(power) = 10 log10 (P1/P2)

z

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

16


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EMC IVT Visuals

dBs are Ratios X

Decibels must be related to a known value to express an specific value z

dBm = decibels relative to 1 milliwatt

z

dBW = decibels relative to 1 watt

z

dBµ dBµv = decibels relative to 1 microvolt

z

dBi

= antenna gain relative to an isotropic antenna 17

Why Use dBs? X

Good for expressing amplitudes with a wide range of values z

z

X

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

dBs allow adding and subtracting ratios, instead of multiplying and dividing 18


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EMC IVT Visuals

Some Decibel Equivalents Power decibels -30 dB -20 dB -10 dB

0.001

0.01

0.1

0 dB

10 dB

1

10

20 dB 30 dB

100

1000

Power Ratio

19

Some Decibel Equivalents Voltage decibels -60 dB -40 dB -20 dB

0.001

0.01

0.1

0 dB

1

20 dB

10

40 dB

60 dB

100

1000

Voltage Ratio

20


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EMC IVT Visuals

Sources of Interference X

Computer clocks

X

RF oscillators

X

Switching power supplies

X

Electrical load switching

X

Transmitter fundamental and harmonic frequencies

21

Interference Effects Examples X X X X X X X

Tones on audio system and radio receivers Nuisance radio squelch breaks Proximity sensor state changes Display jitter False fire and smoke detection Uncommanded control panel switching False navigation system indication 22


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EMC IVT Visuals

Conducted Interference X

X

RF emissions from electrical or electronic equipment conducted via signal or power wires Susceptibility can occur on other electrical or electronic equipment connected to signal or power wires

23

Conducted Interference, cont. X

X

Interference path is through interconnecting signal or power wires Reducing conducted susceptibility typically requires modifying the emitting avionics, not the shielding

24


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EMC IVT Visuals

Conducted Interference Sources Conducted emissions to other connected equipment at 60 kHz + harmonics, 10 MHz + harmonics, 33 MHz + harmonics 33 MHz + harmonics (66 MHz, 99 MHz, 132 MHz, etc.)

28 VDC Data bus, Discrete logic, Control signals, Analog signals

Switched-Mode Power Supply 60 kHz (60 kHz + harmonics) (120 kHz, 180 kHz, etc.) 10 MHz + harmonics (20 MHz, 30 MHz, 40 MHz, etc.)

Processor 33 MHz

Display Driver 10 MHz

25

Wire to Wire Coupling Magnetic Fields Conducted Emission Source

To 28 VDC

Current

Conducted RF emissions may couple from source wires to adjacent wires

To Structure

26


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EMC IVT Visuals

Wire to Wire Coupling, cont. X

Factors affecting coupling between wires: z

Spacing between wires closer spacing means more coupling

z

Frequency content of signals higher frequencies mean more coupling

z

Length that wires are routed together longer length means more coupling

z

Proximity of circuit return wires closer return wires mean less coupling 27

Radiated Interference X

X

X

RF emissions from electrical or electronic equipment radiated directly from equipment or from connected signal or power wires Susceptibility can occur on other electrical or electronic equipment receiving the emissions through radio antennas, or on interconnecting wires acting as antennas Interference path is through air 28


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EMC IVT Visuals

Radiated Emission Sources Radiated emissions from LRU enclosure and wires at 10 MHz + harmonics, 33 MHz + harmonics 33 MHz + harmonics (66 MHz, 99 MHz, 132 MHz, etc.)

28 VDC Data bus, Discrete logic, Control signals, Analog signals

Switched-Mode Power Supply 60 kHz (60 kHz + harmonics) (120 kHz, 180 kHz, etc.) 10 MHz + harmonics (20 MHz, 30 MHz, 40 MHz, etc.)

Processor 33 MHz

Display Driver 10 MHz

29

Radiated Emission Coupling to Wires Radiated Fields

RF Emissions from LRU case

RF emissions on wires Emission Source

To Structure

To 28 VDC

30


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EMC IVT Visuals

RF Emissions Received By Antennas Very High Frequency(VHF) Communication Antenna Emissions radiated by avionics systems can radiate to aircraft antennas through:

RF emissions from avionic system

Windows Cargo and passenger door seams Hatches

31

VHF Communication Radio Example X

X

VHF communication radio operates from 117.975 to 137 MHz VHF receiver sensitivity z

z

z

RTCA DO-186A requires at least 10 microvolt sensitivity Actual signals that break squelch can be 1 to 2 microvolts Detectable tones on an active channel may be around 0.5 microvolts 32


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EMC IVT Visuals

DO-160 Emissions for VHF Frequencies X

X

RTCA/DO-160 Section 21 defines categories for RF emissions in VHF comm bands z

Cat B allows ~ 2000 microvolts per meter

z

Cat L allows ~ 200 microvolts per meter

38 to 53 dB minimum path loss between system in transport airplane cabin and VHF receiver (from RTCA/DO-233)

33

VHF Communication Interference Results X

X

Aircraft system can have emissions received by VHF z

Section 21 Cat B — 4.5 to 25 microvolts

z

Section 21 Cat L — 0.5 to 2.5 microvolts

Compare this with receiver sensitivity that ranges from 0.5 to 2 microvolts!

34


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EMC IVT Visuals

Methods for Limiting Radio Interference X

Methods include: z

Decreasing radio receiver sensitivity (reduces communication range)

z

z

Increasing separation distance from interference source to radio antenna Reducing level of RF emissions from interference source (preferred method)

35

Pulses and Spectrum X

X

X

Rise time and fall time of pulses determine spectral power Shorter rise (and fall) times produce higher frequency content Not just frequency of fundamental signal, but also rise time of signal

36


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EMC IVT Visuals

Pulse Waveform Current (A)

1 0.8 0.6 0.4 0.2 0 -10

0

10

20

30

40

50

Time (microseconds)

60

70

37

Pulse Spectrum Amplitude (A/Hz)

1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 1.00E-09 1.00E-10 1.00E+02

1.00E+04

1.00E+06

1.00E+08

Frequency (Hz) 38


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EMC IVT Visuals

Example - Inductive Switching Transients Magnetic Fields Switch

Relay Coil

Current

To 28 VDC

To Structure

39

Electromagnetic Transients X

Fast transients ⇔ high frequency content

⇔ Time →

Frequency → 40


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EMC IVT Visuals

Transient Generation X

Sources of electromagnetic transients and pulses z

Switching inductive loads

z

Electrostatic discharges

z

Power bus switching

z

Lightning

41

Precipitation Static (P-Static) Interference

42


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EMC IVT Visuals

Precipitation Static Interference +

-- -

-- -- - -

+

+ X

Result of highvoltage aircraft charging from snow, ice, rain and dust

X

Effects include: Radio noise z Visible corona (St. Elmo’s fire) z Puncture through insulating materials (radomes & windows) z

43

What is P-Static? X

Impact of particles separates electrical charge from particles, so aircraft acquires charge z

z

z

High-voltage corona discharge from aircraft extremities High-voltage flashover across insulating structure Arcs between isolated metal panels 44


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EMC IVT Visuals

Controlling P-Static Interference X

X

Static dischargers (wicks) z

Discharge lower voltage than natural corona

z

Reduce radio noise

Resistive paints on non-conducting surfaces, such as fiberglass fairings

X

Electrical bonding metal structure & panels

X

Rounding sharp corners of antennas 45


December, 2002


Part 2: Approaches for EMC

EMC IVT Visuals


Aircraft Electromagnetic Compatibility Part 2

46

Course Contents - Part 2a X

Approaches for Electromagnetic Compatibility z

Equipment circuit design

z

System installation design

z

Aircraft arrangement and structure design

z

Bonding and grounding

47


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EMC IVT Visuals

Course Contents - Part 2b X

Aircraft EMC Regulatory Requirements z

Aircraft electromagnetic environment effects requirements

z

System and equipment requirements

z

Portable electronic devices

48

Approaches for Electromagnetic Compatibility

49


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EMC IVT Visuals

Controlling EMI X

Limit EMI sources z

X

Circuit design, filter, change operating frequencies

Physically separate EMI source & victim z

z

Move source farther from victim - generally only effective for radiated interference Revise wiring layout, with separation between source and victim wiring 50

Controlling EMI, cont. X

Electromagnetically separate EMI source and victim z

z

X

Add shielding to source, source wiring, victim wiring Add in-line filters and suppression

Protect (harden) EMI victim z z

Circuit design, filters, wiring layout Change operating frequencies 51


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EMC IVT Visuals

Shielding X

Can be applied to: z z z z z

X

Circuit components Wires Wire bundles LRU cases Structure

For EMI, shielding normally applied to LRU cases and wiring 52

Shielding Concepts X

Factors influencing shielding effectiveness depend on frequencies you intend to shield z

Quality of shield material (optical coverage, resistance)

z

X

Quality of shield terminations, splices and joints (resistance and inductance)

Shield terminations as important as shield material itself 53


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EMC IVT Visuals

Shielding Concepts, cont. X

Beware of data showing shielding effectiveness of shield material alone or claims of shielding greater than 40 dB z

Claims probably haven’t considered shield terminations

54

Shielded Wires

Effective shield terminated at both ends X

Ineffective shield - not terminated at both ends

Shields over wires must be terminated with low resistance and inductance at all connectors z

Except for some specific cases on audio wiring

55


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EMC IVT Visuals

Electrical Bonding and Grounding Ground Strap or Bonding Jumper

Bonding jumpers and ground straps may be used to control electromagnetic interference

56

Electrical Bonding X

X

Electrical bonding provides a controlled current path between equipment and aircraft structure Electrical bonding may be required for: z

System performance

z

Electrical fault protection

z

Electromagnetic compatibility

57


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EMC IVT Visuals

Bonding Effectiveness X

X X

For electromagnetic compatibility, bonding jumpers must have: z

Low resistance

z

Low inductance

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

58


December, 2002


Part 2: Aircraft EMC Regulatory Requirements

EMC IVT Visuals


Aircraft EMC Regulatory Requirements

59

Aircraft EMC Regulatory Requirements The words electromagnetic compatibility are NOT written in the regulations

60


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EMC IVT Visuals

14 CFR Part 23 X

X

23.1301 Function and Installation. Each item of installed equipment must . . . (d) Function properly when installed. 23.1309 Equipment, systems and installation. (a) Each item of equipment, each system, and each installation: (1) When performing its intended function, may not adversely affect the response, operation, or accuracy of any (i) Equipment essential to safe operation; . . . 61

14 CFR Part 23, cont. X

23.1431 Electronic Equipment. (b) Radio and electronic equipment, controls, and wiring must be installed so that operation of any unit or system of units will not adversely affect the simultaneous operation of any other radio or electronic unit, or system of units, required by this chapter.

62


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EMC IVT Visuals

AC 23-8A Flight Test Guide for Part 23 Airplanes X

Chapter 5. Equipment z

z

Provides general EMC flight test guidance for airplane navigation and radio systems Specifies HF radio interference tests at 1 MHz intervals

63

AC 23-15 Small Airplane Certification Compliance X

4.v. Avionics Installation z

Mentions interference tests, but not specifically EMC

64


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EMC IVT Visuals

14 CFR Part 25 X

X

25.1301 Function and Installation. Each item of installed equipment must . . . (d) Function properly when installed. 25.1309 Equipment, systems and installation. (a) The equipment, systems, and installations whose functioning is required by this subchapter, must be designed to ensure that they perform their intended functions under any foreseeable operating condition. 65


25.1353 Electrical equipment and installations. (a) Electrical equipment, controls, and wiring must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other electrical unit or system essential to the safe operation.

66


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EMC IVT Visuals


25.1431 Electronic equipment. (c) Radio and electronic equipment, controls, and wiring must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other radio or electronic unit, or system of units, required by this chapter.

67

AC 25-7 Flight Test Guide for Transport Airplanes X

Chapter 6. Equipment z

Provides general EMC flight test guidance for airplane navigation and radio systems

68


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EMC IVT Visuals

AC 25-10 Miscellaneous NonRequired Electrical Equipment X X

X

5.f. Calls out RTCA DO-160 Section 21 tests 5.m(4) Describes interference effects. For airplane ground tests, operate communication and navigation equipment at low, high, and mid-band frequencies. States that ground EMI tests adequate for follow-on approvals for like or identical equipment types

69

Flight Test Requirements for Passenger Entertainment Systems X

ANM-100 Policy Memo 2/25/92 z

z

Flight and ground tests may be required for initial installation Ground tests are adequate for follow-on approvals

70


December, 2002



EMC IVT Visuals

14 CFR Part 27 X

X

27.1301 Function and Installation. Each item of installed equipment must . . . (d) Function properly when installed. 27.1309 Equipment, systems and installation. (a) The equipment, systems, and installations whose functioning is required by this subchapter must be designed and installed to ensure they perform their intended functions under any foreseeable operating condition. 71

14 CFR Part 29 X

X

29.1301 Function and Installation. Each item of installed equipment must . . . (d) Function properly when installed. 29.1309 Equipment, systems and installation. (a) The equipment, systems, and installations whose functioning is required by this subchapter must be designed and installed to ensure they perform their intended functions under any foreseeable operating condition. 72


December, 2002



EMC IVT Visuals


29.1353 Electrical equipment and installations. (a) Electrical equipment, controls, and wiring must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other electrical unit or system essential to safe operation.

73


29.1431 Electronic equipment. (b) Radio communication and navigation equipment, controls, and wiring must be installed so that operation of any one unit or system of units will not adversely affect the simultaneous operation of any other radio or electronic unit, or system of units, required by this chapter.

74


December, 2002



EMC IVT Visuals

14 CFR Part 29 ACs X

AC 29-2 Certification of Transport Category Rotorcraft z

AC 29.1353 Electrical Equipment and Installations –

z z

Recommends RTCA DO-160

AC 29.1431 Electronic Equipment AC 29 MG1 Certification Procedure for Rotorcraft Avionics Equipment –

Mentions EMC flight tests 75

EMC Testing for Rotorcraft with Electronic Engine Controls X Rotorcraft z

z

z

Policy No. ASW-2001-001

Focuses on non-required equipment installed on rotorcraft with critical electronic controls, such as FADEC Ground and flight EMC tests required for initial approval Revises guidance in AC 29-2C Miscellaneous Guidance (MG) 4 and AC 27-1B MG4

76


December, 2002



EMC IVT Visuals

AC 43.13-1B Aircraft Inspection and Repair X Chapter z z

11 Aircraft Electrical Systems

Section 15. Grounding and Bonding Section 8. Wiring Installation Inspection Requirements – –

–

11-106 Electromagnetic Interference 11-107 Interference Tests - Operate communication and navigation systems at low, high and mid-band frequencies Ground EMC tests OK for follow-on approvals 77

14 CFR Part 91 Portable Electronic Devices X

Sec. 91.21 Portable electronic devices. (a) . . . no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device . . . (b) Paragraph (a) does not apply to . . . (5) Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.

78


December, 2002


Part 3: Aircraft EMC Verification

EMC IVT Visuals


Aircraft Electromagnetic Compatibility Part 3

79


Aircraft EMC Verification z

Aircraft tests

z

System and equipment qualification

X

EMC Examples

X

Wrap-Up

X

References

80


December, 2002



EMC IVT Visuals

Aircraft EMC Verification

81

EMC Verification Approaches X

Equipment qualification

X

Operational aircraft functional checks

X

Aircraft radio checks

X

Radio interference measurements

82


December, 2002



EMC IVT Visuals

Equipment Qualification Equipment laboratory tests, such as RTCA/DO-160 X Advantages z z

z

X Disadvantages

Equipment tests in lab. Standardized test procedures and categories Confident equipment will have satisfactory EMC on aircraft

z

z

z

No guarantee of EMC on aircraft Considers EM emissions from 1 item of equipment, not entire system Does not consider susceptibility of other aircraft systems

83

Equipment Qualification Standards X

X

RTCA/DO-160 or EUROCAE/ED-14 (these are equivalent) Equivalent industry standards (for example, Boeing D6-16050-4C)

X

TSO-specific requirements

X

MIL-STD-461

84


December, 2002



EMC IVT Visuals

RTCA/DO-160 EMC Requirements X

RF Emissions - Section 21 z

X

RF Susceptibility - Section 20 z

X

Installed equipment should meet this or equivalent May include high level HIRF tests

Audio and Induced Signal Susceptibility - Sections 18 and 19 85

RTCA/DO-160 Section 21 X

X

Measures RF emissions z

Conducted on signal and power wires

z

Radiated from LRU and wires

Four emissions categories (B, L, M & H) z

Category B limits allow 10 times higher emissions than other categories

86


December, 2002



EMC IVT Visuals

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

RF Emission (dBµv/m)

100.0 90.0 80.0 70.0

Category B

60.0 50.0

Category L

40.0 30.0 20.0

1

10

100

1,000

10,000

Frequency (MHz) 87

RF Emission (dBµv/m)

RTCA/DO-160D Section 21 Category M Radiated 100.0 90.0 80.0 70.0 60.0 50.0 40.0

Category M

30.0 20.0 1

10

100

Frequency (MHz)

1,000

10,000

88


December, 2002



EMC IVT Visuals

RTCA/DO-160D Section 21 Category H Radiated RF Emission (dBµv/m)

100.0 90.0 80.0 70.0 60.0 50.0

Category H

40.0 30.0 20.0 1

10

100

1,000

10,000

Frequency (MHz) 89

RTCA/DO-160D Section 21 Categories B, L, M, & H Conducted RF Emission (dBµv/m)

100.0 90.0 80.0 70.0

Category B Interconnecting Wires

60.0

Category B Power Wires Categories L, M, & H

50.0 40.0

Interconnecting Wires

30.0 20.0 10.0 0.0 0.1

Categories L, M, & H Power Wires 1

10

100

Frequency (MHz) 90


December, 2002



EMC IVT Visuals

Measured RF Conducted Emissions Category M 150 kHz to 100 MHz

91

Measured RF Radiated Emissions Category M Vertical Antenna Polarization 25 to 200 MHz

92


December, 2002



EMC IVT Visuals

What about FCC 47 CFR 15? X

X

X

X

Most consumer electronics meet FCC Class B requirements in 47 CFR 15 Test setup and procedures are different than DO-160 Section 21 Uses open air test site instead of shielded room Emission limits are similar to DO-160 Section 21 Category L 93

Field Strength (dBµv/m)

FCC and RTCA/DO-160 Emission Limit Comparison 80 70

DO-160 Cat B

60 50

FCC Part 15 Class B

40 30

DO-160 Cat L

20 10 0 10

DO-160 levels adjusted for 3 meters separation between antenna and equipment under test 100

Frequency (MHz)

1,000

94


December, 2002



EMC IVT Visuals

Other Sections X

Audio susceptibility - Sections 18 & 19 z

X

Determines if equipment can withstand power and audio frequency conducted interference

Inductive switching transients - Section 19 z

Determines if equipment can withstand transients typical during inductive load switching 95

Inductive Switching Transient

200 v

20µs

96


December, 2002



EMC IVT Visuals

Operation Aircraft Functional Checks Typically uses a source-victim matrix X Disadvantages

X Advantages z

z

z

Uses real aircraft operating conditions Most conditions may be performed during ground test No special-purpose RF measurement equipment required

z

z

z

Thorough source-victim testing time-consuming Acceptance criteria more difficult to define Special test equipment required to make some systems function on ground

97

Aircraft Radio Checks Aircraft radio receivers can be tuned across channels to detect interference X Disadvantages

X Advantages z

z

No special equipment required May be performed during ground test

z

z

z

Lengthy process to tune each channel Selected channel tuning will miss narrow-band interference Acceptance criteria must be defined 98


December, 2002



EMC IVT Visuals

Radio Channels - Examples X

X

VHF comm 25 kHz spacing 760 channels VHF comm 8.33 kHz spacing 2280 channels

X

Localizer - 40 channels

X

Glide slope - 40 channels

99

Acceptance Considerations X

VHF comm z z

X

No unintended squelch breaks No audio tones that interfere with communications

Localizer, glide slope, and VOR z

No guidance errors

z

No audio tones to interfere with station ID

100


December, 2002



EMC IVT Visuals

Radio Interference Measurements Interfering signals can be measured at aircraft radio receiver antenna connectors X Disadvantages

X Advantages z

z

z

Provides quantitative measurement of interfering signals

z

Perform during ground test May use with radio tuning test

z z z

Ambient signals mask interfering signals at specific test site Define acceptance criteria Special test equipment Applies only to radio interference

101


December, 2002


Part 3: Aircraft EMC Examples

EMC IVT Visuals


Aircraft EMC Examples

102

Example 1 X

Transport Airplane Localizer Interference

103


December, 2002



EMC IVT Visuals

Transport Airplane Localizer Interference X

X

During Category 1 autoland airplane diverged left of runway center line No autoland warning annunciated

104

Airplane Localizer Antenna Signal dB(uV)

RF Interference Measured at Localizer Receiver 20 15

Airport Localizer Signal

10 5 0 -5

-10 1.08E+08

1.10E+08

1.12E+08

1.14E+08

1.16E+08

1.18E+08

Frequency (Hz)

105


December, 2002



EMC IVT Visuals

Current Measured on Control Panel Wire Bundle Control Panel Wire Bundle Current dB( µA)

20 15 10 5 0 -5 -10 -15 -20 -25 1.08E+08

1.10E+08

1.12E+08

1.14E+08

1.16E+08

1.18E+08

Frequency (Hz)

106

System Configuration X

X

X

Airplane had autopilot with mode control panel Mode control panel wire bundles routed adjacent to weather radar wire bundles Weather radar wire bundles routed through nose bulkhead to weather radar, where localizer antennas installed

107


December, 2002



EMC IVT Visuals

System Configuration, cont.

Mode Control Panel

Localizer Antenna 108

Why Did This Happen? X

X

X

X

Mode control panel generated RF conducted emissions from internal processor clock RF conducted currents coupled to adjacent localizer coax cable Localizer coax cable conducted RF conducted emissions to the airplane localizer antennas Localizer receiver detected emissions as a valid localizer signal

109


December, 2002



EMC IVT Visuals

Example 2 X

Small Airplane Flap Control Interference

110

Small Airplane Flap Control X

Electronic flap position controller malfunctioned during VHF comm radio use z

During flap actuation, flaps would stop at uncommanded positions or reverse if pilot transmitted on VHF comm radio

111


December, 2002



EMC IVT Visuals

112

System Configuration X

X

X

X

Flap drive, controller and wiring installed below rear seats VHF comm antenna installed on bottom centerline of airplane, just below flap drive Flap controller wiring to flap drive uses unshielded wires Airframe primarily fiberglass, with aluminum foil for shielding & grounding 113


December, 2002



EMC IVT Visuals

System Description X

X

X

Flap actuator used electrical motordriven jackscrew Flaps have three positions: stowed, mid-extension, and full extension Magnetic proximity sensor used to detect position of jackscrew

114

System Description, cont. X

X

Electronic flap controller used pilot flap switch and magnetic sensors to command jackscrew motor Electronic flap controller used TTL circuit logic to control and command flap position

115


December, 2002



EMC IVT Visuals

System Schematic Cockpit Flap Position Switch

Electronic Flap Controller

Magnetic Jackscrew Position Sensor Flap Actuator Motor

VHF Comm Transceiver

VHF Comm Antenna 116

Why Did This Happen? X VHF

comm transmitter induced RF current on flap control wires

X RF

current was conducted into flap controller and was rectified by TTL circuit elements

X Rectified

RF currents were interpreted as a logic change by the TTL circuit elements

X Flap

controller was not test for RF susceptibility

117


December, 2002



EMC IVT Visuals

Changes Required X

X

Simultaneous flap operation and comm transmission prohibited Service bulletin created to add EMI suppression to flap system wiring z

Ferrite cores added to flap control wiring

118

Example 3 X

Helicopter Audio Interference

119


December, 2002



EMC IVT Visuals

Helicopter Audio Interference X

X

Medical evacuation helicopter crashed following loss of engine power Electromagnetic interference to fullauthority digital engine control (FADEC) was suspected

120

121


December, 2002



EMC IVT Visuals

Facts X X

X

X

X

Medevac operation in cruise flight Pilot heard a sharp, increasing pitch tone in his headset Pilot placed FADEC switch to MANUAL position Engine experienced several excursions of shutdown and re-ignitions Helicopter autorotated to hard landing 122

Helicopter Configuration X

X

X

Single engine helicopter with single channel FADEC Medical equipment, additional radios, and cell phone installed Radios and cell phone connected to helicopter interphone system

123


December, 2002



EMC IVT Visuals

Cell Phone Configuration Helicopter audio interphone system

Pilot’s headset

Cell phone base Cell phone voltage converter

Helicopter to cell phone voltage converter

Helicopter power

124

Why Did This Happen? X

X

X

Cell phone voltage converter installed under cabin floor Corrosion on voltage converter circuit card resulted in voltage converter audio oscillation Audio oscillation conducted on power wires to cell phone base 125


December, 2002



EMC IVT Visuals

Impact of Audio Interference X

X

X X

Audio oscillation coupled to interphone, resulted in audio tone on pilot’s headset Pilot apparently interpreted audio tone as FADEC FAIL warning Pilot selected FADEC MANUAL mode Rotor RPM exceeded limits, resulting in automatic engine shutdown 126

Implications X

X

Non-essential, non-required systems can have impact on required systems Even nuisance audio EMI can result in unsafe conditions

127


December, 2002


Part 3: EMC IVT Wrap-Up

EMC IVT Visuals

Part 3: EMC IVT Wrap-Up

EMC IVT Wrap-Up X

Focused on electromagnetic compatibility, not lightning and HIRF

X

EMC fundamentals review

X

Regulatory basis for EMC

X

Approaches to compliance

X

Examples

128


December, 2002


EMC IVT Quiz

Appendix B

Appendix B Aircraft Electromagnetic Compatibility Quiz


December, 2002

Aircraft Electromagnetic Compatibility Appendix B-1

EMC IVT Quiz

Appendix B

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 receiver interference? 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.


December, 2002


EMC IVT Quiz 5.

Appendix B

Common sources of RF emissions within avionics equipment are: a. Computer clocks b. RF oscillators. c. Switching power supplies. d. All of these.

6.

RF emissions that couple from one wire bundle to an adjacent wire bundle can 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 other systems 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 electromagnetic compatibility? a. 25.1301. b. 25.1309. c. 25.1353. d. None.


December, 2002


EMC IVT Quiz 9.

Appendix B

Which sections of RTCA/DO-160 have test procedures and limits for radio frequency 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.


December, 2002


Evaluation

Appendix C

Appendix C Course Evaluation Form If you are taking this course via IVT/ATN and you are logged on to a keypad, you will be asked to complete the course evaluation by using the Viewer Response System keypad. Your instructor will provide directions on how and when to complete the course evaluation. There are also some open-ended questions that you can respond to (in writing), and these can be faxed back to the ATN studio. If you are completing the course via self-study video, please complete the form and return to your Air Training Manager (ATM). Please note that to get credit in your training history for watching the video, you MUST return the evaluation form.


December, 2002

Aircraft Electromagnetic Compatibility Appendix C-1

Evaluation

Appendix C

IVT or Self-Study Video Evaluation Form Aircraft Electromagnetic Compatibility IVT Course # 62835; Video/Self-study # 25835 December, 2002 We want your candid opinion on the course you just completed. Your feedback will help us to provide the best possible products and services. Please respond to the questions below. If you have completed via IVT, your instructor will prompt you when to enter your answers in your keypad. If you have completed the video option, complete this form manually and return to your ATM. You must complete and return this evaluation form to your ATM in order to get credit for the video self-study option.

A = Highly Satisfactory

B = Satisfactory

C = Somewhat Satisfactory

D = 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


December, 2002


Evaluation

Appendix C

Aircraft Electromagnetic Compatibility IVT 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, please fax this sheet to the ATN studio at  405 954-0317. If completing the previous page and this one after watching the video, send to your AIR Training Manager (ATM) to get credit in your training history. IVT Course Federal Aviation Administration

December, 2002


Aircraft Electromagnetic Compatibility

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