Electromagnetic Compatibility

The often misunderstood source of system anomalies.

Throughout my flight test career, when asked to troubleshoot flight test events like a rudder kick in a turn, pressurization bump in descent, indicator lights flickering, or noise on a communication radio, the investigation resulted with a common thread through all these situations, electromagnetic interference or EMI. 

There many famous examples of electromagnetic interference, ranging from nuisances to catastrophic failures with loss of life. One of the earliest tragic accidents occurred in 1967 onboard the US aircraft carrier Forrestal, which was deployed off the coast of North Vietnam. An uncommanded missile launch from one of the aircraft parked on the flight deck, causing an explosion and fire from the erupting fuel tanks. 134 servicemen died in the accident which was thought to be caused by the ship’s high-powered radars generating a high voltage within the missiles fire control system.

Another serious example was the series of fatal accidents of the UH-60 Black Hawk helicopter started in 1982 that killed a total of 22 servicemen. Investigations discovered that the electronic flight control system was susceptible to the radio frequency energy when flying near high powered radio transmitters. 

All these occurrences required extensive investigation, ground and flight testing and airplane wiring modifications to find and correct the interference.

Course curriculum

    1. Copy of Before we begin... a pre-course survey.

    2. Introduction to EMI-EMC: Why did that APU shutdown?

    1. What does EMI look like?

    2. Regulatory Guidance History

    3. Aircraft Electromagnetic Environment

    4. A Plan for Electromagnetic Compatibility

    1. Antennas

    2. Frequency Spectrum

    3. Time vs. Frequency Domain

    4. Decibels

    1. RF Emissions

    2. Electromagnetic Transients

    3. High Intensity Radiated Fields (HIRF)

    4. Precipitation Static

    5. Cellular

    1. Lab Testing

    2. Airplane EMC Ground Testing

    3. Aircraft Source/Victim Ground Test

    4. Non-Instrumented Radio Ground Test

    5. Instrumented Radio Ground Test

    6. EMC Flight Testing

    7. Acceptance Criteria and Compliance Finding

    8. Starlink Installations Example

    1. Conclusions

    2. References

About this course

  • $299.00
  • 25 lessons

Instructo

Instructor Flight Test Engineer Dan Hrehov

Dan Hrehov has over thirty-five years of flight test experience in the Seattle area and has worked on most avionics systems on Boeing Commercial Model types from the 727 to the 787. His primary work has been flight testing avionics, automatic flight controls systems, navigational and communication radios, flight management computers and certification for electromagnetic compatibility. Dan is a Professional Engineer and a SFTE Fellow, who has published several papers and conducted many symposium workshops on the subjects of FMC testing, Lightning, EMC, Data Systems Certification, and Safety of Instrumentation Installations.