Chapter 27 - Electromagnetic Interference/Electromagnetic Compatibility

Ideally, Electromagnetic Interference/Electromagnetic Compatibility (EMI/EMC) testing should have been completed before an aircraft makes its initial flight. However, it is almost inevitable that problems will occur during the ensuing flight test program. Moreover, the Flight Test Engineer (FTE) will be involved in the ground testing of the aircraft. This Section provides some background information on EMI/EMC for the novice FTE involved in these disciplines. Furthermore, it identifies some of the standards and specifications used for developing test objectives and procedures for EMI testing. The discussions are based primarily on existing military requirements. This was done with the supposition that industrial and commercial specifications may vary from country to country, whereas the referenced military documents are uniformly related and generally obtainable. However, the one exception is a set of civil standards that are used all over the world. These standards are continually updated and thoroughly address the EMI conditions to which civil aircraft are subjected. [27-1] Further, this Section describes the major sources of EMI and the broad range of system-subsystem EMI/EMC testing, typical test equipment, and the facilities generally used. In addition, some basic EMI precautions to be taken in designing aircraft and instrumentation systems are discussed.