FAA FAA-RD-73-99 PDF

The increasing number of single and multi-engine general aviation aircraft, and their more common use of sophisticated avionics, is resulting in more frequent operation of these aircraft under instrument flight rule (IFR) conditions. Along with this trend is another one toward greater application of non-metallic materials in aircraft structural and fuel systems, and greater use of solid state components in avionics. This combination results in greater potential vulnerability to lightning strikes, and may require that specific lightning protective measures be developed and applied if operational reliability and flight safety are to be maintained. Protective measures suitable for all-metallic aircraft, for example, may not be adequate for aircraft with some fiberglas or plastic sections. The all-metallic airframe is, in many ways, quite compatible with basic lightning protection requirements, and often only minor design modifications have been needed to provide adequate lightning protection. The same may not be true of all new aircraft designs, however.