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• August 14, 2016 Create Date
• August 14, 2016 Last Updated

Lightning Direct Effects Handbook

This handbook is intended to assist aircraft design and certification engineers in
protecting small personal aircraft against the direct effects of lightning strikes. It is also
intended to assist Federal Aviation Administration (FAA) certifying engineers in assessing the
adequacy of proposed lightning protection designs. Emphasis has been given to successful
test results (which have largely been condensed) in an effort to assist protection design of new
aircraft through similarity to previous successful designs. This compilation of data should also
allow a designer to make early decisions and minimize development testing. The design
engineer will also find this handbook a means of avoiding either ineffective protection methods
or the testing of previously proven techniques.

This handbook addresses the direct effects of lightning strikes. Its intent is to provide
guidance and educate engineering personnel responsible for lightning protection of primary
aircraft structure. The recommendations included in this document are specific to the design of
small personal aircraft and may not be as applicable to large composite aircraft designs. It is
intended to assist engineers with limited experience in the design of aircraft lightning strike
protection. Information is included on the natural lightning environment, the interaction between
aircraft and lightning, and the mechanism of the lightning strike effects on the aircraft.

Protection design guidelines in this handbook are applicable to composite airframes,
(including primary and secondary structures), control surfaces, exterior skins and fuel tanks.
Composite materials to be included are fiberglass, aramid fiber and carbon fiber reinforced
epoxies. Boron structures are addressed only briefly, as this material is not in wide use. This
handbook also includes a discussion of verification procedures for determining the adequacy of
protection designs.

Included herein is design and test data accumulated from a variety of references. These
include airframe manufacturers and U.S. government research and development agencies.
Specific sources are referenced throughout the handbook.

This handbook will not address the protection of: a) electrical systems and components
and avionics, b) fuel system and fuel system components other than tanks, c) flight control
systems other than control surfaces and d) protection of personnel from electrical shock. These
items usually are exposed to lightning indirect effects and require case-by-case treatment. The
protection of metal skins and structures is treated only briefly since other sources of lightning
protection design information for metal airframes are readily available.