This ED provides detailed information, guidance and methods in support of the Federal Aviation Administration (FAA) Advisory Circular (AC) 20-136. AC 20-136 provides a means, but not the only means, for demonstrating compliance with Title 14 of the Code of Federal Regulations (14 CFR) 23.1306 (Amendment 23-61), 23.2515 (Amendment 23-64), 25.1316, 27.1316 and 29.1316. It is also intended for this ED to provide the same information, guidance and methods, to the European Aviation Safety Agency (EASA) certification specifications CS 23.1306 (Amendment 23/4), 23.2515 (Amendment 23/5), 25.1316, 27.1316, and 29.1316, and associated Acceptable Means of Compliance (AMC) 20-136. This ED provides references relevant to identifying: (1) acceptance criteria for the indirect effects of lightning compliance approaches, (2) verification (analysis and test) methods including those associated with multiple stroke and multiple burst, (3) recommended design options to optimize needed system immunity to lightning indirect effects and (4) provide guidance in the areas of continued airworthiness of the lightning protection. Equipment hazards due to the indirect effects on equipment mounted on the aircraft exterior, equipment located within the aircraft interior as well as all associated interconnecting wiring are addressed. This ED provides additional guidelines in the application of indirect effects of lightning tests identified in ED-14/DO-160 Section 22. The FAA and EASA regulations apply to all adverse effects of lightning for electrical and electronic systems. Refer to EUROCAE ED-113/SAE ARP5577 for guidance related to lightning direct effects on electrical and electronic systems.

PURPOSE

This ED expands on the topics discussed in AC 20-136/AMC 20-136. Guidelines are provided which explain the approaches to compliance with the FAA regulations and the EASA certification specifications. Discussions are applicable to all categories of airplanes and rotorcraft. This ED is not intended to provide mandatory approaches to compliance. In many cases, the path to compliance may use one or more of several methods. Applicants may elect to demonstrate compliance through alternative methods that are acceptable to their certifying airworthiness authority.