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This document is intended to be a user’s manual to AC 25.954-1 on acceptable means of compliance for applicants with regards to § 25.954 at Amendment 25-146 and to encourage a consistent approach to be applied across industry. This document is also intended to be a user’s manual to AMC 25.954 on acceptable means of compliance for applicants with regards to EASA CS 25.954 at Amendment 26. The FAA Advisory Circular (AC) and the EASA Acceptable Means of Compliance (AMC) documents appear to provide equivalent guidance, using identical wording in most sections. Applicants should coordinate with their certifying authority to ensure that their proposed approach is acceptable, and the means of compliance and compliance data planned are sufficient for certification. It is recommended that the applicant verify that use of the guidance in this document is acceptable to their certifying authority.

The environment and test waveforms defined in this SAE Aerospace Recommended Practice (ARP) account for the best lightning data and analysis currently available. The quantified environment and levels herein represent the minimum currently required by certifying authorities, consistent with the approach applied in related lightning documents. Lightning, like other weather phenomenon, is probabilistic in nature. Levels and waveforms vary considerably from one flash to the next. Within this document, standardized voltage and current waveforms have been derived to represent the lightning environment external to an aircraft. These standardized waveforms are used to assess the effects of lightning on aircraft. The standardized external current waveforms have in turn been used to derive standardized transient voltage and current test waveforms that can be expected to appear on cable bundles and at equipment interfaces within an aircraft.