AMC1 27.610 Lightning and static electricity protection

• ED Decision 2023/001/R found in: CS-27 Amdt 10 - Small Rotorcraft (Feb 2023)

AMC1 27.610 Lightning and static electricity protection ED Decision 2023/001/R (a) Purpose This AMC provides an acceptable means of compliance for evaluation of rotorcraft components after lightning strike. (b) Related Certification Specifications [CS 27.610](#_DxCrossRefBm8893896) ‘Lightning and static electricity protection’ [CS 27.571](#_DxCrossRefBm8893884) ‘Fatigue evaluation of flight structure’ [CS 27.573](#_DxCrossRefBm8893887) ‘Damage tolerance and fatigue evaluation of composite structures’ [CS 27.1529](#_DxCrossRefBm8893888) ‘Instructions for Continued Airworthiness’ (c) Explanation [CS 27.610](#_DxCrossRefBm8893896) requires the protection of rotorcraft structural components, propulsion system, gearboxes, mechanical and hydraulic control systems from lightning effects that could result in catastrophic failures. However, damage, failure or departure of any rotorcraft component which could endanger the rotorcraft or its occupants should be part of the evaluation. This AMC provides detailed guidance on damage tolerance evaluation, including residual strength criteria after lightning strike to ensure continuous safe flight and landing. Each part, the failure of which implies potential catastrophic consequences and that is exposed to damage under lightning conditions, should be subject to further evaluation which includes: (1) the nature and extent of the lightning damage (threat assessment, damage detectability, etc.); (2) the demonstration of the functionality of the affected part up to detection; (3) a static residual strength capability demonstration supported by analysis and/or test; (4) when found necessary, a fatigue evaluation of a part with lightning damage for the demonstration of the exposure time before detection. The airworthiness instruction requested after lightning strike (flight manual and maintenance instructions, etc.) should be consistent with the functional, static and fatigue evaluation of the damage consequences (considered to be a partial failure). A similar approach should be considered for non-metallic components (for composite, see the AMC 20-29 (11c) guidance). The above approach is also considered to be applicable for parts departure which could preclude continued safe flight and landing. For non-structural components (e.g. radomes, panels), only static residual strength is requested for part detachment which could preclude continued safe flight and landing. [Amdt 27/10]