Transport Airplane Fuel Tank and System Lightning Protection

The FAA is amending certain airworthiness regulations for transport category airplanes regarding lightning protection of fuel systems. This action is relieving in several ways. It removes the requirement for manufacturers to provide triple-redundant fault tolerance in lightning protection. It removes regulatory inconsistency by establishing a single standard for lightning protection of both fuel tank structure and fuel tank systems. It establishes a performance- based standard that the design and installation of fuel systems prevent catastrophic fuel vapor ignition caused by lightning and its effects. This performance-based standard allows applicants to choose how to provide the required level of safety. This action requires airworthiness limitations to preclude the degradation of design features that prevent catastrophic fuel vapor ignition caused by lightning. Its intended effects are to align airworthiness standards with industry's and the FAA's understanding of lightning, and to address issues of inconsistency and impracticality that applicants experienced with previous lightning protection regulations.