AD FAA-2014-1027

The FAA proposes to amend certain airworthiness regulations for transport category airplanes regarding lightning protection of fuel tanks and systems. This action would establish design requirements for both normal conditions and possible failures of fuel tank structure and systems that could lead to fuel tank explosions, add new maintenance requirements related to lightning protection features, and impose specific requirements for airworthiness limitations in the instructions for continued airworthiness. We would create performance-based standards for prevention of catastrophic fuel vapor ignition caused by lightning by regulating the risk due to both ignition sources and fuel tank flammability. This change would allow designers to take advantage of flammability reduction technologies whose effectiveness was not foreseen when earlier revisions to these rules were written. This change would also relieve some of the administrative burdens created by the current regulations. These proposed amendments are based on recommendations from the Large Airplane Fuel System Lightning Protection Aviation Rulemaking Committee (Lightning ARC).