Airworthiness Directives; Boeing Model 777-200 and -300 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to all Boeing Model 777-200 and -300 series airplanes. This action requires revising the Limitations Section of the Airplane Flight Manual to prohibit the dispatch of certain airplanes under certain conditions. This amendment also requires repetitive inspections to ensure correct operation of the backup generators; and, for certain airplanes, a one-time inspection to detect damage of the engine external gearbox; and corrective actions, if necessary. This amendment is prompted by reports of inflight shutdowns due to sheared backup generator shafts. The actions specified in this AD are intended to prohibit the dispatch of an airplane with an engine-mounted backup generator having a sheared shaft; and to detect and correct damage to the engine, which could result in inflight shutdowns.