Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777 airplanes. This AD was prompted by reports of unreliable performance of the fuel scavenge system. This AD requires changing the main fuel tank water scavenge system, center fuel tank fuel scavenge system, and certain electrical panels; doing related investigative actions; doing corrective actions if necessary; and, for certain airplanes, changing the fuel scavenge system to give redundant control of the center override/jettison fuel pumps and main jettison fuel pumps. We are issuing this AD to prevent fuel exhaustion and subsequent power loss of all engines due to loss of capability to scavenge fuel in the center fuel tank.