Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes. This AD was prompted by reports of unreliable performance of the water and fuel scavenge system; failure of the fuel scavenge function can cause trapped fuel, resulting in unavailable fuel reserves. This AD requires incorporating operating limitations; or modifying the water and fuel scavenge systems in the fuel tanks, modifying the fuel jettison system, making electrical changes in the main equipment center, modifying the wiring in certain panels, and installing new software. We are issuing this AD to address the unsafe condition on these products.