Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 777 airplanes. This proposed AD was prompted by reports of latently failed fuel shutoff valves discovered during fuel filter replacement. This proposed AD would require revising the maintenance or inspection program to include a new airworthiness limitation. We are proposing this AD to detect and correct latent failures of the fuel shutoff valve to the engine, which could result in the inability to shut off fuel to the engine and, in case of certain engine fires, an uncontrollable fire that could lead to wing failure.