Summary
We propose to adopt a new airworthiness directive (AD) for certain Model 777-200, -200LR, -300, and -300ER series airplanes. This proposed AD would require removing and repairing the sealant at the four lower corners of the wing center section and the four lower t- chord segment gaps on each side of the wing center section. This proposed AD results from reports of fuel leakage from the center tank. We are proposing this AD to detect and correct improperly applied sealant, which could result in the disbonding and displacing of sealant, and consequent fuel leaks. On the ground, uncontained fuel leakage could result in pooling, and pooling combined with an ignition source could result in a fire.