Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777 airplanes. This proposed AD was prompted by reports of fire and smoke at the engine aft pylon area resulting from fuel leakage caused by a damaged O-ring in the fuel coupling attached to the wing front spar. This proposed AD would require applying sealant to fill the gap between the lower wing panels adjacent to the strut aft vapor barrier. We are proposing this AD to prevent fire and smoke at the engine aft pylon area in the event of a fuel leak, which could cause personal injury during ground operations. A fire spreading back and up to the aft fairing pylon can result in an uncontrolled fire in the strut and ignite the fuel tank.