Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-8 and 747-8F series airplanes. This proposed AD was prompted by an analysis by the manufacturer, which revealed that certain fuse pins for the strut-to-wing attachment of the outboard aft upper spar are susceptible to migration in the event of a failed fuse pin through bolt. This proposed AD would require replacing the fuse pins for the strut-to-wing attachment of the outboard aft upper spar with new fuse pins, and replacing the access cover assemblies with new access cover assemblies. We are proposing this AD to prevent migration of these fuse pins, which could result in the complete disconnect and loss of the strut-to-wing attachment load path for the outboard aft upper spar. The complete loss of an outboard aft upper spar strut-to-wing attachment load path could result in divergent flutter in certain parts of the flight envelope, which could result in loss of control of the airplane.