Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 and 747-400F series airplanes. This proposed AD was prompted by reports of cracking in the outboard flange of the longeron extension fittings, which attach to the wing-to- body fairing support frame. This proposed AD would require repetitive inspections of the longeron extension fittings for cracking, and corrective actions if necessary. We are proposing this AD to detect and correct cracks in the longeron extension fittings, which can become large and adversely affect the structural integrity of the airplane.