Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 series airplanes. This proposed AD was prompted by a report of a certain modification that causes interference with inspections that are intended to detect fatigue cracks. This proposed AD would require repetitive low frequency eddy current (LFEC) inspections of a certain fuselage upper skin lap splice for cracks, repetitive high frequency eddy current (HFEC) inspections of a certain fuselage upper skin lap splice for cracks, and applicable on-condition actions. The FAA is proposing this AD to address the unsafe condition on these products.