Action
Notice of proposed rulemaking (NPRM).
Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all The Boeing Company Model 707 and Model 727 airplanes. This proposed AD was prompted by a report indicating cracking in fastener holes at the center wing box and at certain positions of the rear spar and lower skin on a Model 737-300 airplane. A cross model review determined that similar cracking of the fastener holes in the center wing box lower skin could occur on Model 707 and Model 727 airplanes. For Model 707 airplanes this proposed AD would require repetitive detailed inspections of the center wing box lower skin for cracking and repetitive high frequency eddy current (HFEC) and ultrasonic (UT) inspections of the rear spar lower chord at a certain position for cracking, repetitive sealant application, and repair if necessary. For Model 727 airplanes this proposed AD would require repetitive detailed inspections of the center wing box, lower skin, and rear spar lower chord at a certain location for cracking, repetitive sealant application, and repair if necessary. The FAA is proposing this AD to address the unsafe condition on these products.