AD FAA-2015-0498

We are superseding Airworthiness Directive (AD) 2007-16-08, which applied to all The Boeing Company Model 747-100, 747-100B, 747- 100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes. AD 2007-16-08 required repetitive inspections for cracking of the station 800 frame assembly, and repair if necessary. This new AD continues to require repetitive inspections for cracking of the station 800 frame assembly, and repair if necessary, and expands the inspection area. This AD was prompted by reports of cracks found at the forward and aft inner chord strap and angles on the station 800 frame on the left-side and right-side main entry doors. We are issuing this AD to detect and correct fatigue cracks that could extend and fully sever the frame, which could result in development of skin cracks that could lead to rapid depressurization of the airplane.