Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for certain 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. This AD was prompted by a report of a cracked reveal made from a casting found within a group of airplanes that should have machined reveals made only from 6061 aluminum. This AD requires an inspection to determine the material of the number 3 main entry door (MED) corner reveal, repetitive inspections of certain reveals for cracking, and corrective action if necessary. This AD also requires repetitive inspections for cracking of 6061 machined aluminum one-piece corner reveals, and replacement with 6061 machined aluminum two-piece corner reveals if necessary, which terminates certain repetitive inspections. We are issuing this AD to detect and correct fatigue cracking of the lower forward corner reveal of the number 3 MEDs, which could lead to the door escape slide departing the airplane when the door is opened and the slide is deployed, and consequent injuries to passengers and crew using the door escape slide during an emergency evacuation.