Airworthiness Directives; Boeing Model 747 Series Airplanes

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T96-26-52 that was sent previously to all known U.S. owners and operators of Boeing Model 747 series airplanes by individual telegrams. This AD requires repetitive inspections of the access doors to the midspar/spring beam fuse pins on all engine pylons to detect cracks on the external surface; repetitive inspections of each midspar/spring beam fuse pin to detect if it protrudes beyond its mating nut by a specified distance; and repair of any discrepancy found. This action is prompted by a report indicating that a fuse pin had migrated on an inboard spring beam fitting on the Number 1 engine pylon of a Boeing Model 747-400 airplane. The actions specified by this AD are intended to prevent migration of this fuse pin, which, if not detected and corrected in a timely manner, could result in failure of the engine pylon and consequent separation of the engine from the wing.