Airworthiness Directives; Boeing Model 747 Series Airplanes Powered By Rolls Royce Model RB211 Series Engines

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T96-26-51 that was sent previously to all known U.S. owners and operators of certain Boeing Model 747 series airplanes powered by Rolls Royce Model RB211 series engines by individual telegrams. This AD requires a one-time inspection to detect cracks and corrosion of various areas at all four engine pylons, and repair of any cracked or corroded engine pylon. This action is prompted by reports of cracking of the aft torque bulkhead at the number 1 and number 2 engine pylons. The actions specified by this AD are intended to detect and correct such cracking, which could result in failure of the pylon and consequent separation of the engine from the wing.