AD FAA-2013-0326

We are superseding Airworthiness Directive (AD) 2004-12-07 for certain The Boeing Company Model 757 series airplanes equipped with Rolls-Royce RB211 engines. AD 2004-12-07 required modification of the nacelle strut and wing structure; and for certain airplanes, repetitive detailed inspections of certain aft bulkhead fasteners for loose or missing fasteners, and corrective action if necessary. For certain other airplanes, AD 2004-12-07 required a one-time detailed inspection of the middle gusset of the inboard side load fitting for proper alignment, and realignment if necessary; a one-time eddy current inspection of certain fastener holes for cracking, and repair if necessary; and a detailed inspection of certain fasteners for loose or missing fasteners, and replacement with new fasteners if necessary. This new AD specifies a maximum compliance time limit. This AD was prompted by reports indicating that the actual operational loads applied to the nacelle are higher than the analytical loads that were used during the initial design. We are issuing this AD to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut.