Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 757 series airplanes equipped with Rolls-Royce RB211 engines. The existing AD currently requires modification of the nacelle strut and wing structure; 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, the existing AD requires 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; a detailed inspection of certain fasteners for loose or missing fasteners; and replacement with new fasteners if necessary. Since we issued that AD, a compliance time error was discovered, which could allow an airplane to exceed the acceptable compliance time for addressing theunsafe condition. This proposed AD would specify a maximum compliance time limit. We are proposing this AD to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut.