Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require repetitive detailed visual inspections for corrosion, and repetitive high frequency eddy current (HFEC) inspections for cracks, of the upper link assembly on the number 2 and number 3 engine struts, and corrective actions, if necessary. This proposal is prompted by reports of corrosion and cracks located at the four fasteners that attach to the aft end to the upper link assembly on the number 2 and number 3 engine struts. The actions specified by the proposed AD are intended to prevent failure of the upper link due to cracking or corrosion, subsequent damage to other strut support structure, and in-flight separation of an engine from the airplane.