Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-200, - 300, and -400 series airplanes. This proposal would require replacement of fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut with new corrosion-resistant pins. This proposal is prompted by reports of cracked fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut due to fatigue and corrosion. The actions specified by the proposed AD are intended to prevent cracking or corrosion of the fuse pins of the nacelle strut, which could result in failure of the fuse pin and strut-to-wing attachment, and consequent loss of the strut and separation of the engine from the airplane.