Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 727 airplanes. This proposal would require an inspection of the bolts used to attach the forward cone bolt to the engine flange to determine if the attachment bolts are either H-11 steel bolts or cadmium-plated bolts. This proposal would also require replacement of either H-11 steel bolts or cadmium-plated bolts with new corrosion-resistant steel bolts. This action is necessary to prevent undetected cracking of the H-11 bolts or excessive wear of the cadmium-plated bolts, which would compromise the primary load path of the engine support and could result in separation of the engine from the airplane. This action is intended to address the identified unsafe condition.