Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to General Electric Company CF6-80A3 series turbofan engines. The existing AD currently requires initial and repetitive on-wing borescope inspections of the left hand aft engine mount link assembly for cracks, bearing migration, and, bearing race rotation, and if necessary, replacement with serviceable parts. This proposal would require initial and repetitive visual inspections of both left hand and right hand aft engine mount link assemblies for separations, cracks, and bearing race migration. Cracked or separated parts would have to be replaced prior to further flight. If spherical bearing race migration is discovered, a borescope inspection for cracks is also proposed. If no cracks are discovered by the additional borescope inspection, assemblies would have a 75-cycle grace period for remaining in service before replacement. Finally, installation of improved aft engine mount link assemblies would constitute terminating action to the inspections of this proposed AD. This proposal is prompted by a recent analysis of internal bearing friction and bearing migration and inspections which revealed migrated spherical bearing races on two CF6-80A3 series and ten CF6-80C2 series aft engine mount links. The actions specified by the proposed AD are intended to prevent aft engine mount link failure, which can result in adverse redistribution of the aft engine mount loads and possible aft engine mount system failure.