Airworthiness Directives; CFM International CFM56-2, -3, -3B, - 3C, and -5 Series Turbofan Engines

摘要

This notice proposes the revision of an existing airworthiness directive (AD), applicable to CFM International (CFMI) CFM56-2, -3, - 3B, -3C, and -5 series turbofan engines, that currently requires repetitive magnetic chip detector (MCD) inspections and removal from service of certain No. 3 bearings. This action would remove the requirement for MCD inspections for certain No. 3 bearings if the bearing has 6,000 or more hours time in service since new, extend the removal from service date for certain No. 3 bearings, change the inspection interval for certain No. 3 bearings, delete a specific No. 3 bearing part number, and replace reference to specific maintenance manuals with service bulletins. Other requirements of the current AD would remain unchanged and be carried over into the proposed AD. This proposal is prompted by additional data which demonstrates a reduced bearing failure rate after a period of time in service, therefore, an acceptable level of safety can be maintained with a relaxation of some of the current AD requirements. The actions specified by the proposed AD are intended to prevent a No. 3 bearing failure, and a subsequent inflight engine shutdown.