Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to CFM International, S.A. CFM56-3, - 3B, and -3C series turbofan engines. This proposal would discontinue use of certain lubricants no longer on the manufacturer's approved list. In addition, this proposal would require a one-time fan disk dovetail wear measurement, and if wear exceeds certain limits, require an ultrasonic inspection for cracks in the fan disk, and, if necessary, require removal from service of fan disks and replacement with serviceable parts. This proposal is prompted by reports of fan disk heavy wear and cracks. The actions specified by the proposed AD are intended to prevent fan disk failure, which could result in an uncontained engine failure and damage to the aircraft.