Airworthiness Directives; CFM International, S.A. CFM56-5C4/1 Series Turbofan Engines

The FAA is superseding an existing airworthiness directive (AD) for CFM International, S.A. CFM56-5C4/1 series turbofan engines. That AD currently requires that the low pressure turbine (LPT) conical support, part number (P/N) 337-002-407-0, be removed from service at or before reaching the cyclic life limit of 9,350 cycles-since-new (CSN). This AD requires that the same P/N LPT conical support be removed from service before reaching the new, relaxed cyclic life limit of 20,000 CSN. This AD results from CFM International, S.A. performing a life extension study of the LPT conical support, P/N 337-002-407-0. We are issuing this AD to prevent LPT conical supports from remaining in service beyond their certified cyclic life limit, which could result in an uncontained engine failure and damage to the airplane.