Airworthiness Directives; Continental Motors, Inc. (CMI) Reciprocating Engines

We are superseding an existing airworthiness directive (AD) for certain Continental Motors, Inc. (CMI) models TSIO-520, TSIO-550-K, TSIOF-550K, and IO-550-N series reciprocating engines with new or rebuilt CMI starter adapters installed between January 1, 2011 and November 20, 2011. That AD currently requires replacing affected CMI starter adapters with starter adapters eligible for installation. This AD requires the same actions, but to an expanded population of reciprocating engines. This AD was prompted by two additional reports received of fractures in starter adapter gear shafts in certain additional part number (P/N) CMI starter adapters since we issued the existing AD. We are issuing this AD to prevent starter adapter gear shaft failure which could cause oil scavenge pump failure and engine in-flight shutdown.