Airworthiness Directives; Continental Motors, Inc. Reciprocating Engines

We are adopting a new airworthiness directive (AD) for certain Continental Motors, Inc., (CMI) San Antonio (formerly known as Airmotive Engineering Corp. (AEC)), replacement parts manufacturer approval (PMA) cylinder assemblies marketed by Engine Components International Division (ECi). On July 17, 2015, AEC was purchased by CMI and is now operating as "Continental Motors--San Antonio." These cylinder assemblies are used on all CMI model -520 and -550 reciprocating engines, and on all other CMI engine models approved for the use of model -520 and -550 cylinder assemblies, such as the CMI model -470 when modified by supplemental type certificate (STC). This AD was prompted by reports of multiple cylinder head-to-barrel separations and cracked and leaking aluminum cylinder heads. This AD requires removal of the affected cylinder assemblies, including overhauled cylinder assemblies, according to a phased removal schedule. We are issuing this AD to prevent failure of the cylinder assemblies, which could lead to failure of the engine, in-flight shutdown, and loss of control of the airplane.