Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Austro Engine GmbH Model E4 and E4P engines. This proposed AD was prompted by reports of piston failures and the determination that certain batches of pistons were manufactured with a dimensional deviation in the piston pin bore and piston diameter. This proposed AD would require repetitive engine oil analysis for aluminum content outside the acceptable limits and, if necessary, replacement of the pistons, piston rings, con-rods assembly, and crankcase or, as an alternative, replacement of the engine core. The FAA is proposing this AD to address the unsafe condition on these products.