Airworthiness Directives; Teledyne Continental Motors IO-360, TSIO-360, LTSIO-360, IO-520, and TSIO-520 Series Reciprocating Engines

摘要

This notice revises a proposal to issue an airworthiness directive (AD), applicable to certain Teledyne Continental Motors (TCM) IO-360, TSIO-360, LTSIO-360, IO-520, and TSIO-520 series engines. Airworthiness directive 87-23-08 currently requires ultrasonic inspections for sub-surface fatigue cracks in crankshafts installed in TCM IO-520 and TSIO-520 series engines, and replacement of the crankshaft if a crack is found. The proposed AD would have superseded AD 87-23-08 by expanding the applicability of the AD to include IO-360, TSIO-360, LTSIO-360, and LTSIO-520 series engines, requiring the removal of all crankshafts manufactured using the airmelt process on all of the affected engine models, and replacement with crankshafts manufactured using the vacuum arc remelt (VAR) process. The proposed AD would have eliminated the ultrasonic inspections for the TCM IO-520 and TSIO-520 series engines. That proposed rule was prompted by reports of crankshaft failures due to sub-surface fatigue cracking on engines that had been inspected in accordance with the current AD. This action revises the proposed rule by superseding AD 87-23-08 and incorporating the ultrasonic inspection requirements i