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

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Teledyne Continental Motors (TCM) IO-520 and TSIO-520 series reciprocating engines, that currently requires ultrasonic inspection for subsurface fatigue cracks in crankshafts installed in TCM IO-520 and TSIO-520 series engines and replacement of the crankshaft if a crack is found. This amendment adds a requirement to remove crankshafts manufactured using the airmelt process and replace them with crankshafts manufactured using the vacuum arc remelt (VAR) process, incorporates new ultrasonic inspection criteria in the AD, adds engine series TCM IO-360, TSIO-360, LTSIO-360, IO-520, LIO- 520, TSIO-520, LTSIO-520 and Rolls-Royce, plc IO-360 and TSIO-360 to the applicability, and revises the economic impact analysis. This amendment is prompted by reports of crankshaft failures due to subsurface fatigue cracking on engines that had been inspected in accordance with the current AD. The actions specified by this AD are intended to prevent crankshaft failure and subsequent engine failure.