Squawk Box

March 2003 Issue

Bolt Confusion

AD on Lycoming crank bolts complicated by supplier part numbers

The following information is derived from the FAA’s Service Difficulty Reports and Aviation Maintenance Alerts.


Some operators of aircraft with Lycoming -540 series engines who were hit by a pair of crankshaft bolt ADs last year got another letter from the FAA: Never mind.

The emergency AD and the superceding AD issued in December required owners of Lycoming’s big six-cylinder engines to replace the crankshaft gear retention bolt. The AD cut across applications, applying to aerobatic engines, turbos, left-turning engines and for airplanes and helicopters. Although it applied only to those engines with a Lycoming part number STD-2209 retaining bolt, many people didn’t mak...

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