Service Bulletin No. 553

Crankshaft Inspection for Lycoming Six Cylinder Turbocharged Engines

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DATE: September 16, 2002


Those Lycoming TIO and LTIO-540 engines listed in Table 1 below.

Any field overhauled Lycoming TIO and LTIO-540 engine rated at 300 horsepower or higher that has a crankshaft installed with a serial number listed in Table 2.

Any Lycoming IO-540 engine that has an aftermarket turbocharger installed under an STC and has a crankshaft serial number listed in Table 2.


Within next 50 hours of operation or six months, whichever occurs first.

Lycoming has received a field report of a broken crankshaft in a six-cylinder turbocharged engine. The report affected a product outside of the range recalled by Service Bulletin No. 552. Metallurgical testing indicates that the cause is material related. Lycoming requires that affected crankshafts be inspected. During the inspection, three core samples will be removed from the crankshaft propeller flange by a Lycoming authorized representative.

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Related Publication

Supplement No. 1 to Service Bulletin No. 553

For more information on Crankshaft Inspections, refer to Supplement No. 1 to Service Bulletin No. 553.