Service Bulletin No. 552

Crankshaft Replacement in Lycoming TIO and LTIO-540 Engines Rated at 300 Horsepower and Higher

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Supersedes and Replaces Service Bulletin No. 550

DATE: August 16, 2002


Service Bulletin No. 552 applies only to TIO and LTIO-540 engines rated at 300 horsepower or higher.

Engines that previously complied with Service Bulletin No. 550 are also affected by Service Bulletin No. 552.


Before further flight.

Lycoming has received several field reports of broken crankshafts in six-cylinder turbocharged engines rated at 300 horsepower or higher. The problem is related to the material used in these crankshafts. Due to the nature of the problem, there is no field process currently available to identify crankshafts potentially affected. The engines assembled with the suspect crankshaft are listed in Table 1 below. Affected crankshaft serial numbers are listed in Table 2.

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Related Publication

Supplement No. 1 to Service Bulletin No. 552

For more information on Crankshaft Replacement, refer to Supplement No. 1 to Service Bulletin No. 552.