Service Bulletin No. 566

Crankshaft Replacement in Lycoming Engines

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DATE: July 11, 2005


Any Lycoming engine model specified below manufactured, rebuilt, overhauled or repaired after March 1, 1999:

Lycoming O-540, IO-540, AEIO-540 and TIO-540 engines rated at 290 horsepower or lower as described in Section 1 and listed in Table 1.

Lycoming IO-540-P, -S, -AA engines rated at 250-290 horsepower by Lycoming as described in Section 2 and listed in Table 2. Lycoming IO-540 and AEIO-540 engines rated at 300 horsepower as described in Section 2 and listed in Table 2.

Lycoming counterweighted (L)O-360, (L)IO-360 and AEIO-360 engines rated at any horsepower as described in Section 3 and listed Table 3.

Lycoming crankshafts with a crankshaft serial number listed in Table 4 shipped as a spare after March 1, 1999. These crankshafts may be installed in any of the engine models listed above.

NOTE: Engines that have complied with Service Bulletin No. 552 or Service Bulletin No. 553 are not affected by this Service Bulletin.


Within next 50 hours of operation or 6 months from the date of this Service Bulletin, whichever occurs first.

Lycoming has continued to analyze crankshafts in service. This analysis indicates that replacement of certain crankshafts is warranted. Therefore, Lycoming is recalling certain crankshafts in the specified four and six cylinder engines.

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Related Publication

Supplement No. 1 to Service Bulletin No. 566

For more information on Crankshaft Retirement, refer to Supplement No. 1 to Service Bulletin No. 566.