Supplement No. 1 to Service Bulletin No. 566

Crankshaft Replacement in Lycoming Engines


DATE: November 30, 2005


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

Lycoming counterweighted (L)O-360, (L)IO-360 and AEIO-360 engines rated at any horsepower as listed in Table 1.

Any overhauled or repaired Lycoming counterweighted (L)O-360, (L)IO- 360 or AEIO-360 engine that has had a crankshaft replaced after March 1, 1999 with a crankshaft serial number listed in Table 2.

Lycoming crankshafts with a crankshaft serial number listed in Table 2 shipped as a spare after March 1, 1999. These crankshafts may be installed in any of the engine models listed above.


Within next 50 hours of operation or 6 months from the date of this Supplement No. 1 to Service Bulletin No. 566, 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 cylinder engines.

Service Bulletin No. 566

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