Service Bulletin No. 554

Crankshaft Gear Retaining Bolt Replacement


DATE: September 30, 2002


All engines listed in Table 1. All O, IO, (L)TIO or AEIO-540 engines that have had a crankshaft bolt replaced during maintenance or overhaul between November 27, 1996 and November 10, 1998.


Within the next ten (10) hours of operation or seven (7) days, whichever occurs first.

Lycoming has determined that a metallurgical condition has caused crankshaft gear retaining bolts to fail in service. The crankshaft gear drives both magnetos and the camshaft. Failure of the retaining bolt results in total loss of power without prior warning.

Get It Exchanged

Use our Engine Exchange Program to order a new, rebuilt, or overhauled engine to experience more airtime and less downtime.