The FAA today issued an emergency airworthiness directive for most Lycoming 540 engines manufactured or overhauled between November 1996 and November 1998. These engines may have a defective crankshaft gear-retaining bolt. Failure of the bolt can lead to a total loss of engine power. The AD affects some 3,800 engines, including some 100 engines covered in the previous crankshaft AD.
It affects aircraft built by some 23 different manufacturers, including Cessna 182 and 206, Mooney TLS, and a range of Piper models.
The AD requires that the bolt be replaced within seven days or 10 hours time-in-service.
"Lycoming assures AOPA that it has plenty of replacement bolts in stock," said Andy Werking, AOPA associate director of regulatory policy. "After aircraft owners have contacted Lycoming, they may contact the AOPA Pilot Information Center (800/872-2672) so we can monitor how the manufacturer handles and processes their parts requests and warranty claims."
Lycoming will extend parts and labor warranty coverage for the AD-required repair provided owners return the replaced bolts (identified by engine serial number) to the company.
The problem is that Lycoming installed or shipped as spare parts more than 3,700 zinc-plated bolts, rather than the required cadmium-plated bolts. Some 1,200 of the bad bolts were installed in engines built or overhauled by Lycoming. Nearly 2,600 bolts were shipped to the field and could be installed in engines serviced by other repair shops.
Covered engines include the Lycoming AEIO-540, IO-540, LTIO-540, O-540, and TIO-540 engines listed by serial number in Lycoming Service Bulletin 554. However, 540-series engines with single-drive dual magnetos and O-540-F series engines covered under AD 99-03-05 are not included.