Textron Lycoming (Williamsport, Pennsylvania) 540 and 720 series light aircraft engines are the subject of a Federal Aviation Agency Emergency Airworthiness Directive. Defective bearings were found in the engine nose reduction gear.

Textron Lycoming identified a production run of 922 nose bearings, part number LW-13885, as defective. The date stamp on the bearings is 6-00. Approximately 850 of those bearings were installed in 540 and 720 series light aircraft engines around the world before the problem was discovered. New engine builds, factory overhauls and some field overhauls would have installed the bearings between August 2000 and January 2001.

Engine series affected are the O-540, IO-540, LTIO-540, AEIO-540 and IO-720. O signifies an opposed-cylinder engine, I for fuel injection, and T for turbocharging.

These bearing failures have generally occurred very early in the operating cycle, often when the engine has fewer than 25 hours. Nose bearing failure can be predicted by the presence of metallic debris trapped in the oil, filter and oil filter screen, so the FAA's Airworthiness Directive requires frequent checks of the oil, filter, and oil filter screen. The Airworthiness Directive does not require replacing the nose bearings unless metallic debris is found; replacing the nose bearings involves a complete and expensive engine overhaul.

Although the problem affects engines in operation around the world, the California Highway Patrol has been particularly hard hit by bearing failures. The CHP recently purchased 14 Cessna 206 aircraft equipped with the 540 series engines. So far, 12 of the $400,000 aircraft have been delivered; three have already experienced catastrophic engine failure and one had a bearing problem detected just prior to failure.

In response, the CHP has grounded its fleet and issued a statement strongly critical of Cessna and Textron Lycoming for its handling of the situation.

CHP Commissioner Dwight Helmick said, "I'm really disappointed that Cessna did not act in an upfront manner to warn us of this danger. They never even mentioned the FAA bulletin even after we reported our three problems late last week."