On September 29, 1994, a Bell UH-1B (registration N41870) was involved in an aviation accident near Ozark, AL. Investigators recorded the probable cause as: The number one, three, and four main bearings failed because of a lack of lubrication. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a positioning flight, an engine chip detector illuminated and later re-illuminated. The pilot continued toward the airport but initiated an autorotation after a low rotor speed warning. The aircraft collided with trees near a field. Post-accident examination revealed three main bearings failed due to lack of lubrication.
Flight Events
While in cruise during a positioning flight, the engine chip detector illuminated. A few seconds later, it extinguished. The terrain below was heavily wooded, and the destination airport was approximately three miles away. The pilot decided to continue toward the airport. Shortly afterward, the chip light re-illuminated, prompting the pilot to search for a landing site. Then the low rotor speed warning horn sounded, and the pilot began an autorotation. However, he was unable to reach an open field and collided with trees at the edge of a field.
Post-Accident Examination
During the post-accident examination of the engine, the number one, three, and four main bearings were found to have failed because of a lack of lubrication.
Probable cause
The number one, three, and four main bearings failed because of a lack of lubrication.