On March 27, 1989, a Beech F33A (registration N3042Z) operated by Ruth M. Davis was involved in an aviation accident near Lamar, CO. Investigators recorded the probable cause as: FAILURE OF AN ALTERNATOR BEARING WHICH RESULTED IN TOTAL LOSS OF ELECTRICAL POWER AFTER THE BATTERY BECAME DISCHARGED, AND FAILURE OF THE PILOT TO INSURE THE GEAR WAS FULLY EXTENDED DURING A PRECAUTIONARY LANDING. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a cross-country flight, an alternator warning light prompted a diversion to Lamar, Colorado. After electrical depletion, the pilot manually extended gear and landed on a road; all three gear collapsed and the aircraft went off the road. Investigation found an alternator bearing failure; no cause for low oil pressure was found.
Narrative
During a cross-country flight, the alternator out light illuminated. The pilot diverted to the closest airport, which was in Lamar, Colorado. By the time the aircraft arrived at Lamar, the electrical system had become depleted. Because the landing gear extension normally relies on the electrical system, the pilot was unable to extend the gear electrically. She then manually extended the landing gear to what she thought was the fully extended position. The engine oil pressure gauge was indicating low, leading the pilot to choose to land on a road.
On landing, all three landing gear collapsed. Before the aircraft came to a stop, it went off the side of the road and was further damaged.
Investigation
A post-accident inspection of the aircraft revealed that an alternator bearing had failed. No reason for the reported drop in oil pressure was found.