On October 7, 1999, a Bell 206B (registration N6624N) operated by Arizona Heliservices Inc. was involved in an aviation accident near Apache Junction, AZ. Investigators recorded the probable cause as: Oil starvation and seizure of the engines Nos. 6 and 7 bearings due to a clogged oil jet, which resulted in a total loss of engine power. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 8 related events involving the same aircraft type or operator are linked below.
During cruise at 600 ft AGL, a helicopter experienced high oil pressure and torque, chip light illumination, and engine failure during descent. Autorotation resulted in tail cone separation after the left skid entangled in a bush.
Accident Narrative
While in cruise flight at approximately 600 feet above ground level, the pilot observed that the engine oil pressure was high and the torque gauge exceeded its high limits. Subsequently, the engine chip light illuminated. The pilot initiated a descent for an immediate landing. At an altitude of approximately 75 to 100 feet above ground level, the engine stopped producing power. The pilot performed an autorotation to the ground. During the landing, the left skid toe became entangled in a large bush and separated. The main rotor blades struck and severed the tail cone aft of the horizontal stabilizer.
Engine Examination
A teardown examination of the engine was conducted. The mechanic reported that the No. 6 and No. 7 bearings showed evidence of heat distress and oil starvation. When the mechanic blew through the oil jet for the No. 6 and No. 7 bearings, he heard a pop and something emerged. He opined that it might have been a piece of carbon, which could have prevented the flow of oil into the turbine. The mechanic stated that all other components of the lubrication system were intact and functional. No other discrepancies were found.