NTSB Identification: FTW96IA248.
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Scheduled 14 CFR
Incident occurred Tuesday, June 11, 1996 in ENID, OK
Probable Cause Approval Date: 04/29/1997
Aircraft: Fairchild SA227-DC, registration: N850LS
Injuries: 8 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
The airplane experienced an uncommanded shut down of the right engine during initial climb to altitude. An emergency was declared, and an uneventful single engine landing was made at the departure airport. Subsequent to the incident, metallic chips were found on the chip detector. The bearings of the accessory gear housing assembly (P/N 3103601-6) was missing all of the balls. Fragments of these ball bearings were found in the bottom of the engine case. Examination of the bearing races revealed pitting and scoring. According to the operator's diagnostics, the disintegration of the bearings allowed the gear shaft to drop down and contact the gears of the accessory drive idler gear assembly. Subsequently, the fuel pump drive gear was not driven, causing the engine to be starved of fuel. Inspection of the idler gear assembly revealed sheared gear teeth. Examination of the gearbox oiling system, revealed no evidence of failure or thermal distress prior to the initial bearing failure. The engine manufacturer had recently issued Service Bulletins addressing the installation of heavier duty gear assemblies in applicable engine installations.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: failure of the accessory drive bearing, causing the accessory drive gear teeth to shear and disengage the fuel pump accessory drive shaft, resulting in a disabled fuel pump and subsequent fuel starvation. Full narrative available
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