NTSB Identification: MIA99LA069.
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Accident occurred Tuesday, January 26, 1999 in CHARLESTON, SC
Probable Cause Approval Date: 04/19/2001
Aircraft: Beech A36, registration: N4976M
Injuries: 1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot reported that about 7 minutes after takeoff the airplane's engine lost oil pressure and started to lose oil, followed by a loss of engine power. The airplane started a descent that the pilot could not arrest, and continued to descend at a rate of about 100-200 feet per minute. The pilot then heard, 'a loud bang...a shudder occurred in the engine compartment, and the engine lost power.' The pilot banked the airplane, and headed towards a clearing. The engine compartment appeared to be on fire, and smoke began to enter the cockpit. He elected to make a forced landing in a field. The engine was examined at the crash site, and a hole was noted in the case at the No. 4 cylinder. Oil was observed on the No. 4 cylinder wall, the oil dip stick did not show any oil, and there was evidence that oil had leaked out of the engine. The engine was examined on February 12, 1999, and the examination revealed that oil had leaked at the engine oil filter adapter. In addition, there were more threads showing on one stud than on the other. A torque wrench was used to check torque on the nuts. It was noted that one nut rotated 1 1/2 rotations before reaching the specified torque. The other nut rotated 1 rotation before reaching torque. The oil filter adapter was removed for further examination, and revealed that the gasket was found with a gap at the corner with a opening of about 1/16 of an inch. It was concluded, that the leak caused the engine to exhaust the oil supply, causing the No. 4 cylinder connecting rod to fail, which resulted in a total loss of engine power.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the total loss of engine power caused by an oil leak at the oil filter adapter, resulting in a broken connecting rod, a subsequent forced landing and impact with rough terrain. Full narrative available
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