CHARLESTON, SC, USA
N4976M
Beech A36
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.
On January 26, 1999, about 1600 eastern standard time, a Beech A36, N4976M, registered to an individual lost engine power and impacted with the ground during a forced landing near Charleston, South Carolina. Visual meteorological conditions prevailed at the time, and a VFR flight plan was filed for the 14 CFR Part 91 personal flight. The airplane sustained substantial damage. The commercial-rated pilot reported no injuries. The flight was en route to Hilton Head, South Carolina, and had departed Charleston at 1545. The pilot reported that during climb the airplane's engine lost oil pressure and started to lose oil, followed by a loss of engine power. 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. According to the pilot's summary and synopsis of circumstances, about 7 minutes after takeoff, he was cleared directly to Hilton Head, South Carolina, and was to maintain 2,500 feet. About 12 miles from the Charleston Airport, "...suddenly and without warning the propeller RPMs began to increased from 2,400 to 2,700." The pilot turned the airplane towards the Charleston Airport, advised Air Traffic Control (ATC) of the propeller overspeed condition, and that he intended to return to Charleston. He declared an emergency, and ATC cleared the airspace for the flight. About 2 to 3 minutes after the initial increase in rpm, the propeller rpm increased to 3,000 rpm, and changed pitch. 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. He said, the engine compartment appeared "...to be on fire, and smoke began to enter the cockpit." Before landing the pilot extended the landing gear, moved the fuel valve to the "OFF" position, turned off the mixture, and the electrical system. The landing site was a plowed field, and was plowed perpendicular to the direction of flight. The pilot elected to land straight ahead. At touchdown the airplane "appeared to slide first on its tail, then the landing gear hit a plowed furrow, and the aircraft came to an upright stop." The engine was examined under the supervision of the FAA, on February 12, 1999, at Manning Aircraft Inc., Manning, South Carolina. Examination of the engine revealed that there was a hole 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. Low pressure air was introduced into the oil pressure line that ran to the gauge on the instrument panel, revealing an oil leak 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 once 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 (see Continental Motor's report, an attachment to this report).
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.
Source: NTSB Aviation Accident Database
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