Aviation Accident Summaries

Aviation Accident Summary CEN09LA209

Bellefontaine, OH, USA

Aircraft #1

N9348S

BEECH B24R

Analysis

During cruise flight the pilot noticed abnormal engine noises and a partial loss of engine oil pressure. He immediately diverted to the nearest airport, but during the turn to base leg the engine oil pressure dropped to zero pounds per square inch and the engine seized. The airplane was not in a position to reach the runway threshold or to clear the airport perimeter fence. During the landing rollout the airplane impacted the airport perimeter fence, damaging both wings and the nose landing gear. An engine teardown examination revealed that the Number 3 cylinder connecting rod assembly had separated from its corresponding crankshaft journal. The journal surface was blue in color, consistent with exposure to excessive heat and lack of lubricant. The oil suction screen was obstructed with bearing material. The Number 3 cylinder connecting rod cap was found jammed beneath the counterbalance weight. One of the two connecting rod stretch bolts remained intact. The corresponding nut was found finger tight. The measured torque for the Number 2 cylinder connecting rod bolts were significantly less than the manufacturer's specification. The engine had accumulated a total of 3,799 hours since new and 492.7 hours since its last overhaul in 1999. The engine was last inspected 23.9 hours before the accident occurred.

Factual Information

On March 15, 2009, at 1500 eastern daylight time (edt), a Beech B24R (Sierra), N9348S, owned and piloted by a private pilot, was substantially damaged during a forced landing following an en route loss of engine power near Bellefontaine, Ohio. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot and his passenger were not injured. The flight departed Grimes Field Airport (I74), near Urbana, Ohio, at 1445 edt and was en route to Bluffton Airport (5G7), near Bluffton, Ohio. According to the pilot, the airplane was in cruise flight when he noticed abnormal engine noises and a partial loss of engine oil pressure. He immediately diverted to the nearest airport, Bellefontaine Regional Airport (KEDJ), and entered downwind for runway 7 (4,999 feet by 100 feet, asphalt). During the turn to base leg, the engine oil pressure dropped to zero pounds per square inch and the engine seized. He established best glide speed and continued the turn onto final approach. The pilot reported that the airplane was not in a position to reach the runway threshold, or to clear the airport perimeter fence. He lowered the landing gear and selected full flaps prior to landing in the grass area outside of the airport perimeter fence. During landing rollout the airplane impacted the airport perimeter fence, damaging both wings and the nose landing gear. An engine teardown examination revealed that the number 3 cylinder connecting rod assembly had separated from its corresponding crankshaft journal. The crankshaft journal surface was blue in color, consistent with exposure to excessive heat and lack of lubricant. The oil suction screen was obstructed with bearing material. The number 3 cylinder connecting rod cap was found jammed beneath the counterbalance weight. One of the two connecting rod stretch bolts remained intact. The corresponding nut was found finger tight. The measured torque for the upper and lower stretch bolts on the number 2 cylinder connecting rod was 15 foot-pounds (ft-lbs) and 6 ft-lbs, respectively. The manufacturer specified torque value was 40 ft-lbs. The Lycoming IO-360-A1B6 engine, serial number L-13455-51A, had accumulated 492.7 hours since its last overhaul in September 1999 following a propeller strike.

Probable Cause and Findings

The inadequate torque of the Number 3 cylinder rod bolts by maintenance personnel, which resulted in a failure of the connecting rod and a total loss of engine power.

 

Source: NTSB Aviation Accident Database

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