NYC98LA001

The Cessna 210 was in cruise when the engine lost power. The pilot descended through an overcast and made a forced landing in an open field. During a ground slide with the landing gear retracted, the airplane passed over a creek, and received substantial damage. A torque check conducted before engine disassembly revealed low torques on a nose case bolt, and some cylinder through bolts on the front and middle cylinders. Engine disassembly revealed that the crankshaft had fractured near the rear of the number 2 main bearing, located between the middle and rear cylinders. The investigation found that the bearing had shifted to the rear of the engine and made contact with the short cheek of the crankshaft. The number 4 cylinder was replaced 469 hours prior to the accident, and the numbers 1, 2, 3, 5, and 6 cylinders were replaced 367 hours prior to the accident.

On October 1, 1997, about 1225 eastern daylight time, a Cessna T210L, N29134, was substantially damaged during a forced landing near Great Barrington, Massachusetts. The certificated commercial pilot and passenger were seriously injured. Visual meteorological conditions prevailed for the business flight which departed from New Philadelphia, Ohio, about 1000. The flight was operated on an Instrument Flight Rules (IFR) flight plan under 14 CFR Part 91.

The flight was in radio contact with Bradley Approach Control. The pilot had been cleared from 11,000 feet to 9,000 feet, and then to 5,000 feet. In the NTSB Pilot/Operator Aircraft Accident Report, the pilot stated:

"...Descended through 7,000 [feet] at cruise settings. Thump and vibration in engine, oil pressure dropped from usual setting to zero immediately. Secured throttle, prop & mixture. Informed appr. control, asked for nearest field, received Barrington, and confirmed with LORAN. It was 14 miles behind us. Turn to west and glide clean at 100 - 110 kts [knots]. No clearing seen on ground. Airport seen about 5,000 [feet] alt[itude]. At 4,000 [feet] determined A/C would not clear hill between airport. Turned right (northerly) to follow valley. Lost approach control who was notifying people on ground of situation. Sighted road, paved, narrow, winding power poles and traffic both directions. Followed valley, sighted meadow, secured mags, alt[ernator], batt, unlocked doors, gear and flaps left up. Slight left bank to line up (200 - 300 FT), alt[itude]. Speed still at glide. Entered weeds reported to be 5 FT tall. Started flare, hit unseen far side of brook with violent jolt. Plane came to rest. Both [occupants] were conscious and bleeding. Rolled out side doors, crawled 10-20 FT, People arrived, taken to hospital."

An inspector from the Federal Aviation Administration (FAA) reported that the airplane stopped after it passed over a creek. The high weeds in the creek obscured its presence. Examination of the airplane revealed that the engine was partially twisted away from the firewall, and there was torn skin on the belly of the airplane. Initial examination of the engine revealed that when the propeller was rotated, the pistons in cylinders 1 and 2 did not move.

The engine was taken to Mattituck Air Base, Mattituck, New York, for further examination. The FAA inspector reported:

"...The engine was found to have a broken crankshaft near the rear section between cylinders 1 and 2 [rear of engine] and cylinders 3 and 4 [middle of engine]. The number 2 main bearing was out of place and shifted toward the rear of the engine. The bearing had made contact with the short cheek of the crankshaft and friction heat initiated the crankshaft failure...."

"...The reason for the bearing failure is indeterminable at this time. The cylinder heads were replaced 367.4 hours before the failure and if they were not torqued properly, could have been a contributing factor, although all torque checks are inconclusive."

The investigation revealed that on January 10, 1995, the number 4 cylinder was replaced, at an engine total time of 777.1 hours. On May 18, 1995, the numbers 1, 2, 3, 5, and 6 cylinders were replaced, at an engine total time of 872.9 hours. The engine total time at the time of the accident was 1240.3 hours.

The investigation further revealed that the main bearings were held in place by each side of the engine case. The case was held together with case bolts, and cylinder through bolts. A check of the torque values on the engine case bolts and cylinder through bolts prior to engine disassembly, revealed low torque values on a nose case bolt, and some cylinder through bolts on the front and middle banks of cylinders of the engine.

A check with Teledyne Continental revealed that they did not have a procedure in place to require periodic checks of torque values.