Tampa, FL, USA
N2263S
CESSNA 210L
The airplane was climbing when the engine lost partial power. The pilot turned back toward the departure airport and the engine lost total power. During the subsequent forced landing, the airplane struck a fence, which resulted in substantial damage to the fuselage and left wing. Examination of the engine crankcase halves revealed fretting at the No. 2 main bearing saddle surfaces, which indicated insufficient clamping force during assembly due to inadequate torque on the bolts. The No. 2 main bearing was broken into pieces, which were observed in the oil sump. Examination of the crankshaft revealed a fatigue fracture that initiated in the fillet between the No. 2 main journal and the cheek at the aft end of the journal. The fatigue crack features observed in the No. 2 main bearing were secondary and were a result of high stresses on the bearing as it shifted. This most likely resulted from insufficient bearing crush due to insufficient clamping force on the crankcase saddle surfaces. According to the engine logbooks, a 100-hour maintenance inspection occurred 19.5 hours prior to the accident, which required a mechanic to verify that the crankcase bolts did not exhibit looseness.
On June 8, 2010, about 2039 eastern daylight time, a Cessna 210L, N2263S, was substantially damaged during a forced landing to a vacant football field near a school in Tampa, Florida. The airplane was registered to and operated by Flight Express Inc. The certificated commercial pilot was not injured. Night visual meteorological conditions prevailed at the time, and an instrument flight rules (IFR) flight plan was filed for the 14 Code of Federal Regulations Part 135 cargo flight. The flight originated from Tampa International Airport (TPA), Tampa, Florida, about 5 minutes prior to the accident. The pilot stated that after takeoff, about 800 to 1,000 feet above ground level (agl), he heard a loud bang and the engine rpm increased, followed by an oil pressure decrease. He advised the tower controller at TPA that the flight needed to return but did not declare an emergency. While returning to TPA, the engine rpm decreased and the pilot then declared an emergency with the controller. At 600 feet agl the engine stopped producing power, and the pilot maneuvered the airplane for a forced landing to an athletic field. While on approach the airplane collided with a chain link fence. The airplane came to rest upright, and in a left wing low attitude. The pilot held a commercial pilot certificate for airplane single-engine and multiengine land and instrument airplane. In addition, he held a flight instructor certification for airplane single-engine, airplane multiengine, and instrument airplane. The pilot was issued a first class medical certificate on May 18, 2010, without limitations. He reported 1,330 hours of total flight experience, of which, 10.2 were in the same make and model as the accident airplane. Weather reported at TPA at 2053 included winds from 070 at 8 knots, gusting to 18 knots, 10 miles visibility, few clouds at 6,000 feet, scattered clouds at 25,000 feet, temperature 30 degrees C, dew point 19 degrees C, and an altimeter setting of 30.04 inches of mercury. An inspector from the Federal Aviation Administration (FAA) reported that the airplane sustained substantial damage to the left wing, and fuselage, during the forced landing. The airplane was recovered to the operator's hangar at TPA, for further examination. A post accident examination of the engine revealed that continuity could not be obtained by manual rotation of the crankshaft flange. Both magnetos were removed, rotated by hand, and produced spark on all towers. The spark plugs were removed and visual observation revealed that they exhibited normal wear and their electrodes were light grey in color. Fuel was observed in the fuel lines, fuel manifold, and the fuel pump, and all fuel lines and nozzles were free of obstructions. The oil sump was removed from the engine and metal particles were observed. The oil filter was removed from the engine, and examination of the filter revealed metal shavings and particles. All cylinders were removed, and no abnormalities were noted to their pistons, intake valves, or exhaust valves. The crankcase halves were separated and the main bearing supports, main bearing supports mating surfaces, and tang-lock slots exhibited damage. The No.2 main bearing saddle surfaces of the crankcase exhibited fretting. Portions of the No.2 main bearing was found in the oil sump. The crankshaft was removed from the engine and examined. The crankshaft fractured between the No.2 main journal and the cheek at the aft end of the journal. The No.2 connecting rod did not move freely by hand on the crankshaft connecting rod journal. All other crankshaft connecting rod and main journals appeared intact and exhibited no obvious indication of hard particle passage. The crankshaft, main bearings, connecting rods and bearings, and camshaft were sent to the Safety Board Materials Laboratory for further examination. The examination revealed a fatigue fracture through the crankshaft adjacent to the No.2 main journal. According to the Materials Laboratory Factual Report, "Fatigue features emanated from an origin area at the surface in the fillet between the number 2 journal and the cheek at the aft side of the journal…The origin area of the fracture was smooth and shiny consistent with post-fracture rub damage, however small ratchet lines were visible radiating outward from the fatigue origins at the fillet surface …The number 2 journal and fillet radii at either end of the journal were dull and had circumferential scoring, damage consistent with abnormal bearing contact such as from a shifted bearing. The number 2 main journal was tinted a light gold color and did not display dark discoloration." Examination of the engine logbooks revealed that on December 5, 2007, a magnaflux and ultrasonic inspection of the crankshaft was performed, with "no defects" noted. Then, the engine was overhauled on December 14, 2007, at a tach time of 2069.6 hours. Another entry stated that the No.2 cylinder was removed and replaced on April 13, 2010, at a tach time of 2982.4 hours, about 115.2 hours prior to the accident. The most recent logbook entry was a 100-hour inspection that was performed on May 27, 2010, at a tach time of 3078.3 hours. A FAR Part 135 100-Hour inspection checklist was utilized that stated under the crankcase section to "check bolts and nuts for looseness." At the time of the accident, the tach time was 3097.8.
The total loss of engine power due to inadequate torgue on the crankcase bolts. Contributing to the accident was the inadequate inspection performed 19.5 hours prior to the accident.
Source: NTSB Aviation Accident Database
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