Flight Details
On April 4, 2010, at 1035 Pacific daylight time, a Cessna P210N (registration N3599P) sustained substantial damage following a loss of engine power and subsequent forced landing near Leavenworth, Washington. The airplane was registered to Centurion Flyers, LLC, and operated by the pilot under 14 CFR Part 91. The commercial pilot, the sole occupant, was not injured. The flight departed Everett, Washington, at 1000 with a planned destination of Spokane, Washington. Visual meteorological conditions prevailed at the departure and destination airports. The pilot filed an instrument flight rules flight plan but elected not to activate it due to VMC.
During a telephone conversation with the NTSB investigator-in-charge, the pilot reported that the airplane was in cruise at 11,500 feet when the engine suddenly quit without warning. Attempts to restart were unsuccessful, and the pilot began an emergency descent over mountainous terrain with an overcast layer with cloud tops estimated at 9,500 feet MSL. The airplane entered instrument meteorological conditions shortly after starting the descent. It descended out of the cloud layer approximately 2,000 feet above ground level and 3.9 miles from a dirt airstrip the pilot was attempting to reach. Unable to make the airstrip, the pilot maneuvered toward a nearby open field, lowered the gear and flaps, and slipped the airplane to reach the field. Just before touchdown, the airplane collided with a fencepost, shearing off the nose landing gear. Upon touchdown on muddy, soft terrain, the main gear caught, the airplane spun right approximately 60 degrees, and the right wing impacted the ground.
Engine Examination
An FAA inspector examined the airplane. The accident airplane (serial no. 00039) was equipped with a Teledyne Continental Motors TSIO 520 P engine and a three-bladed constant-speed propeller. The owner indicated the engine had accumulated 726 total flight hours since new. The most recent annual inspection of the airplane, engine, and propeller was completed on June 16, 2009. At the time of the accident, the airplane had accumulated 4,175 total flight hours, 152 hours since the annual inspection.
Disassembly of the engine revealed extensive mechanical damage to the number two cylinder combustion chamber and piston assembly. The exhaust valve seat insert was missing, and fragments were later found in the oil sump. The exhaust valve head had separated from the valve stem. The intake valve head had approximately 50 percent of its material separated. The cylinder skirt was intact and undamaged. The cylinder overhead components (rocker arms, guides, springs, retainers, and shafts) were lubricated and undamaged. The piston was mechanically fragmented, with most fragments located in the oil sump. Two large fragments of the piston were found lodged between the crankshaft and crankcase. The crankshaft and counterweight assembly exhibited mechanical damage. The connecting rod exhibited mechanical damage with a bent I-beam; its cap remained secure and showed damage at its base, but nuts and bolts were intact and secure. The rear set of counterweight assemblies had mechanical damage but were intact with free unrestricted movement.
The fracture surfaces on the exhaust valve, intake valve, and exhaust valve seat were damaged such that the mode of fracture could not be definitively determined. Hardness testing indicated the components were within manufacturer’s specifications. The sequence of the fractured components could not be determined.
Damage
Examination by an FAA inspector revealed substantial damage to the right wing and forward undercarriage.