History of Flight
On May 31, 2010, about 1645 Pacific daylight time, a Piper PA-20, registration N7013K, collided with terrain in a rice field near Nelson, California. The pilot operated the airplane under 14 CFR Part 91. The certificated private pilot and two passengers sustained serious injuries. The airplane sustained substantial damage to the forward fuselage and both wings. The local personal flight departed from a private strip owned by PM Dusters Flying Service in Chico, California, about 1600. Visual meteorological conditions prevailed, and no flight plan was filed.
The airplane came to rest inverted and semi-submerged in a 12-inch-deep water-logged rice field, about 5 miles southwest of the PM Dusters airstrip. A ground disruption was observed in the mud bed about 20 feet south of the main wreckage; the left main landing gear was located within the disruption.
Due to injuries, the pilot and passengers could not recall the immediate events leading up to impact. One passenger in an aft seat recalled departing from the airplane’s home base at PM Dusters earlier in the day, flying locally at about 700-800 feet above ground level, and landing at a dirt airstrip. During the subsequent departure, the airplane began a right turn; his next recollection was being upside down on the ground. He stated the airplane was performing normally and the engine was running before the accident.
The accident occurred within the vicinity of multiple dirt airstrips, so the exact departure location could not be determined.
Personnel Information
The 19-year-old pilot and both passengers, aged 19 and 16, were non-pilot employees of PM Dusters. According to family members, the pilot had purchased the airplane earlier that year to build flight time for a commercial pilot's license, with the intention of becoming a crop duster.
The pilot reported a total flight time of 88.8 hours, with 46.9 hours as pilot-in-command, and 35.4 hours in the accident airplane type. FAA records showed he held a private pilot certificate with single-engine land rating, issued March 11, 2010, and a third-class medical certificate issued August 2009, with no limitations.
Aircraft Information
The Piper PA-20 was equipped with a Textron Lycoming O-320 engine (serial number 2959-27). Maintenance records indicated an annual inspection on September 19, 2009, at a total airframe time of 3,355.5 hours; the tachometer at the accident site indicated 1,879.2 hours.
Wreckage and Impact Information
The inverted fuselage rested on a south heading, with crush damage from the firewall through the center cabin, oriented at a 45-degree angle relative to the longitudinal axis, indicating a nose-down collision. The left wing sustained crush and fragmentation damage along its entire length. The right wing remained relatively intact, bent about 30 degrees aft, and attached at the lift spars and wing root. The right main landing gear was undamaged and attached. The tail cone had torsional damage midspan; the empennage remained attached and appeared undamaged.
An FAA inspector observed a sheen in the water with an odor consistent with aviation gasoline.
Tests and Research
The engine and airframe were examined by the NTSB, FAA, and Piper Aircraft.
Airframe: Rudder and elevator control cables were continuous from pilot controls to control surface horns. Right wing aileron cables were continuous and cut during recovery. The aileron balance cable had separated midspan with broomstraw failure features consistent with overload. Left wing aileron control continuity was confirmed to a bellcrank. Impact damage prevented determination of flap positions. The fuel selector valve was set to the right tank. Damage precluded confirmation of fuel system continuity. The elevator trim actuator exhibited 6 exposed threads, which a Piper representative stated was consistent with a slight nose-up trim (neutral is 8 threads).
Engine: External examination showed no holes or perforations in the case. Mounts and support structure were bent inward. The exhaust system had ductile bending and crushing; the number 2 exhaust manifold separated at the cylinder mounting flange. The carburetor was fractured into three sections; the brass float had crush damage. Throttle, mixture, and carburetor heat cables were attached. The gascolator was fragmented; the screen was free of debris. Ignition harnesses were attached from magnetos to spark plugs. The flywheel separated from the crankshaft due to impact, preventing magneto timing confirmation. Both magnetos were removed for testing; left magneto impulse couplings operated with spring-back but no sparks observed; right magneto produced no sparks. Disassembly revealed water contamination from post-accident submersion, with corrosion. Points, cam lobes, and gear teeth were intact. Bottom spark plugs showed normal gray coloration; top plugs had oil film and water consistent with inversion and submersion. Hand rotation of the engine via propeller confirmed mechanical continuity; thumb compression was achieved on all cylinders. Borescope inspection showed no foreign object damage or piston-to-valve contact. The crankcase contained 4 quarts of translucent oil; rocker boxes were oil-wetted. The two-bladed propeller remained attached to the bent crankshaft flange; both blades had leading edge nicks; one blade was bent forward; the spinner was compressed into a bowl shape. No evidence of pre-mishap mechanical malfunctions was found in the engine or airframe.