History of Flight
On July 17, 2011, at about 1500 Alaska daylight time, a Piper PA-12 airplane, registered as N92770, sustained substantial damage when it collided with tree-covered terrain following a loss of engine power after takeoff from a private airstrip near Delta Junction, Alaska. The sole occupant, a commercial pilot, was fatally injured. The flight was conducted as a visual flight rules (VFR) personal flight under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The intended destination was Fairbanks International Airport, Fairbanks, Alaska.
Two witnesses, both commercial pilots, reported hearing light popping sounds and the engine sounding quieter than normal as the airplane flew overhead. Approximately 200 to 300 feet above ground, the engine became quiet. The pilot made a left turn, followed by a nose and left wing low descent. The airplane struck terrain about 250 yards from the departure end of the airstrip.
Personnel Information
The pilot held a commercial pilot certificate with ratings for airplane single and multiengine land, rotorcraft, instrument airplane, and instrument helicopter, and also served as a helicopter pilot for the United States Army. His most recent third-class medical certificate was issued on June 11, 2010, with no limitations. No personal flight records were found; according to his June 11, 2010, medical certificate application, he reported a total flight time of 230 hours, with zero hours in the preceding six months.
Aircraft Information
The accident aircraft was a Piper PA-12 equipped with a Lycoming O-320 engine rated at 150 horsepower, installed on April 17, 1991. The engine had accumulated 2,636.5 service hours, including 636.5 hours since its last major overhaul on August 15, 2001. The aircraft was fitted with a two-blade McCauley propeller. The airframe had 4,351 service hours, and the last annual inspection was performed on February 2, 2011, at 4,325.5 service hours.
Meteorological Information
The nearest official weather observation station, Allen Army Airfield (PABI) in Delta Junction, located 4 nautical miles southwest of the accident site, reported at 1453: wind 080 degrees true at 3 knots, visibility 10 statute miles, few clouds at 4,000 feet, scattered at 6,000 feet, temperature 65°F, dew point 47°F, and altimeter 29.74 inHg.
Wreckage and Impact Information
On July 18, NTSB and FAA investigators examined the aircraft at the accident site. The airplane had impacted level, wooded terrain adjacent to the airstrip and came to rest upright in a nose-low attitude on toppled and broken trees, with the tail suspended against a tree by the right vertical stabilizer. All control surfaces were present, and flight control continuity was confirmed. Both wings exhibited spanwise leading edge crushing; a portion of the right wing was separated and lodged in a tree. The wing flaps were extended. Approximately 10 gallons of fuel were drained from the right wing fuel tank; no fuel was found in the left tank, but the fuel gascolator valve was open due to impact damage, with fuel observed on the ground beneath it. No fuel was in the gascolator bowl, and the screen was free of contamination. Both fuel tank selectors were in the ON position. Fuel was present in the carburetor float bowl, and no water was detected.
The propeller had separated at the crankshaft flange; one blade was slightly bent aft, the other undamaged. The engine remained attached to the airframe and was relatively free of damage except for a bent crankshaft flange and some exhaust piping deformation. The throttle and mixture controls were full forward, the master switch was turned off by first responders, and the carburetor heat was off. The pilot's seat frame, bolted to the fuselage via four non-adjustable tabs, had broken at or near three of the four connection points during the accident, shifting the seat forward about 6 inches; all fractures were consistent with overload. The empennage was largely undamaged except for the right elevator, which was resting against a tree with crushed and upward-bent trailing edge. Both main landing gear were bent upward and aft, showing right-side loading.
Medical and Pathological Information
The pilot received on-site medical attention and was transported to a local clinic, where he was initially alert but had no memory of the accident. His condition rapidly deteriorated; he required life support and died during air transport to Anchorage, the nearest trauma center. A postmortem examination attributed the cause of death to multiple blunt force injuries. Toxicological tests were negative for carbon monoxide, cyanide, and ethanol. Etomidate was detected in blood and urine; Midazolam (0.048 µg/ml) and Propofol were detected in urine—all were used for medical sedation.
Tests and Research
The aircraft was recovered to Alaska Claims Services, Inc., in Wasilla. On August 12, the NTSB examined the airframe and found no preaccident anomalies. The fuel system was unobstructed from both tanks to the engine compartment, and the fuel vent system was clear. On August 18, an engine teardown inspection at Alaska Aircraft Engines in Anchorage revealed no anomalies, contamination, or evidence of malfunction in any components, including magnetos, ignition harness, induction system, spark plugs, oil pump, oil cooler, oil filter, and internal parts (cylinders, pistons, valve train, crankshaft).
According to a carburetor icing probability chart, conditions at the time were conducive to serious carburetor icing at glide power settings. The pilot taxied approximately 0.25 miles from the parking area to the departure end of the airstrip. The accident site was bordered on the east by a dirt road about 20 feet wide with additional clear space; about 300 yards north was a large open field.