History of Flight
On October 28, 2013, at approximately 1245 central daylight time, a Piper PA-22-150 (registration N4803A) collided with trees and terrain shortly after departing from Princeton Municipal Airport (PNM), near Princeton, Minnesota. The pilot was the sole occupant and sustained fatal injuries. The aircraft was consumed by a post-impact ground fire. The flight was conducted under 14 CFR Part 91 as a personal flight, destined for an unknown location in North Dakota for hunting. Day visual flight rules (VFR) conditions prevailed, and no VFR flight plan was filed. No witnesses observed the departure or accident. Evidence indicated the airplane departed runway 33 and impacted the ground in a wooded area approximately 600 feet west of the runway's midpoint, where a fire ensued.
Personnel Information
The 51-year-old pilot held a private pilot certificate with airplane single-engine land and instrument ratings. His most recent third-class FAA medical certificate was issued on April 23, 2013, with no limitations. On that application, he reported 625 total flight hours and 85 hours in the previous six months. According to his logbook, he had accumulated 719.9 total hours and 12.8 hours in the 30 days before the accident. The logbook contained a tailwheel endorsement dated October 6, 2012, and a flight review endorsement dated September 12, 2013.
Aircraft Information
The 1956 Piper PA-22-150 (serial number 22-3955) was an externally braced high-wing airplane. A major repair and alteration form dated July 11, 1986, documented installation of a 150-horsepower Lycoming O-320 engine (serial number L-8351-27), driving a fixed-pitch Sensenich M74DM57 propeller (serial number 18889). The most recent annual inspection, including the cabin heater, was performed on February 5, 2013, at 3,283.6 total aircraft hours. On October 27, 2013, a logbook endorsement recorded replacement of the original 6:00-6 main tires with 8:50-6 tires per Supplemental Type Certificate (STC) SA02672CH, and replacement of the tailwheel assembly with a 3200-B bushwheel per STC SA01233SE. At that time, the total aircraft hours were 3,336.5.
Meteorological Information
At 1233, the recorded weather at Princeton Municipal Airport included wind from 040 degrees at 8 knots, visibility 10 statute miles, clear sky, temperature 4°C, dew point -6°C, and altimeter 30.46 inches of mercury.
Wreckage and Impact Information
An FAA inspector examined the accident site. Witness marks in the wooded area indicated the airplane was traveling west. The wreckage came to rest with the nose at approximately a 75-degree heading. All control surfaces were intact, and control system continuity was established. On-scene examination of the engine and propeller showed indications consistent with the propeller being driven at impact, but the power level could not be determined. No mechanical anomalies were discovered.
Medical and Pathological Information
An autopsy performed by the Mille Lacs County Medical Examiner's Office listed blunt force and thermal injuries as the cause of death. The FAA Civil Aerospace Medical Institute's Final Forensic Toxicology Accident Report detected 19% carbon monoxide in the pilot's blood.
Additional Information
A review of STC SA02672CH revealed that the FAA's approval for the 8:50-6 main tire installation did not include a flight test; it was based on prior testing with larger 26-inch tires and an 82-inch propeller, for which no performance changes to the pilot operating handbook were published. No flight test was conducted for the 8:50-6 tires with the aircraft's certificated 74-inch propeller. Additionally, the FAA pamphlet "Carbon Monoxide: A Deadly Menace" notes that carboxyhemoglobin levels above 10% can cause symptoms such as headache; the pilot's 19% level is elevated above typical non-smoker baseline.