Incident Overview
On May 10, 2009, about 1310 Pacific daylight time, a Cessna U206E, registration N1457M, experienced a total loss of engine power while cruising approximately 5 miles north of Oroville, California. The private pilot made a forced landing in an open field. During the landing roll over uneven terrain, the airplane's nose gear broke off, the firewall was bent, and the airplane sustained substantial damage. The pilot, who co-owned the airplane, was not injured. The flight was conducted under 14 CFR Part 91 as a personal flight, originating from Marysville, California, about 1230. Visual meteorological conditions prevailed, and no flight plan was filed.
Pilot's Account
The pilot reported that at departure the fuel tanks contained a total of 55 gallons of 100 LL fuel. After takeoff, he performed two uneventful touch-and-go landings, then climbed to a cruise altitude of 2,600 feet mean sea level. While cruising, the engine suddenly "died, as if the [ignition] key were shut off." Power returned momentarily without action, then the engine died completely. The pilot switched fuel tanks and activated the electric fuel pump. The propeller continued to windmill. Due to low altitude, he focused on the forced landing. Restart attempts were unsuccessful, and he landed on rough terrain at about 1,100 feet msl.
Post-Accident Examination
Airplane recovery personnel found evidence of fuel in all fuel tanks. The aircraft was examined by FAA personnel, who observed minimal propeller blade damage consistent with low or no engine power at impact. Control continuity between cockpit engine controls and the engine was confirmed. No anomalies were noted with magnetos, spark plugs, cylinders, or internal engine components during crankshaft rotation. Fuel system integrity between wings and engine was confirmed; fuel vents and bladder tanks had no blockages.
An FAA principal maintenance inspector test-ran the engine. The electric fuel pump operated normally, and the engine started and ran for 12 minutes with no anomalies. The inspector found no evidence indicating why the reported power loss occurred.
Engine Data Recorder Analysis
The airplane was equipped with a J.P. Instruments EDM-800 engine data management system. After the FAA engine test run, the unit was removed and its memory downloaded by JPI personnel under Safety Board supervision. The instrument appeared undamaged and the data file was not corrupt. The downloaded data from the accident flight included a graph of time, exhaust gas temperature (EGT), fuel flow, and RPM. Selected data points:
- At 2117:54: EGT 1378°F, Fuel Flow 17.6 gph, RPM 2465
- At 2124:12: EGT 1354°F, Fuel Flow 16.2 gph, RPM 2345 (EGT rose to 1417 at 2124:24)
- At 2124:24: Peak EGT 1417°F, Fuel Flow 11.2 gph, RPM 2339
- At 2124:30: EGT 1007°F, Fuel Flow 0.9 gph, RPM 2130
- At 2124:36: EGT 572°F, Fuel Flow 0.0 gph, RPM 1937
- At 2125:42: EGT 241°F, Fuel Flow 0.0 gph, RPM 0
The data show a sharp drop in EGT, fuel flow, and RPM coinciding with the power loss. The JPI Pilot's Guide notes that retarding the mixture causes EGT to rise to a peak then drop as mixture is further leaned.
Conclusion
Despite thorough examination and engine test runs, no mechanical or system anomaly was identified that could explain the total loss of engine power.