Accident Overview
On August 7, 2020, about 1145 mountain daylight time, a Cessna T210M airplane, registration N2245S, was substantially damaged during an accident near Hanna, Utah. The private pilot and one passenger sustained serious injuries, while four passengers sustained minor injuries. The flight was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
Flight History
Flight track data indicated the airplane departed from Roosevelt Municipal Airport (74V), Roosevelt, Utah, and climbed northwest over mountainous terrain to an altitude of 12,896 ft mean sea level (msl) during the first 20 minutes of the 25-minute flight. The track then showed a decrease in altitude as the airplane approached a large canyon.
The pilot reported a partial loss of engine power during a turn over mountainous terrain. He did not describe any actions taken to address the partial power loss. The pilot stated he decided to fly down the canyon as the propeller continued to windmill, initiating a forced landing to an open field. The field was near the shoreline of a lake at an elevation of 8,100 ft msl, and the accident site was south and down the canyon about 7 1/2 miles. Flight track data ended shortly after the airplane reached the canyon.
Onboard Video Evidence
An onboard video recorded by the front-seat passenger showed that shortly after engine start, the fuel selector handle was moved from the right tank to the left tank. Fuel quantity indicators showed about 19 gallons for the left tank and about 12 gallons for the right tank. About 20 minutes into the flight, over the lake, the engine rpm increased momentarily and then fluctuated at a lower rpm, slowly decreasing until the end of the video. The pilot prepared for a forced landing by extending the landing gear and announcing intentions. As the airplane approached the shoreline, the stall warning horn was heard intermittently before the airplane banked left and impacted terrain. A screenshot at impact showed the rpm gauge indicating about 1,600 rpm, manifold pressure at 19 inches of mercury, and fuel flow gauge needle off the scale. The throttle, propeller, and mixture levers were fully forward.
Pilot and Maintenance Information
The pilot received his private pilot checkride endorsement on May 27, 2016, and had about 250 hours of total flight experience. His last biannual flight review was on June 16, 2020. At the time of the accident, his third-class medical certificate was overdue by about 6 months.
Airplane maintenance records showed that on June 12, 2020, the engine had accumulated 947 hours since overhaul. A top overhaul had been completed about 30 flight hours before the accident.
Engine Data Analysis
Engine data downloaded from an onboard instrument revealed that fuel flow decreased from 20 to about 16 gallons per hour, remained at 16 gph for about 1 minute, rose to about 18 gph, then dropped to near zero. Seconds later, engine rpm increased momentarily to just above 2,500 rpm before slowly decreasing to about 1,900 rpm. Calculations indicated about 8 1/2 gallons of fuel were consumed during the flight.
Postaccident Examination
Examination of the accident site showed the forward fuselage and cabin area crushed upward, the engine partially separated from the firewall, and both wings buckled near the tips. Postaccident examination of the engine and airframe revealed no evidence of preimpact malfunctions or anomalies.
Sound spectrum analysis of the onboard video could not determine if the engine speed decrease was due to lack of cylinder combustion or if the engine continued operating at reduced speed.