Accident Overview
On June 17, 2018, at approximately 0830 central daylight time, a Cessna T210F airplane, registration N6107R, nosed over during an off-airport forced landing in Desdemona, Texas. The private pilot and one passenger received minor injuries, while a second passenger was seriously injured. The airplane sustained substantial damage. The flight was operated under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the accident site, and no flight plan had been filed.
The flight departed Dublin Municipal Airport (9F0) in Dublin, Texas, around 0820, en route to Gregory M. Simmons Memorial Airport (GZN) in Cisco, Texas.
Pilot Report
The pilot stated that, during cruise flight at 2,400 ft above mean sea level, the engine began running rough. He leaned the fuel mixture, and the roughness subsided. A few minutes later, the engine again ran rough. Switching fuel tanks did not change engine operation. Shortly thereafter, the engine lost power. The pilot performed a forced landing in a soft, sandy field, and the airplane nosed over.
Postaccident Engine Examination
Initial examination revealed the engine remained attached to the airframe, with various wires, cables, and hoses still connected. The top spark plugs exhibited normal wear but were dark in color and oily. Boroscopic inspection of the cylinders showed no abnormalities.
The engine was then removed from the airframe and shipped to the manufacturer for a test run.
Engine Testing
During the initial test run, the engine started without hesitation and operated at 1,200 rpm and 1,600 rpm with the fuel pump mixture control at full. After two minutes, engine power began to oscillate. The engine was shut down, and the mixture control was adjusted to about half its original setting. Restarted, the engine ran for 1 minute and 20 seconds before power again decreased, with fuel pressure reaching 40 psi—8 psi above the maximum unmetered flow limit of 32 psi.
The fuel pump was removed and bench-tested. At full power (2,700 rpm), fuel flow was about 170 pounds per hour with a fuel pressure of 92 psi. According to the engine manufacturer, the expected pressure range was 29 to 32 psi. The adjustment screw was set to 30 psi, and the pump was reinstalled.
A subsequent test run saw the engine started and run to 1,600 rpm, which slowly dropped to 1,498 rpm. Power was increased to 2,552 rpm, and fuel pressure stabilized at 30.18 psi with smooth engine operation.
During the initial engine run, excessive manifold pressure was observed. During the second run, the turbocharger controller was adjusted to maintain normal manifold pressures.