Accident Details
On July 31, 2010, at approximately 0910 mountain daylight time, a Cessna 177B airplane, registration N35296, sustained substantial damage following a partial loss of engine power during initial climb. The forced landing occurred at Rawlins Municipal Airport (RWL), Rawlins, Wyoming. The certificated airline transport pilot and sole passenger were not injured. Visual meteorological conditions prevailed, and the flight was operated under 14 Code of Federal Regulations Part 91. No flight plan was filed. The flight was originating at the time, with Scottsbluff, Nebraska as the planned destination.
Pilot Report
The pilot stated that before departure, he noticed a sign at the fixed base operator indicating that runway 04 had an uphill gradient with rising terrain at the end. The windsock favored runway 04. At the end of runway 04, he performed run-up and preflight checks, which appeared normal. The pilot reported that he failed to lean the fuel mixture before takeoff. He taxied onto runway 04 and applied full power. Engine revolutions per minute (RPM) and manifold pressure indicated 2,700 RPM and 23 inches of mercury (Hg), with normal oil temperature and pressure. The airplane accelerated slowly, which he attributed to the 6,800-foot mean sea level (msl) elevation. After rotation at normal speed and climbing to about 50 feet above ground level, the aircraft vibration and sound changed. RPM dropped to 2,500 and the airplane lost altitude. The pilot cut power and landed on the runway overrun. The airplane struck a rock with its left main landing gear before stopping. Substantial damage occurred to the elevator.
Post-accident Examination
At the request of the NTSB investigator-in-charge, a certified FAA airframe and powerplant mechanic examined the engine. Visual inspection of spark plugs revealed that cylinder #4 top and bottom spark plugs were carbon fouled, and all spark plugs showed carbon fouling. All cylinders were borescoped with no anomalies. Intake and exhaust rocker arms moved normally. While rotating the crankshaft, spark was verified at all ignition harness leads, the carburetor's accelerator pump expelled fuel when actuated, and engine timing checked normal. During the first engine run, it ran rough, but after cleaning cylinder #4 spark plugs, the engine ran normally at all power settings. The mechanic concluded that the engine ran too rich, preventing proper operation.
Weather Conditions
At 0853, the weather reporting facility at RWL reported wind variable at 3 knots, visibility 10 miles, temperature 21°C, dew point 10°C, and altimeter setting 30.21 inches of mercury. Density altitude at the time was calculated at 8,895 feet.
Checklist Information
The Cessna 177B Before Takeoff checklist, item 6, states: Mixture – RICH (below 3000 ft.). The Takeoff checklist, under Maximum Performance Takeoff, item 5, states: Mixture – LEAN for maximum power (above 3000 feet elevation). The airport elevation was 6,813 feet msl.