Flight Design Gmbh CTSW N535CT accident near Haskell, Oklahoma

Probable cause

The loss of engine power for reasons that could not be determined because a postaccident engine examination and test run did not reveal any evidence of preimpact malfunctions or failures that would have precluded normal operation.

NTSB analysis

The sport pilot completed a preflight inspection of the airplane and noted that it had about 28 gallons of automotive fuel; he conducted a cross-country flight with no anomalies noted. After starting the engine before takeoff for the return flight, the pilot noticed that the engine gauges were normal but that the charging system had an inadequate output, so he shut down the engine. After consulting a mechanic, he restarted the engine and noted normal engine and charging indications. During the takeoff climb, about 500 to 600 ft above ground level, the engine starting "sputtering" and continued to run but the airplane did not maintain altitude. The choke was off, and the pilot applied various throttle settings to no avail. The pilot performed a forced landing to a field, and the airplane came to rest inverted.

Postaccident examination of the airplane's fuel system was satisfactory and did not reveal any contamination. Further, examination of the engine revealed that the engine's left and right carburetor float bowls contained clean fuel. During a test run of the engine, the engine was started and run at idle before running up to power. The postaccident engine examination and test run did not reveal any evidence of preimpact malfunctions or failures that would have precluded normal operation.

Weather conditions at the time of the accident were conducive to the accumulation of serious carburetor icing at glide power settings; however, the airplane was fueled with automotive fuel, which may have a different carburetor icing range than that depicted in Federal Aviation Administration guidance for aviation fuel. Additionally, the airplane was at takeoff power and not glide/idle power when the power loss occurred. Thus, it is not likely that the formation of serious carburetor icing occurred. A reason for the loss of engine power could not be determined.

Text from the NTSB. Open the NTSB docket for CEN15LA258 for the full record.