Amateur-built CH-750 N632DR accident near Winchester, California

Probable cause

A total loss of engine power during descent for reasons that could not be determined because postaccident examination did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The builder/owner/pilot of the kitplane had selected and installed a modified Chevrolet Corvair engine as the airplane's powerplant and was in the early stages of the test flight program. The engine had accumulated a total of about 3 flight hours before the accident flight, and the fuel quantity gauges were not yet operative. About 45 minutes into the flight, the engine experienced a complete loss of power during a reduced-power descent toward the home airport, and the pilot was unable to restart the engine. In the resulting off-airport forced landing, the airplane came to rest inverted. First responders observed that fuel was leaking from the tanks. Examination of the airplane and the ground underneath the airplane a few hours after the accident revealed only trace amounts of fuel. Residual fuel from the source used to fuel the airplane for the accident flight tested negative for both water and ethanol, and the fuel strainers were free of obstructions. About 1 month after the accident, the chief engine designer at the engine modification company examined and prepared the engine for a test run. The engine started and performed normally through various power settings. The designer concluded that the engine failure was due to fuel exhaustion. Total fuel capacity was about 24 gallons, and the pilot estimated that he departed on the flight with about 13 gallons. According to the designer, the engine would have consumed between about 7 and 11 gallons per hour between the cruise- and full-power settings.

The pilot stated that during the descent in which he experienced the engine failure, the engine rpm was no lower than 2,400 rpm; therefore, he did not use carburetor heat. Correlation of ambient temperature and dew point values indicated that the airplane was operating in a region that corresponded to "Serious Icing (Glide Power)," near the boundary of the region denoted as "Serious Icing (Cruise Power)." Available evidence was insufficient to conclusively determine whether the engine power loss was due to fuel exhaustion or carburetor icing.

Text from the NTSB. Open the NTSB docket for WPR11LA199 for the full record.