Approach and Engine Issue
The pilot executed a gliding approach from 3,500 feet MSL, with the engine power set between 1,500 and 1,700 RPM and carburetor heat on. The pilot reported to the investigator-in-charge that while descending through the first 3,000 feet, he did not clear the engine. The pilot recounted that the RPM began 'falling off,' and when he increased the throttle, the RPM did not rise.
Forced Landing and Obstacle
Due to the loss of engine power, the pilot performed a forced landing. However, because of 'dusky conditions and slight haze,' the pilot did not see a levee wall. During the landing flare, the right wing impacted the levee.
Environmental Conditions
At the time of the accident, a temperature inversion was present. Ground level humidity was 22%, while humidity at 5,000 feet was 49%.
Guidance and Engine Testing
The FAA Flight Training Handbook, in the section 'Descents (Maximum Distance Glides),' states that during power-off descents, the engine should be cleared periodically to prevent excessive cooling and fouling. The engine was later test run on the airframe. According to the manufacturer, who performed the test run, the engine 'startup was immediate, and the engine ran smoothly.'