What happened
During a flight from a private grass airstrip, the pilot was conducting a series of airplane rides. During the fifth and final flight, the aircraft experienced an engine failure during the initial climb following takeoff. Witnesses observed the aircraft perform a 180-degree turn back toward the departure runway; however, the plane descended rapidly and impacted the ground while maintaining a level attitude.
The investigation
An on-scene examination of the aircraft revealed the presence of fuel and no obvious mechanical anomalies. The NTSB and a representative from the engine manufacturer performed a subsequent examination. During this process, parts damaged in the crash were replaced and a club propeller was installed. During a test run of the engine, fuel was observed pouring from the carburetor immediately after fuel was added. This behavior was consistent with the needle valve being stuck in the open position due to an obstruction. After tapping the carburetor wall, the obstruction was cleared, and the fuel flow stabilized. The test run was then completed without further issues.
Findings
A teardown examination of the carburetor revealed that debris was present within the carburetor float bowl. This debris was large enough to block either the needle valve or the fuel metering orifice, which led to the engine failure.