What happened
The pilot reported that prior to takeoff, he encountered difficulty getting the engine to develop adequate power. He consulted a mechanic who identified conditions favorable for carburetor icing and advised applying carburetor heat. The pilot followed this recommendation, noting an improvement in engine performance, which led him to take off to test the aircraft's operation in flight.
During the initial phase of flight, the pilot circled several times with the carburetor heat engaged. He then turned the heat off, causing the engine RPM to increase briefly before the engine sputtered and lost power. Although the pilot reapplied the carburetor heat, the engine did not respond fully. The aircraft sustained damage upon landing in a spruce-covered, swampy area.
The investigation
The investigation focused on the mechanical state of the engine and the reported sequence of events regarding carburetor ice formation and removal. The pilot's account indicated that applying heat initially helped, but removing it caused immediate power loss that could not be fully recovered by reapplying heat.
Findings
- Carburetor icing was determined to be the primary factor in the engine failure.
- The pilot successfully identified the condition and applied the correct initial remedy.
- However, the removal of carburetor heat resulted in ice accumulation that obstructed airflow, leading to a complete loss of power.
- The inability to recover full power despite reapplying heat suggests severe icing or ice blockage.
Safety message
This incident highlights the critical nature of managing carburetor ice. While applying heat can mitigate initial symptoms, removing it too early or allowing ice to build up significantly can lead to irreversible power loss. Pilots must monitor engine performance closely and maintain heat application until conditions are confirmed safe.