What happened
During the pre-flight inspection, the pilot noted an excessive magneto drop while running up the engine. To address this condition, he adjusted the mixture control to a leaner setting. However, there is no record of the pilot returning the mixture control to the full rich position prior to initiating the takeoff roll.
After becoming airborne, the engine performance began to degrade gradually. The power loss continued until the engine eventually quit completely. With no power available, the pilot was forced to execute an emergency landing in unsuitable terrain. During this forced landing, the aircraft struck a tree and subsequently hit a building.
The investigation
The investigation focused on the pilot's actions during the pre-flight phase and the subsequent flight. Key findings included:
- The pilot admitted to leaning the mixture to correct an excessive magneto drop.
- The pilot did not state that he placed the mixture control to full rich before takeoff.
- The engine lost power gradually after takeoff, indicating a fuel delivery issue rather than an immediate mechanical failure.
Findings
The primary factor leading to the accident was the improper management of the engine mixture. By leaning the mixture to correct a magneto drop and failing to reset it to full rich, the engine received an insufficient fuel-air ratio for takeoff power. This resulted in a gradual loss of power that left the pilot with no options other than a forced landing.
Safety message
Pilots must ensure that all pre-flight checks are completed correctly. If adjustments are made to correct engine irregularities, such as magneto drop, the controls must be returned to their proper settings before flight operations begin.