What happened
The aircraft encountered an unexpected loss of engine power while climbing at an altitude of approximately 300 feet above ground level, immediately following takeoff. With no option to return to the departure airport, the pilot executed a forced landing in a nearby plowed field. The landing was conducted with the main landing gear retracted or not extended, resulting in a wheels-up touchdown.
The investigation
Post-accident examination of the aircraft revealed specific mechanical anomalies within the engine and induction system. A seal surrounding the carburetor air mixing box had become detached from its mounting position. Additionally, inspection of the turbocharger assembly showed that an internal oil seal was significantly worn. Despite these findings, the engine was tested on the ground after the incident. A run-up performed post-accident indicated that the engine operated normally during static testing, suggesting the failure was likely intermittent or dependent on specific flight conditions rather than a complete mechanical seizure.
Findings
The sequence of events points to a critical failure in the engine's induction or turbocharging system during the initial climb phase. The dislodged seal around the carburetor air mixing box likely allowed unmetered air into the engine or disrupted the fuel-air mixture, leading to the power loss. Concurrently, the worn oil seal in the turbocharger may have contributed to reduced efficiency or oil leakage that exacerbated the performance issue. The fact that the engine ran normally during a subsequent ground run-up suggests that the components had not failed catastrophically but were compromised enough to fail under the high-load conditions of takeoff and climb.
Safety message
Regular inspection of turbocharger seals and carburetor air mixing box seals is critical for maintaining engine performance. Pilots should be aware that intermittent power loss during high-power phases of flight can indicate subtle mechanical issues that may not manifest during ground run-ups.