Accident Sequence
During a descent from 10,500 feet, the pilot observed a drop in manifold pressure to 18 inches. Deciding to land at a nearby airport, the pilot began troubleshooting the issue. Activating the boost pump resulted in further engine power loss, and the cockpit began to fill with smoke. The pilot then secured the engine and turned off the electrical system.
With the engine off, the pilot initiated a power-off descent over the airport and manually extended the landing gear. Believing the aircraft was too high, the pilot turned the battery back on to lower the flaps. However, restoring electrical power caused the landing gear to retract to the up position. The pilot again lowered the landing gear.
Unable to reach the runway, the pilot attempted to restart the engine during the final approach but did not have sufficient time. The aircraft subsequently impacted an upslope approximately 300 feet short of the runway and crashed.
Investigation Findings
Examination of the turbocharger revealed that the turbine shaft had failed due to multiple fatigue cracks. Approximately 125 flight hours before the failure, the turbine shaft had been reworked through grinding and chromium plating. This rework was not performed in accordance with the manufacturer's specifications. Additionally, the Pilot's Operating Handbook (POH) did not address turbocharger malfunction procedures.