What happened
During a repositioning flight to its base airport, the pilot of a multi-engine airplane requested a change in destination without providing a specific reason. While operating in the traffic pattern, radar tracking showed the aircraft entered the left downwind leg and maintained a standard pattern attitude. The aircraft then executed a right turn of approximately 250 degrees to transition into the final approach leg. During this final leg, the aircraft struck a house located in a neighborhood near the airport.
At the time of the impact, radar data indicated a ground speed of roughly 69 knots, which was below the minimum multi-engine approach speed of 95 KIAS and the minimum controllable airspeed of 82 KIAS. Investigation of the propellers showed that both were rotating at a low power setting during the crash. There were zero fatalities reported in the wreckage.
Findings
Post-accident inspections of the right engine revealed a partial loss of power during a controlled test run. Investigators identified damaged o-rings within the throttle and control assembly. The damage to these o-rings was consistent with them being pinched between the fuel inlet surface and the top groove during the installation process. It is believed that the right engine experienced a partial power loss during the final approach, leading the pilot to reduce power to the left engine to prevent a right-hand roll, which ultimately resulted in the aircraft falling below its minimum controllable airspeed.