What happened
During a night flight conducted under instrument meteorological conditions, the pilot was executing a non-precision approach. While performing the procedure turn, the aircraft experienced a significant loss of airspeed that approached the stall threshold before eventually recovering to standard approach speeds. Following the descent from the final approach fix, the aircraft's rate of descent leveled off for approximately 30 seconds before resuming a descent at roughly 1,300 feet per minute.
As the flight continued, the aircraft decelerated further. At an altitude of 500 feet mean sea level, the airspeed had dropped to approximately 85 knots, which was only 7 knots above the calculated stall speed for the flaps 20° configuration. The final recorded data indicated the aircraft was at 460 feet mean sea level and 750 feet from the site of the accident. The aircraft subsequently struck a private residence, which triggered a post-crash fire that completely destroyed the airframe.
Findings
Investigation of the wreckage revealed that the impact signatures were consistent with a low-energy event. A mechanical inspection of the engines and airframe showed no evidence of pre-impact malfunctions that would have prevented the aircraft from operating normally. Furthermore, evidence from the propellers and engines indicated that both engines were producing power at the time of impact. Toxicological analysis of the pilot showed subtherapeutic levels of eszopiclone, which was not considered a contributing factor. The investigation concluded that the accident was caused by an inadvertent aerodynamic stall from which the pilot could not recover.