Accident Overview
During a positioning flight, a twin-engine medical transport airplane experienced a loss of power in one engine. The pilot reported the issue to air traffic control and requested landing. Radar data showed the airplane in a descent and executing multiple right-hand turns. The pilot's final transmission indicated one engine was not producing power. The last radar return placed the airplane at 200 feet above mean sea level, near the accident site, approximately 0.6 miles west of the approach end of the runway.
Performance and Configuration
Performance calculations indicated that with the landing gear down and flaps fully deployed—as found at the impact site—level flight was not possible with one engine inoperative. The documented minimum controllable airspeed (VMC) for this airplane is 68 knots. Radar track data showed the average ground speed decreasing from 134 knots to 76 knots before impact. The zero bank angle stall speed ranged from 78 knots in a cruise configuration to 70 knots with gear and flaps down. A sound spectrum study revealed one engine operating at 2,630 rpm and the other at 1,320 rpm. Propeller damage was consistent with the right engine producing higher power than the left engine at impact; both propellers were at or near the low pitch stops and not feathered. Examination of both engines found no evidence of mechanical malfunction.
Training and Procedures
The pilot had received training and demonstrated proficiency in slow flight and single-engine landings. However, flight at minimum controllable airspeed with one engine inoperative was not practiced during training. The operator's training manual included an objective to reduce drag during single-engine training but lacked a specific procedure to achieve this. The ground training syllabus did not address engine-out airplane configuration performance as a dedicated topic. The operator's emergency procedures checklist and the manufacturer's information manual clearly described the performance penalties of configuring the airplane with an inoperative engine, an unfeathered propeller, landing gear down, or flaps deployed. The engine failure during flight procedure and the engine inoperative go-around checklist, if followed, would have configured the airplane for level single-engine flight by feathering the propeller, raising the flaps, and retracting the landing gear.
Probable Cause
The investigation determined that the accident resulted from the pilot's failure to execute published emergency procedures for single-engine flight configuration, which would have allowed maintenance of VMC and level flight. The pilot's failure to maintain VMC led to a stall and subsequent VMC roll at low altitude. Contributing factors included the operator's inadequate pilot training in the single-engine flight regime and an undetermined loss of power from the left engine.