Accident Scenario
The aircraft was conducting circuits from Entebbe Airport for a DHC-4 Type Rating (Night) Flight Examination. The cadet pilot occupied the left seat and the check captain sat in the right seat; no passengers were on board. The first circuit, which involved a simulated hydraulic failure, was completed without incident. On the second circuit, the starboard engine was intentionally feathered, and the aircraft made a landing approach on one engine. Just prior to touchdown, a sudden increase in engine power caused the aircraft to yaw and roll steeply toward the starboard side. The aircraft then began skidding on its starboard wheel and wing tip, sliding across the runway and over the adjoining grass strip toward the aerodrome boundary. Approximately 220 meters further down, it crossed a drainage ditch and crashed through a barbed wire fence along the aerodrome perimeter. The fuselage broke in half during the crash, and the wreckage came to rest about 15 meters beyond the aerodrome perimeter.
Injuries and Damage
The check captain suffered severe back injuries. The cadet pilot sustained no injuries. The aircraft was substantially damaged, with the fuselage separated into two sections.
Investigation Findings
Investigations conducted after the accident revealed that the aircraft was operating satisfactorily prior to the event. No pre-existing mechanical issues were found. The probable cause was determined to be the application of considerable engine power when the aircraft was in an asymmetric landing configuration and at a speed probably below the single-engine minimum control speed (Vmc). Contributory factors included a lack of understanding between the two flight crew members regarding each other's actions immediately prior to the accident, the student/instructor relationship between the two crew members, and the prevailing dark night conditions.
Probable Cause
The official probable cause states: "The accident occurred most probably due to strong asymmetric thrust caused by increasing engine power on the operative engine when the aircraft was about to touch down with one engine feathered. Contributory factors were: - The lack of understanding between the two flight crew members of what each other was doing immediately prior to the accident, - The student/instructor relationship between the two and the prevailing dark night-time conditions."