Incident
On a local test flight after the replacement of engine number four, an aircraft departed N'Gaoundéré Airport at 1250 local time. The captain used the flight to train the copilot, who was being considered for promotion to captain. While cruising in good weather, the aircraft banked left, entered a dive, and crashed approximately 37 kilometers southwest of N'Gaoundéré.
When the airplane failed to return to its base, search and rescue operations were initiated. The wreckage was located in an isolated area the following day. All eight occupants were killed.
Investigation
Investigators determined that the accident involved a collision with trees while the aircraft was banking substantially to the left. However, the exact cause of the bank and subsequent collision could not be specified due to the destruction of the wreckage, which limited available evidence.
Several aspects of the flight remained unexplained: the flight duration was longer than expected, radio contact was not maintained, engine number four stopped operating, and the propeller pitch on engine number three was not in a normal setting. Additionally, a farmer reported seeing the aircraft flying at low altitude minutes before the crash. The reason for this low-altitude flight could not be determined.
Probable Cause
The official probable cause states that the accident was caused by a collision with trees while the airplane was banking substantially to the left. The underlying reason for the bank could not be identified due to insufficient evidence.