What happened
During a scheduled test flight following its manufacture in Seville, an Airbus aircraft was conducting maneuvers as part of a pre-delivery program for the Turkish Air Force. After departing from Runway 09 at Seville-San Pablo Airport, the crew executed a left turn toward the north. During this phase of flight, three of the four engines became stuck at high power settings.
Despite efforts by the crew to adjust the thrust levers back to a normal mode, the first, second, and third engines failed to respond to commands. The crew attempted to mitigate the situation by selecting idle, but the engine power remained fixed. Due to this loss of control over engine thrust, the decision was made to perform an emergency return to the airport.
While on approach, the aircraft struck power lines, resulting in a stall and subsequent impact in an open field approximately 1.6 km north of the airfield. The collision was followed by a post-crash fire that resulted in the total destruction of the airframe. The accident resulted in four fatalities and two survivors.
Findings
Investigations into the malfunction revealed that the engine control software had been incorrectly installed during the final assembly process of the aircraft.