Accident Overview
On 24 June 2020, at 0933 Zulu time, an MQ-9A unmanned aircraft, tail number 08-4051, crashed in an undisclosed location within the United States Africa Command (US AFRICOM) Area of Responsibility. The aircraft was assigned to the 162d Wing, Arizona Air National Guard, and operated by the 214th Attack Squadron Mission Control Element at Davis-Monthan Air Force Base, Arizona. The loss of government property was valued at $11,290,000. There was no reported damage to civilian property, injuries, or fatalities.
Sequence of Events
At approximately 0640Z, the ground control station displayed warnings of low fuel level in the header tank. The mishap pilot and sensor operator began procedures to clear the fault. The pilot noted through fuel calculations that the measured fuel was well short of expected levels. With assistance from the mission crew commander, the crew diagnosed the problem. The sensor operator used the primary camera to visually inspect the aircraft and discovered a severe fuel leak from the fuselage.
At 0723Z, the crew initiated a return to base at maximum airspeed. After further analysis, they determined the fuel leak was catastrophic. Coordinating with the Combined Air Operations Center Remotely Piloted Aircraft Liaison Officer, the crew planned to crash the aircraft. The CAOC directed the crash in a manner that would minimize chances of a successful recovery effort.
Fuel exhaustion occurred at 0914Z. The mishap pilot then controlled the aircraft's glide to optimize the impact point. As the aircraft lost altitude, the pilot increased airspeed through the crash, which occurred at 0933Z. The wreckage was not recovered.
Cause and Contributing Factors
The Abbreviated Accident Investigation Board president found, by a preponderance of the evidence, that the cause of the mishap was a fuel leak from the Forward Electric Fuel Heater, which caused fuel exhaustion before the aircraft could be safely returned to the launch and recovery element.
The board also found that each of the following factors substantially contributed to the mishap: (1) A delinquent Time Compliance Technical Order to correct a known MQ-9 deficiency, (2) The design of the fuel leak detection system, and (3) Lack of guidance and tolerances for the MQ-9 fuel system.
Aircraft and Crew Information
The MQ-9A (tail number 08-4051) was assigned to the 162d Wing, Arizona Air National Guard, and operated from Davis-Monthan AFB. The mishap was investigated by an abbreviated accident investigation board as per United States Air Force regulations.