What happened
On 4 May 2023, approximately 9.5 hours into its mission, an unmanned MQ-9A with tail number 18-4369 experienced a significant propulsion system anomaly while operating within the United States Africa Command (AFRICOM) Area of Responsibility. The aircraft was being operated remotely by a Mission Control Element assigned to the 184th Attack Squadron.
During the flight, the engine's internal components experienced abnormal contact between rotating and static parts. This mechanical issue triggered the Digital Electronic Engine Controller (DEEC) to adjust torque and fuel flow in an attempt to stabilize engine speed. These adjustments led to a loss of thrust and indications of an engine fire. In response to the fire risk and loss of power, the crew performed an intentional engine shutdown and feathered the propeller.
Because no suitable recovery airfield or Launch and Recovery Element was within the aircraft's glide range, the crew coordinated with the Air Operations Center to steer the aircraft over water toward potential recovery assets. The aircraft continued its descent until it impacted the water at an undisclosed location. The impact resulted in the complete loss of the aircraft, valued at $21,794,224. There were no injuries or fatalities reported.
The investigation
The investigation conducted by the Abbreviated Accident Investigation Board examined the mechanical sequence leading to the engine's failure and the subsequent flight path of the aircraft. Investigators reviewed the actions taken by the pilot and sensor operator, as well as the coordination with various operations centers during the descent. Because the aircraft was not recovered from the water, a physical post-mishap inspection of the engine core could not be performed to identify the specific source of the internal contact between components.