An Air Force MQ-9 Reaper drone, valued at approximately $13 million, crashed into the Mediterranean Sea on December 16, 2022. An accident investigation attributed the crash to a failure of a critical ring that secured the propeller, leading to its disconnection mid-flight.
The MQ-9 belonged to the 432nd Wing at Creech Air Force Base in Nevada and was operated remotely by a pilot and sensor operator from the 20th Attack Squadron at Whiteman Air Force Base in Missouri. It took off from an undisclosed location within the U.S. European Command area. An accident investigation report released on July 30, 2023, detailed the events surrounding the crash.
On the day of the incident, around 5 p.m. Greenwich Mean Time, the Reaper was flying at cruising speed and altitude when its engine torque mysteriously dropped to zero within seconds, while the engine speed surged beyond its normal range. Despite increasing the throttle to full power, the pilot could not regain engine torque. The drone maintained altitude briefly but began losing airspeed and altitude thereafter.
The crew declared an emergency and attempted to regain control, planning a forced landing in a remote, uninhabited area. After about 15 minutes, they observed metal debris in the engine oil and decided against restarting the engine. As the situation deteriorated, they were instructed to crash the Reaper into the water. The final descent occurred at 5:23 p.m.
The Reaper was lost in the Mediterranean, preventing a thorough hardware analysis. General Atomics, the drone manufacturer, examined flight data logs, concluding that the loss of engine torque coincided with the propeller’s disconnection. The incident was attributed likely to the failure of a spiral lock ring inside the gearbox, which is known to suffer from wear and tear. Honeywell, the maker of the MQ-9’s engine, had implemented a policy to replace these rings every 3,000 flight hours to mitigate failures, but the crashed Reaper had only reached about half of that threshold.
While investigators proposed several theories for the premature wear of the ring, the unrecoverable drone limited the ability to confirm these theories. The investigation found no evidence of deficiencies in mission planning or preflight procedures related to the mishap.
