Investigation finds $13 million US military Reaper drone crashed into the sea after an unexplained failure saw its propeller fall off

The US military lost one of its Reaper drones after a part failed, causing the propeller to fall off on a mission last year and forcing the $13 million combat aircraft to make a crash landing in the Mediterranean Sea, a recently released investigation revealed.

A US Air Force investigation report released last month determined that the costly mishap, which occurred in December 2024, was caused by a failure in a mechanical part connecting the MQ-9A Reaper drone’s engine with its propeller. The specific reason for that failure, however, was unclear as the drone wasn’t retrieved.

The Reaper drone, a combat and reconnaissance platform, belonged to the 432nd Wing of Nevada’s Creech Air Force Base and was scheduled to carry out an operational mission on December 16 over or around the Mediterranean Sea. The remotely piloted aircraft took off at 1 pm Zulu time from an undisclosed location within the European Command area of responsibility.

About four hours later, while the drone was flying at cruising air speed and altitude, its engine torque display dropped from normal levels to a complete loss of torque within a second.

The MQ-9 “experienced a loss of air speed and began an uncommanded descent,” the report said.

As the drone descended, operators — members of the 20th Attack Squadron from Missouri’s Whiteman Air Force Base — spent 16 minutes trying to maintain control and restore thrust to the MQ-9 falling out of the sky.

The recently released Air Force investigation, first reported by Air & Space Forces Magazine, said that the operator eventually realized that the drone’s engine had internal damage, and they shut it down. The crew then decided to make a forced landing in the Mediterranean — the last data received suggested came in just as the MQ-9 was about to impact the water.

There were no injuries or damage to civilian property, the report said, sharing that the drone — valued at exactly $13,154,585 — was not recovered.

Air Force investigators said that “the cause of the mishap was a failure within the Splined Coupling Assembly.” This “led to a sudden and permanent mechanical decoupling of the propeller from the engine resulting in an unrecoverable loss of thrust.”

General Atomics, the US defense company that makes the MQ-9 Reaper, said that the Spiral Retaining Ring was the most likely cause of the failure, although it was impossible to determine with certainty because the wreckage — and, with it, evidence — could not be collected.

The Reaper, the US military’s drone of choice for combat and reconnaissance missions, has suffered a string of mishaps in recent years, including several “Class A” incidents, meaning that the incident resulted in damage greater than or equal to $2.5 million or a destroyed aircraft. Air Force safety data shows 5 in 2021 and just as many the year prior. More recent safety data wasn’t immediately available.

American Reaper drones have also been targeted by US foes. In 2023, for instance, a Russian Su-27 fighter jet clipped the propeller of an MQ-9 operating above the Black Sea, forcing the uncrewed aircraft to crash land in the water.

That year, Russian aircraft also repeatedly harassed US Reaper drones operating over Syria, engaging in behaviors like flying in close proximity to the MQ-9s. In one incident, a Su-35 fighter jet released flares on a drone and damaged its propeller.

The Iran-backed Houthis have also shot down several Reaper drones that the US had been using to support its military operations against the Yemeni rebels.

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