What happened
On 28 October 2020, an unmanned MQ-9A, tail number 12-4179, crashed into a mountainous region in Afghanistan. The aircraft was being operated remotely by a Mission Control Element assigned to the 482d Attack Squadron.
The incident began approximately 40 minutes before impact when the sensor operator noticed a rapid decline in oil levels. Within five minutes, the oil level had dropped from 100 percent to zero. Following the loss of oil, the engine failed, leaving the aircraft unable to reach its intended recovery location. While attempting to find an emergency landing site and avoid a man-made structure, the pilot was forced into a trajectory that resulted in a collision with a ridge. The aircraft sustained heavy damage upon impact and was subsequently destroyed via kinetic means. The loss of the government property was valued at over $14 million, though there were no fatalities or injuries.
The investigation
The investigation examined the maintenance history of the aircraft following a previous sortie two days earlier. During that prior flight, the pilot had also noted a drop in oil levels, which led to a safe return to base. Upon inspection, ground crews identified broken clamps and a hole in the oil line.
Investigators looked into the repair process for this oil line. The technical order (TO) required specific components—including the propeller and engine plenum assembly—to be removed to provide sufficient workspace for a proper repair. The investigation established that these steps were bypassed during the recent maintenance session.