Accident Summary
On 28 October 2020 at 1944 Zulu time, an unmanned MQ-9A aircraft, tail number 12-4179, crashed into a mountainous region at an undisclosed location in Afghanistan. The mishap aircraft (MA) was operated remotely by a Mission Control Element (MCE) consisting of a mishap pilot and a mishap sensor operator, assigned to the 482d Attack Squadron. The aircraft sustained heavy damage upon impact and was subsequently rendered unsalvageable by kinetic means. No damage to civilian property, injuries, or fatalities occurred. The loss of government property was valued at $14,128,206.
Sequence of Events
Approximately 40 minutes before the crash, the mishap sensor operator observed a drop in oil level and alerted the mishap pilot. The MA lost 100 percent of its oil between 1903z and 1908z. The MCE declared an emergency, performed required checklists, and notified the recovery location of their intent to return. Shortly after rerouting, the Combined Air Operations Center (CAOC) directed the MCE to attempt to salvage the MA in the event of an emergency landing. At 1924z, the engine failed. The MCE identified an ad hoc landing site but, while attempting to avoid a possible structure, crashed into a ridge at 1944z.
Maintenance Findings
During the MA's previous sortie two days earlier, a gradual drop in oil level was noticed, prompting an early return. The Mishap Ground Crew (MGC) diagnosed the source as two broken clamps and a small hole in the oil line. The primary maintenance technician assigned to repair the oil line (MGC 1) did not remove associated components beforehand as required by the relevant technical order (TO), causing difficulty installing the replacement line.
Investigation Findings
The Abbreviated Accident Investigation Board (AAIB) President determined, by a preponderance of the evidence, that the oil leak reduced the oil level to 0 percent, causing the engine to fail and preventing the MA from returning safely to the recovery location. Additionally, two factors were found to have substantially contributed to the mishap: (1) MGC 1 failed to follow relevant TOs while replacing the oil line and clamps; and (2) the Mishap Flight Chief (MFC) directed MGC 1 to disregard TOs in an effort to expedite the repair.
Regulatory Context
Under 10 U.S.C. § 2254(d), the opinion of the accident investigator as to the cause or contributing factors set forth in the accident investigation report may not be considered as evidence in any civil or criminal proceeding arising from the accident, nor may such information be considered an admission of liability by the United States or any person referred to in those conclusions or statements.