Primary finding
Probable cause
The malfunction of the throttle servo which resulted in the complete loss of engine power.
Investigator assessment
Analysis narrative
The operator of the unmanned aircraft system (UAS) reported that during a test flight, the throttle servo malfunction resulting in complete loss of engine power. The pilot was able to maneuver the UAS to a safe location where it impacted terrain, resulting in substantial damage to the fuselage and flight control surfaces.