Summary of the Accident
On 2 June 2016 at 13:00 local time, an F-16CJ (tail number 92-3890) assigned to the United States Air Force Air Demonstration Squadron (USAFADS), 57th Wing, Nellis AFB, Nevada, was destroyed by ground impact south of Peterson Air Force Base, Colorado. The mishap pilot ejected and sustained a minor injury; no other personnel were injured. The aircraft, valued at $29,466,037, was destroyed with no known damage to civilian property.
Sequence of Events
The F-16CJ was participating in a six-aircraft USAFADS flyby and airshow combination for a United States Air Force Academy graduation ceremony. The mission was uneventful until the aircraft entered the Peterson AFB traffic pattern in preparation for landing. While on downwind leg (parallel to and opposing the active landing runway), the highly experienced mishap pilot inadvertently placed the throttle to the cutoff position, resulting in engine shutdown. This action normally requires actuation of the throttle cutoff release trigger switch followed by full rotation of the throttle grip outboard, allowing the throttle to be retarded aft past the cutoff stop. Below the minimum altitude and airspeed required for either an engine restart or a flame-out landing, the pilot ejected over a grass field in El Paso County, Colorado.
Maintenance Issues
Examination of the throttle trigger by the Air Force Research Laboratory/Materials Integrity Branch identified intermittent sticking and binding of the throttle trigger, causing it to remain in a retracted/stuck position after actuation. The throttle trigger bushing was damaged and worn due to throttle trigger clevis pin misalignment, along with contamination from metallic-particle debris. Both conditions increased the likelihood of throttle trigger sticking and binding. Additionally, lubricant inconsistent with maintenance technical orders was found on the throttle trigger assembly, which exacerbated the debris contamination.
Findings
The Accident Investigation Board President determined, by a preponderance of the evidence, that the cause of the mishap was a throttle trigger actuation and subsequent malfunction (throttle trigger stuck in retracted position) followed by the pilot's inadvertent full rotation of the throttle grip while retarding the throttle aft to the cutoff position. Substantially contributing factors included maintenance technical orders that lacked sufficient detail to consistently identify either a throttle trigger clevis pin misalignment or a sticking/binding throttle trigger.