What happened
On 2 December 2019, at approximately 1537 hours local time, an F-1 6CM Block 40, tail number 90-0714, was returning to Kunsan Air Base, South Korea, following a local training sortie. The aircraft, assigned to the 80th Fighter Squadron, 8th Fighter Wing, was part of a four-ship formation when it made initial contact with Runway 36.
Upon touchdown, the aircraft's right main landing gear collapsed, causing the jet to yaw sharply to the right and depart the prepared runway surface. The pilot attempted to maintain control and regain flight, but was unsuccessful. The aircraft slid across the infield, intermittently becoming airborne before coming to a halt approximately 2,200 feet from the initial touchdown point, rotated 150 degrees from the original heading. The pilot successfully ejected with minor injuries, but the aircraft was completely destroyed.
The investigation
The Accident Investigation Board examined the mechanical failure of the landing gear system and the historical context of similar incidents within the F-16C fleet. Investigators analyzed flight data, witness testimony, and engineering reports to determine why the right main landing gear failed during the landing phase. The board also reviewed existing technical orders and the timeline for mandatory hardware upgrades intended to prevent such occurrences.
Findings
- The primary cause of the mishap was a failure of the right main landing gear downlock actuator, which led to the collapse of the gear and subsequent loss of aircraft control.
- The investigation identified that the mechanical tension during landing was sufficient to overcome the force of the downlock actuator, a phenomenon related to the "spin-up/spring-back" condition where landing gear components vibrate and potentially unlock during wheel rotation.
- A significant contributing factor was the timeframe allowed for the implementation of Time Compliance Technical Order 1F-16-2855, which mandates the replacement of heavy-weight downlock actuators and brackets. At the time of the accident, the window for compliance had not yet expired.