Accident Overview
On 2 March 2022, at 11:24:56 local time, a United States Air Force F-16CG Fighting Falcon, tail number 89-2035, call sign VIPER 21, assigned to the 555th Fighter Squadron, 31st Fighter Wing at Aviano Air Base, Italy, experienced separation of the left main landing gear wheel during takeoff from runway 05. The mishap pilot (MP) was leading a two-ship formation on an air tasking order mission.
During the takeoff roll, the anti-skid caution light illuminated, prompting the MP to abort the planned departure. The mishap wingman conducted an aerial inspection and, along with air traffic control, initially reported a blown tire. Security forces later found the separated wheel on the airfield, confirming the loss of the entire left main landing gear wheel.
Gear-Up Landing
After consultation with supervisory personnel and a flight safety engineer, the MP decided to land with the landing gear retracted. At 13:40:59 local time, the aircraft touched down on runway 05 and skidded to a stop at 13:41:26. The pilot was uninjured and egressed safely as emergency vehicles responded. The aircraft sustained significant damage to its ventral fins and electronic countermeasures pod due to sliding on the runway. Repair costs were estimated at $6.1 million.
Cause Determination
The Abbreviated Accident Investigation Board found, by a preponderance of the evidence, that the mishap was caused by failure of the left outboard main landing gear wheel bearing. Excessive heat and friction from the failed bearing caused softening and deformation of the bearing cone. Rotational forces led to undesired rotation of the cone around the axle, friction-welding it to the stationary spacer. Shear forces then fractured the spacer's anti-rotational tab, allowing the spacer to rotate counter-clockwise. Friction between the rotating spacer and wheel nut sheared the locking tab, loosening the nut during takeoff. Once the wheel separated, the only safe recovery option was a gear-up landing.