What happened
On 12 July 2025, a KC-46A, tail number 18-6054, assigned to the 133rd Air Refueling Squadron, 157th Air Refueling Wing (New Hampshire Air National Guard), arrived at Fairbanks International Airport, Alaska, from Yokota Air Base, Japan. Upon landing, the aircraft exhibited abnormal vibration in both engines, necessitating maintenance.
A maintenance recovery team from McConnell Air Force Base arrived on 14 July to address the engine issues. On 16 July 2025, the team began a series of high-power engine-runs (HPER) intended to balance the engines and certify them for flight. After completing seven runs to stabilize the left engine, the team proceeded to work on the right engine. During the tenth HPER of the day, approximately at 1800 local time, the intense exhaust from the right engine caused two large sections of asphalt to lift from the ground. These blocks, measuring roughly 25 feet by 25 feet, became airborne and shattered into debris upon landing.
The investigation
The Accident Investigation Board examined the sequence of maintenance operations and the environmental conditions at the Heavy Cargo Ramp. The investigation focused on the impact of high-velocity exhaust and thermal energy on the airfield surface. Investigators reviewed the technical specifications of the engine runs and the physical state of the asphalt sealant at the time of the incident.
Findings
The board determined that the mishap was caused by persistent high temperatures combined with repeated high-speed exhaust from the right engine. This concentrated thermal and pneumatic force critically degraded the bituminous sealant holding the asphalt together, leading to the structural failure of the surface. A contributing factor was identified as the specific condition of the asphalt and sealant on the Heavy Cargo Ramp, which, while meeting standard inspection criteria, was unable to withstand the prolonged duration of high-temperature engine operations.