USAF F-35A crashed in Alaska after hydraulic fluid froze in landing gear

A United States Air Force (USAF) F-35A Lightning II that crashed during an emergency approach to Eielson Air Force Base (EIL), Alaska, on January 28, 2025, was brought down by frozen hydraulic fluid contaminated with water, according to the official accident investigation report. 

The aircraft, tail number 19-5535, was operated by the 355th Fighter Squadron of the 354th Fighter Wing. The pilot ejected safely and sustained only minor injuries. The $196.5 million jet was destroyed within the base perimeter, and no ground injuries were reported. 

A cascading failure in extreme cold 

The investigation revealed that water had contaminated the hydraulic fluid in the aircraft’s landing gear system. When exposed to Eielson’s sub-zero temperatures, the water froze, preventing the nose and main landing gear struts from fully extending or retracting. 

This malfunction caused the jet’s “weight on wheels” sensors to incorrectly register that the aircraft was on the ground. As a result, the aircraft’s flight control system switched to “ground mode,” severely degrading its flying qualities and making it uncontrollable. 

Nearly an hour of troubleshooting before the crash 

After detecting that the nose landing gear was canted to the left, the pilot and ground controllers initiated a “conference hotel,” an emergency consultation with Lockheed Martin engineers. For nearly 50 minutes, they worked through possible solutions, leading to two touch-and-go attempts aimed at resetting the system. 

However, the investigation found the call fell short in key areas. Engineers never requested environmental data that might have revealed the freezing issue and largely overlooked fault codes from the main landing gear. Their recommendations failed to resolve the malfunction, and after experiencing uncontrollable oscillations, the pilot ejected safely just moments before impact. 

The Air Force has published details on the F-35 crash in Alaska earlier this year. Water in hydraulic fluid froze resulting in landing gear issues, and further the gear strut did not fully extend leading to the weight on wheels sensors telling the fly by wire system the plane was… pic.twitter.com/ynPYNnGRwo— Scott Manley (@DJSnM) August 26, 2025

Maintenance and oversight failures 

Testing showed that up to one-third of the hydraulic fluid in the struts was water. The contamination likely resulted from poor storage practices and inadequate oversight of the squadron’s hazardous materials program. The investigation found that barrels of hydraulic fluid were left unsecured and exposed to humid conditions and inclement weather during deployments, including one at Kadena Air Base, Japan. Furthermore, these barrels were not properly tracked. 

Investigators also cited maintenance procedural lapses, including improper hydraulic servicing and failures to detect water contamination before the flight, as contributing factors. 

Similar issues flagged after the crash 

Just days after the mishap, a second Eielson F-35 experienced a landing gear malfunction during takeoff under similar conditions. That aircraft landed safely, but tests confirmed water in the landing gear struts and replicated the freezing issue, highlighting the systemic nature of the problem. 

Eielson AFB is a critical hub for North American air defense, located within the Alaskan Air Defense Identification Zone (ADIZ), where Russian aircraft frequently operate. It also hosts the large-scale Red Flag-Alaska training exercises and supports both US and allied operations across the Pacific. The post USAF F-35A crashed in Alaska after hydraulic fluid froze in landing gear appeared first on AeroTime.

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