Ice formation from contaminated hydraulic fluid led to F-35A flight control failure in Alaska
Posted on August 27, 2025 by alert5
Water contamination in hydraulic fluid caused ice formation that led to the Jan. 28 crash of an F-35A Lightning II at Eielson Air Force Base, Alaska, resulting in a $196.5 million total loss, according to an Air Force accident investigation board report released this week.
The mishap pilot from the 355th Fighter Squadron ejected safely with minor injuries after the aircraft became uncontrollable following a second touch-and-go landing attempt. The investigation determined that approximately one-third of the hydraulic fluid in the aircraft’s landing gear struts was water, which froze during extended ground operations in sub-zero temperatures and prevented critical flight control systems from functioning properly.
Colonel Michael B. Lewis, the investigation board president, found by preponderance of evidence that the contaminated hydraulic fluid combined with extreme cold temperatures caused ice to form inside the landing gear struts. When the struts could not fully extend due to ice blockage, Weight-on-Wheels sensors incorrectly indicated the aircraft was on the ground while it was actually airborne, causing the flight control system to switch to “on-ground” mode and rendering the aircraft uncontrollable.
Technical Failure Cascade
https://alert5.com/2025/08/27/ice-formation-from-contaminated-hydraulic-fluid-led-to-f-35a-flight-control-failure-in-alaska/
