PACAF’s investigation discovered water-contaminated hydraulic fluid froze and triggered a touchdown gear malfunction, resulting in the lack of an F-35A at Eielson AFB.
An Accident Investigation Board (AIB) report launched on Aug. 26, 2025, by the U.S. Pacific Air Forces (PACAF) has make clear the circumstances that led to the lack of a U.S. Air Drive F-35A Lightning II throughout a coaching mission at Eielson Air Drive Base, Alaska, on Jan. 28, 2025. As we reported again then, the jet crashed inside the fence line of the bottom, with a video exhibiting the F-35 spinning in direction of the bottom with its touchdown gear prolonged.
The plane, assigned to the 355th Fighter Squadron of the 354th Fighter Wing, was destroyed after a failed restoration try, although the pilot safely ejected with solely minor accidents. Based on the press launch concerning the investigation, the whole loss was estimated at $196.5 million.
Based on the official AIB report, the mishap was triggered by hydraulic fluid contaminated with water, which froze within the frigid Alaskan temperatures and prevented the right extension of the touchdown gear. This malfunction set off a sequence of occasions that finally rendered the plane uncontrollable, resulting in the crash.
Takeoff and Preliminary Malfunction
The accident occurred shortly earlier than 1 p.m. native time, throughout a routine coaching sortie. After takeoff, the pilot tried to retract the touchdown gear, however the nostril touchdown gear (NLG) didn’t align and remained canted between 17 and 25 levels to the left. This irregularity was shortly identified as a malfunction, and the pilot entered a holding sample whereas troubleshooting the issue with the help of the Supervisor of Flying (SOF) and Lockheed Martin engineers which have been contacted by cellphone.
On the time, temperatures at Eielson have been effectively beneath freezing- with the noticed temperature being −17 °C (1.4 °F) – and the plane had already spent appreciable time uncovered to the chilly throughout pre-flight checks. These circumstances performed a central function within the failure, because the AIB later decided.
Makes an attempt to Recenter the Touchdown Gear
To right the problem, the pilot was suggested to carry out touch-and-go maneuvers, in an effort to assist realign touchdown gear. On the primary try, the nostril gear didn’t recenter. A second try, flown at greater velocity, partially improved the scenario, lowering the cant angle to round 6 levels.
Nevertheless, ice buildup inside the principle touchdown gear struts prevented them from totally extending. Consequently, the plane’s Weight-on-Wheels (WoW) sensors falsely registered that the jet was on the bottom, although it was airborne. This sensor error triggered the flight management system to change to the “on floor” flight management regulation, severely disrupting the jet’s dealing with.
The pilot out of the blue skilled uncommanded yaw and pitch oscillations. With the plane quickly changing into uncontrollable, assuming an perspective with 30-40 levels pitch up and a 38 levels left roll at simply 372 ft above floor stage and a velocity of 222 knots, the pilot initiated the ejection. The escape system labored as designed, and the pilot landed safely close by.
Plane Loss and Speedy Response
Moments after ejection, the F-35A stalled at an altitude of two,665 ft AGL, spiraled uncontrolled and impacted the bottom with a 116-degree proper financial institution inside the perimeter of Eielson Air Drive Base, thus being destroyed by the crash and subsequent fireplace. Emergency responders have been on scene inside one minute, stories the AIB.
No accidents to base personnel or civilians have been reported, though the mishap represented a serious materials loss. The destroyed plane, serial quantity 19-5535, was valued at $196.5 million, says the service.
Root Trigger Evaluation
The AIB decided that the basis reason for the crash was hydraulic fluid contaminated with water, which froze within the excessive chilly and prevented the touchdown gear from totally extending. As a result of the touchdown gear couldn’t correctly seat into place, the system transmitted false indicators to the plane’s Weight on Wheel sensors, resulting in the faulty floor mode activation.
The investigation traced the contamination again to upkeep and unsafe supplies (HAZMAT) administration shortcomings, particularly inadequate manning and frequent supervision adjustments. Based on the report, hydraulic servicing at Eielson was carried out with improper procedures.
Upkeep personnel used much less fluid than required attributable to tools limitations, as a hand cart was employed as an alternative of a nitrogen servicing cart, and the strains weren’t adequately flushed. This left water contamination contained in the system, because the AIB decided water was already within the struts previous to the servicing performed three days earlier than the mishap.
Moreover, barrels of hydraulic fluid weren’t correctly saved or tracked, and inadequate staffing and supervision contributed to the issue. The AIB highlighted that these failures created an surroundings the place water infiltration into hydraulic techniques might go undetected.
Determination-Making and Human Components
Whereas the technical malfunction was the direct reason for the mishap, the AIB additionally famous contributing human elements. Particularly, the choice to proceed airborne troubleshooting with successive touch-and-go maneuvers was known as into query, though the AIB extremely praised the efforts by all events concerned.
Nevertheless, the board discovered that the persistence in making an attempt to mechanically recenter the touchdown gear, somewhat than getting ready for an emergency touchdown with the gear misaligned, elevated the probability of catastrophic failure. In actual fact, the report mentions {that a} Lockheed Martin upkeep round from April 2024, stating that WoW sensor points might result in plane controllability points, might have been probably referenced, and the pilot might have been suggested to conduct a deliberate full cease touchdown or a managed ejection as an alternative of a second touch-and-go.
That stated, the report emphasised that the pilot was a completely certified and extremely skilled F-35A evaluator pilot, with a complete of over 2,700 flight hours, together with 555 hours within the F-35A. The pilot additionally acquired a “Commendable” ranking within the space of Flight Management and Teacher Efficiency for demonstrating distinctive ability and information.
A Comparable Incident
The Jan. 28 crash was not an remoted case. Simply 9 days later, on Feb. 6, one other F-35A skilled a comparable nostril gear malfunction, mentions the report. In that occasion, the pilot acquired a nostril wheel gear unsafe indication after takeoff, flying for roughly 40 minutes with the touchdown gear lowered earlier than touchdown uneventfully.
The report indicated the unsafe nostril gear indication was as a result of uplock lacking the curler and rotating the nostril wheel 10 levels to the left in an identical method to the crashed plane. Moreover, whereas touchdown the nostril wheel went from 10 levels to the left to five levels at landing.
Floor testing then confirmed that frozen hydraulic fluid contamination was once more accountable. The report concluded that it was seemingly water was already current throughout earlier flights, however no malfunctions occurred as temperatures have been greater and water didn’t have time to freeze earlier than takeoff.
