‘Misaligned’ fan blades, loss of thrust caused Thunderbird F-16 crash

The crash of an F-16 late last year in California during a routine training flight that prompted the pilot to eject was caused by “misaligned” fan blades, which prompted engine failure.

On Dec. 3, 2025, a F-16CM Fighting Falcon, assigned to the Air Demonstration Squadron “Thunderbirds” at Nellis Air Force Base, Nevada, crashed near Trona, California. The aircraft, which was destroyed upon impact, resulted in the complete loss of the $33.4 million aircraft.

The pilot was able to safely eject and only suffered minor injuries. There were no fatalities or reported damage to civilian property.

During the training flight, the pilot experienced a loss of thrust at low altitude and initiated corrective action procedures but was unable to regain sufficient thrust, according to the recently released Air Combat Command report.

The planned mission was to perform a vertical loop followed by a barrel roll, with the pilot separating from the formation during the loops to rejoin during the rolls due to neck stiffness.

As the pilot was rejoining the formation, the engine experienced a stall and “the jet just … stopped midair,” the pilot describes in the report. The pilot placed the engine control switch to its secondary control, causing the engine to “flameout” and later reported that “it sounded like things were grinding” in the engine.

Around four minutes after the loss of thrust, the pilot ejected from the aircraft, which tumbled down at a rate of approximately 1,200 feet per minute, according to the report.

The investigation found that the cause of the mishap was three turned variable vanes, or blades, in the 4th and 5th stages of the Pratt & Whitney F100-PW-229 engine, which caused irregular airflow and increased “vibratory stresses” on the 5th and 6th stage compressor blades.

Then, one blade each in the 5th and 6th stages failed due to fatigue and fractured and separated during flight, causing “catastrophic” engine damage at low altitude with no ability to sustain operations or recover, per the report.

The investigators could not determine what caused the turned vanes due to a lack of sufficient evidence, but a subsequent inspection of the engine revealed missing blades from the 5th and 6th stages.

The aircraft in question had also been flown the day prior to the accident and had no discrepancies or maintenance write-ups, but the report detailed that maintenance personnel cannot easily inspect the 4th and 5th stage variable vanes or the 5th and 6th stage of the engine core without removing the engine from the aircraft and opening the rear compressor case.

The report highlighted that a documented foreign object damage event occurred in October 2021 when the engine was previously installed in a separate aircraft. It resulted in damage to the 3rd stage of the Inlet Fan Module and to the turbine exhaust cone assembly, but maintenance technicians did not note any damage to the 4th, 7th or 8th stages.

This resulted in no further inspections of the core, but since that event, damage was detected on three separate occasions in the 1st stage and a “foreign material” was recovered from the 4th stage.

The report notes that the foreign object damage “substantially contributed” to the mishap since the 5th and 6th stages of the engine were not inspected afterward, as damage was not seen in the engine’s preceding section.

“Additionally,” the investigator writes, “the core of the engine is only inspected during scheduled maintenance when a core component reaches its overhaul threshold, leaving time for potential damage to progress undetected.”