HILL AIR FORCE BASE -- A new Air Force investigation has found that the engine failure that caused a Hill Air Force Base F-16 to crash last spring likely could not have been detected by maintenance workers -- a finding that is contrary to the initial crash report.
On May 4, 2012, a F-16C Falcon crashed in the northern part of the Utah Test and Training Range about 70 miles west of Ogden, about an hour after takeoff when it lost engine thrust.
The pilot, who was participating in a routine readiness-training session, safely ejected after steering the plane away from nearby mountains and the Great Salt Lake. The jet was destroyed and the Air Force valued the loss at nearly $24 million.
The pilot and the jet were assigned to the 421st Fighter Squadron at Hill. Nobody was injured in the accident and no other damage was reported.
The initial accident investigation report was completed in early September by the Air Combat Command at Joint Base Langley-Eustis in Virginia.
That investigation said failure of the number 17 blade in the first stage fan of the engine caused the mishap. Cracking along the surface and eight years of operating fatigue contributed to the structural failure. As a result, the blade broke free from its supporting structure and caused catastrophic damage to the engine fan, compressor and turbines.
The initial report also said that the blade's surface inconsistency should have been detected during the inspection when it was installed in April 2004.
But the investigation was recently reopened after ACC Vice Commander Lt. Gen. William J. Rew requested it, questioning the report's findings that the problem should have been discovered during routine maintenance.
In an addendum to the initial report, released by the ACC, the Air Force states that "The ability to detect (the blade's surface inconsistency) was limited due to lubricants applied during transfer and machining. Additionally, procedures did not require an inspection, and feature-by-feature inspections were not typically completed for new blades arriving from the manufacturer."
An overall inspection occurred at Tinker Air Force Base in Oklahoma during fan assembly buildup. The report says that after the initial blade installation there was no scheduled inspection or maintenance that could have resulted in the anomaly being discovered. The blade was never removed after 2004.