December 15, 2016 (by Lieven Dewitte) - The crash of an Air Force Thunderbird F-16CM in Colorado Springs last June was caused by a throttle trigger malfunction and inadvertent throttle rotation, according to an accident investigation report released yesterday.
Picture of the downed Thunderbird near Powers and Fontaine who crashed on June 2nd, 2016. The pilot ejected safely. [Photo by Brennan Linsley, The Associated Press]
The 41-page report was released more than six months of probing the crash
and the actions of the pilot.
The pilot, Maj. Alex "Tuna" Turner, was able to steer the jet towards a grass field and safely eject. The F-16CM, valued at approximately $29 million, was wrecked.
The Thunderbird flying team had just finished its annual flyover above Falcon Stadium for Air Force Academy graduation and were on final approach to the airport when Turner reported a problem.
He told air traffic control the engine was suddenly cycling off and on in the descent.
The accident review board found that when Turner was pulling the throttle back to reduce engine power for his descent, the pilot actually wound up pulling the throttle so far back that it killed the turbine. This way the pilot accidentally shut his own engine off three times, the report said.
According to the report, the pilot inadvertently rotated the throttle during landing, placing it into an engine cut-off position. Normally, this full rotation cannot occur unless a throttle trigger is affirmatively actuated or pressed. However, the throttle trigger was "stuck" in the 'pressed' position.
The investigation found debris in the throttle trigger, along with wear on the trigger assembly. Analysis by the Air Force Research Laboratory/Materials Integrity Branch found the trigger remained “stuck” after being pressed.
The throttle assembly on the plane was tested repeatedly by investigators who were able to recreate the sticky trigger. The trigger's parts were pulled apart and examined under a microscope, which identified wear issues.
Investigators said the jet had nearly half a ton of kerosene aboard when it crashed, this dismissing the conspiracy theories that claimed the plane ran out of fuel.
The jet lost thrust, and although Turner attempted to restart the engine, it was impossible due to the aircraft’s low altitude.
The board praised Turner for staying with the plane to low altitude in order to steer it away from homes. The board found that Turner ejected at a lower-than-recommended altitude because he wanted the jet to crash in an open field.
The accident board also cleared the pilot of any wrong-doing, allowing him to return to the sky with a clean record. At the time of the accident, Turner had logged 1,200 flight hours as an Air Force pilot and more than 270 combat hours over Libya and Iraq
. In fact, he is the pilot who flew what is believed to be the two longest Viper combat missions in history back in 2011.
He resumed demonstrations with the team.
The board found that the Air Force had no set method for adjusting the throttle trigger, with different manuals on the plane containing contradictory information for the ground crewman.