Training: Loose Squat Switches Contribute to Runway Overrun

 - June 3, 2013, 12:33 PM

A Bombardier Learjet 35A, unable to stop during its landing roll on 5,420-foot Runway 4/22 at Oregon’s McMinnville Municipal Airport (MMV), ran off the end of the pavement May 13, substantially damaging its wings and fuselage. The Part 91-operated aircraft was on a post-maintenance positioning flight with a three-member Evergreen International Aviation crew aboard. No one was injured in the accident.

The pilot reported that as the airplane touched down he deployed the spoilers, and then pulled the power levers to the thrust-reverser detent position. The deployment indicators did not illuminate. He recycled the thrust levers, but again the reversers did not deploy. Both the pilot and copilot attempted to troubleshoot as the airplane continued along the runway. The pilot then applied pressure to the brakes, but did not feel a response; the copilot also attempted, but reported that the pedals felt loose and the airplane did not slow down.

As the airplane approached the threshold, the pilot engaged the steering lock switch and attempted to steer the nosewheel, but the airplane did not respond. Just before reaching the runway end, he activated the emergency braking lever; however, the airplane rolled off the runway end, through a set of instrument landing system antennas, and down an embankment.

Subsequent examination revealed that the mounting screws for both the left and right main landing gear squat switches were loose and that the switches had backed away from their mounting pads.