Cessna T210M N6850B accident near Pueblo, Colorado

Probable cause

Failure of the landing gear to fully extend due to a failed o-ring in the nose gear actuator piston and a broken seal in the emergency landing gear extension system.

NTSB analysis

The pilot heard an unusual sound as he retracted the landing gear after takeoff and the amber gear warning light was illuminated. The pilot referenced the emergency procedures and made two unsuccessful attempts to manually extend the gear. After engaging the autopilot, the pilot then checked the hydraulic reservoir in the cockpit and it was empty. At the advice of an air traffic controller, the pilot added a quart of engine oil in the hydraulic reservoir and attempted another manual gear extension. The pilot was still unable to extend the gear. The pilot made a low pass by the control tower and a controller informed him that no landing gear were visible. The pilot then made a gear-up landing as directed by the Pilot Operating Handbook; however, according to airport personnel, the pilot landed with the nose gear down and the main landing gear retracted. The airplane skidded on its belly and the left horizontal stabilizer was damaged. According to a representative of the repair facility that fixed the airplane, an o-ring in the nose gear actuator piston had failed. In addition, a seal in the emergency extension system had also failed. Once the failed o-ring and seal were replaced, the landing gear functioned normally.

Text from the NTSB. Open the NTSB docket for CEN11LA357 for the full record.