A Gulfstream G450 was damaged last April after its nose gear retracted on a taxiway following an attempt by the crew to remove the landing gear safety pins, according to a preliminary report from Austria’s accident investigation branch. The crew failed to remove landing gear safety pins before takeoff and then decided to remove them on a taxiway after returning to the departure airport.
Several seconds after taking off from Salzburg, Austria, bound for Bangor, Maine, the copilot moved the landing gear lever to the UP position, but the gear remained down and locked. The crew suspected that the landing gear safety pins were still installed and decided to return to Salzburg Airport.
After the G450 landed and cleared the runway, controllers cleared the twinjet to taxi to the parking ramp. But when the crew noticed an increased rolling resistance, they stopped the aircraft on the taxiway and the copilot exited to check the tires and see if the safety pins were installed.
At the same time the copilot left the aircraft, the pilot left the cockpit with the engines still running to inform the two passengers in the cabin of the situation. According to the preliminary report, the crew did not inform the control tower they were stopping and the tower tried without success to make contact with the crew.
Seeing that safety pins were in fact installed, the copilot tried to remove them, but failed because of the hydraulic pressure on the gear. He then operated the gear door control valves of the nose and main landing gear several times and installed the gear door control valve pins.
This closed the gear doors, the hydraulics depressurized, and the copilot was able to remove the pins. However, a moment later, the gear doors opened, "the nose gear folded and the aircraft’s nose lowered and hit the taxiway." The pilot then switched off the engines.
Although the preliminary report does not include an official cause, it did note, “No indication could be found that both the ‘Landing Gear Failure to Retract’ and the ‘Attempted Landing Gear Retraction with Safety Pins Installed’ checklists were executed from the time the installed safety pins were detected until the time of the accident.”