What happened
On February 11, 2011, a NetJets Transportes Aéreos Hawker 800XP, registration CS-DRK, was conducting a position flight from Warsaw to Moscow Vnukovo Airport. During the approach to runway 24, the crew selected the landing gear down; however, while the main landing gear locked into position, the nose gear indicated a red light and the extension pin remained in the up position.
The crew initiated a go-around and entered a holding pattern to perform emergency checklists. They attempted to recycle the gear using the normal hydraulic system and executed high-load maneuvers to encourage extension, but the nose gear remained retracted. When the crew transitioned to the auxiliary hydraulic system, they noted a "clunk" and increased wind noise from the nose gear area, followed by a sudden increase in hydraulic pressure that prevented further pumping.
Having exhausted all available procedures, the crew elected to perform a controlled gear-up landing. To minimize potential damage, the crew burned off as much fuel as possible to reduce the aircraft's weight and approach speed. The aircraft touched down 820 meters from the runway threshold and slid approximately 480 meters along the centerline. The crew evacuated via the over-wing emergency window; no injuries were reported, and the aircraft sustained only minor damage to the fuselage belly.
The investigation
The GPIAAF investigation involved an initial on-site examination in Moscow and a subsequent detailed inspection in Chester, UK, after the aircraft was repaired for a ferry flight. Investigators examined the nose landing gear (NLG) assembly, the drag stay, and the door mechanism.
Technical inspections in the UK revealed that certain dimensions of the nose gear door mechanism were out of tolerance. Specifically, Dimension Y was found to be significantly outside the permitted range. Furthermore, investigators identified scratch marks on the drag stay cam, likely caused by improper tooling during maintenance.
Subsequent fleet inspections by the operator revealed a pattern of similar incidents involving the same aircraft type during winter operations in cold climates. These inspections discovered that bushings on the door hinge assembly were migrating from their castings, causing significant stiffness or even seizure of the nose gear door struts.