What happened
On January 10, 2004, a Cessna 310-Q, registration EC-CNC, was conducting an instrument flight training mission departing from Cuatro Vientos Airport. The flight crew, consisting of an instructor and two students, had completed basic maneuvers and simulated VOR-DME approaches without incident.
During the final third of the downwind leg for runway 28, the crew attempted to extend the landing gear and discovered that the nose gear failed to deploy. After notifying the tower, the crew abandoned the circuit and attempted both standard and emergency gear extension procedures, but the nose gear remained retracted. Due to the approaching sunset, the pilot declared an emergency but elected to wait for other traffic to clear before landing.
To avoid the poor surface conditions of the unpaved runway, the pilot opted to land on the asphalt runway. Approximately 40 meters before touchdown, the pilot cut the mixture, closed the fuel valve, and disconnected the electrical system and magnetos. The aircraft landed with full flaps, utilizing the main gear while maintaining a high nose attitude to decelerate as much as possible before touchdown. The three occupants (one instructor and two students) were uninjured and evacuated the aircraft on their own.
The aircraft sustained significant damage, including deformation and breakage of the nose gear doors, a bent nose gear torque tube, broken spars and ribs in the nose gear housing, deformed propeller blades, and damage to the nose cone, antenna, and pitot tube.
The investigation
Following the accident, the aircraft was inspected in a hangar. While no visible damage was found inside the gear bay, the connection bar between the initial gear and the retraction mechanism was found to be bent.
Upon correcting the deformation to perform functional tests, investigators observed that one of the two bearings in the nose gear extension/retraction hinge would bind at certain points. After disassembly, the bearing was found to be poorly lubricated. Once the part was properly greased and reinstalled, the gear functioned correctly both electrically and manually.
Findings
- The nose gear failed to extend due to inadequate lubrication of one of the hinge bearings.
- At the time of the accident, the Cessna 310-Q service manual did not include specific inspection or lubrication requirements for these particular bearings.
- The lack of a maintenance requirement made it impossible to identify the deteriorating lubrication state through routine inspections.