What happened
On 22 July 2018, a Cessna 750 Citation X+, registration N752TX, was preparing for a flight from Cork Airport to Gander, Newfoundland. The aircraft, carrying two crew members and six passengers, taxied from Stand 16 toward Runway 16. During the taxi phase, the pilot noticed some difficulty with the nose wheel steering, though the crew believed the pre-flight inspections had been completed successfully.
As the aircraft began its take-off roll, the pilot encountered a heavy vibration originating from the nose wheel. At a groundspeed of 67 knots, the pilot decided to abort the take-off. The aircraft reached a maximum groundspeed of 74 knots before decelerating and coming to a stop on the runway. While there were no injuries to the passengers or crew, the aircraft sustained substantial damage to its nose gear and forward structure.
The investigation
The AAIU investigation focused on the mechanical state of the nose gear assembly and the sequence of events leading to the vibration. Investigators examined the nose gear leg, which had suffered significant structural damage, including a 90-degree rotation of the lower leg and the disintegration of both tires. The investigation also recovered a torque link release pin and an internal retention pin from the runway.
Technical inspections of the nose gear leg, performed by the manufacturer, revealed that several components had failed. These included snapped lugs on the power steering unit, a broken mounting for a cable pulley, and damage to the actuator rod end lug. Furthermore, investigators identified a discrepancy in the Aircraft Maintenance Manual (AMM) regarding the behavior of the torque links, noting that the manual's description of the links being spring-loaded was inaccurate.
Findings
- The primary cause of the vibration and subsequent damage was the failure of the nose gear assembly components during the take-off roll.
- The nose gear leg and nose structure sustained significant damage, including a tear in the aircraft's nose structure and bending of the nose gear bay doors.
- The investigation found that the lower torque link had not been spring-loaded as suggested by the AMM, but had instead fallen under gravity.
- A search of the NASA ASRS database revealed a pattern of similar occurrences in related Cessna Citation models, often involving incorrectly installed or undetected torque link pins.