What happened
On August 25, 2009, a PIPER PA 46-500TP (registration N31145) was performing a private flight from Ibiza Airport, Balearic Islands, following an earlier leg from Switzerland. After departing from runway 24, the pilot requested a climb to 3,000 feet, at which point a red "GEAR" warning light illuminated in the cockpit, indicating the landing gear was not fully retracted.
In an attempt to troubleshoot, the pilot cycled the landing gear three times, adjusting speed according to the flight manual. While the gear appeared to lock down during the descent, the warning light reappeared whenever the pilot attempted to retract the gear. The pilot also requested the passenger to visually inspect the main gear legs from the rear seat, but the issue persisted. Consequently, the pilot decided to return to Ibiza.
During the final approach, the gear lights indicated the gear was down and locked. The pilot executed a long flare and landed the aircraft gently. However, as the pilot attempted to exit the runway by applying a slight right rudder, the aircraft came to an abrupt and unexpected halt. Both the pilot and the passenger were able to exit the aircraft uninjured.
The investigation
Investigators examined the aircraft's nose gear and found that the nose gear wheel had rotated 90 degrees relative to the aircraft's longitudinal axis. The tire casing was destroyed, and the wheel showed significant wear from sliding on the pavement.
Upon inspection of the nose gear mechanism, investigators found that the scissor linkages—the components responsible for transmitting torque and limiting strut travel—had become loose. Specifically, the screw intended to join the scissor linkages through their lugs was found attached to the lower linkage, but the essential crown nut and split pin were missing. The screw itself showed no signs of deformation, excessive stress, or thread damage, suggesting the failure was not caused by an impact or overloading.
Findings
- The primary cause of the incident was the separation of the nose gear scissor linkages.
- This separation allowed the nose wheel assembly to rotate perpendicular to the direction of motion when the pilot applied rudder to exit the runway.
- The failure was caused by the loss of the crown nut and split pin from the screw holding the linkages together.
- It is believed the nut loosened progressively due to a faulty or missing split pin, likely caused by improper installation, the use of incorrect materials, or the pin's absence.
- The loss of the nut likely occurred during the initial takeoff run, which also triggered the cockpit gear warning light during the subsequent climb.