What happened
On September 8, 2021, at 16:30 local time, a PIPER PA-34-200, registration EC-IHS, was conducting a dual flight instruction mission at the Requena aerodrome in Valencia, Spain. The flight, involving an instructor and a student, was performing maneuvers to prepare for a multi-engine rating exam, including turns, slow flight, and stalls.
Following a series of maneuvers and a simulated engine failure, the crew performed a touch-and-go maneuver. After landing and configuring the aircraft for takeoff by retracting the flaps and applying power, the nose gear collapsed approximately two seconds into the takeoff roll. The aircraft's nose dropped, causing the plane to slide along the runway on its fuselage. The instructor took control and applied the brakes to bring the aircraft to a halt. Both occupants, the instructor and the student, were uninjured and evacuated the aircraft safely after the fuel and electrical systems were shut down.
The investigation
The investigation focused on the mechanical failure of the nose gear assembly. Physical examination of the aircraft revealed that the propeller blades had deformed due to impact with the pavement, and the lower fuselage sustained damage from the sliding motion.
Investigators inspected the nose gear assembly and found that while the emergency extension system functioned correctly, the mechanical locking mechanism had failed. Upon disassembly of the nose gear downlock tensioner, investigators discovered that the upper attachment pin was bent. Furthermore, during the subsequent repair process, it was noted that the nose wheel axle had also become bent.
Findings
- The primary cause of the incident was the uncommanded retraction of the nose gear, triggered by the failure of the tensioner bolt that holds the articulated strut in the extended position.
- The failure of this locking bolt prevented the strut from remaining properly locked, allowing the gear to fold into the compartment under the loads experienced during the takeoff roll.
- It is possible that cumulative stresses from repeated landings during flight instruction may have progressively damaged the tensioner bolt.
- The nose wheel axle was also found to be bent as a result of the impact.