History of the Flight
The pilot of Piper PA-34-200 Seneca, registration G-EMER, conducted a thorough pre-flight check including a visual inspection of the nose landing gear bay. Normal nose wheel steering was confirmed during taxiing. The takeoff proceeded normally until the landing gear was selected up after takeoff. The red 'gear unsafe' light remained illuminated, indicating that the landing gear was in transition. The pilot selected the gear down, achieving two green lights for the main landing gear but no light for the nose landing gear. The red light remained illuminated, confirming the issue was with the nose gear.
The pilot reported the situation to Old Sarum Radio and performed the manual extension procedure, including activating the emergency gear extension system, which releases hydraulic pressure to allow the gear to free-fall. Cockpit indications remained unchanged. Additional actions such as changing indicator light bulbs, applying positive 'g', and side-slipping did not improve the situation.
Witnesses observed that the nose leg was only partially extended, approximately 15 to 20 degrees short of the fully extended position, and the nose wheel was angled relative to the aircraft centreline. The pilot could see the gear using a convex mirror mounted on the left engine nacelle but could not determine exact extension or wheel centering.
After discussing options via radio, the pilot decided to attempt a touch-and-go landing on the main gear only to jolt the nose gear into the locked position. The approach was made to Runway 24 at Old Sarum, a grass runway 2,558 feet long. Weather was fine with a surface wind from 240°(M) at 10 kt. The intended firm landing was gentle. As the pilot applied power, the aircraft pitched nose down despite full aft yoke, causing the unlocked nose gear to contact the surface. The nose leg retracted further, and the aircraft nose and both propellers struck the grass runway. The aircraft decelerated smoothly and came to rest centrally on the runway approximately 1,000 feet from touchdown. No fire occurred, and the uninjured pilot vacated the aircraft without assistance. Damage included the nose cone, nose landing gear assembly, and both propellers.
Aircraft Examination
Inspection of the nose landing gear assembly revealed that the lower arm of a U-bracket had fractured, allowing the quadrant casting and the upper section of the track to pivot upwards. This placed bending loads on the upper arm of the U-bracket, which showed initial signs of failure. The fracture faces were significantly abraded, preventing determination of the failure cause. The roller assembly, normally captive within the track, was found outside the track against the outer side of the track mounting.
Analysis
With the quadrant and hinged track section able to pivot upward, a larger gap formed in the curved track channel. When the nose gear was down and locked, the roller assembly remained captive within the upper track section, allowing normal steering. However, as the nose leg retracted, the roller moved along the track until it encountered the gap, leaving the channel and moving aft and down in contact with the outside of the track mounting. The leg continued retracting but ultimately could not reach the fully up position because the hydraulic actuator could not overcome the abnormal loads.
When gear was selected down, the actuator rotated the leg toward the down position, but the roller remained outside the track. Again, the actuator could not overcome resistance, leaving the leg 15 to 20 degrees from the down and locked position. The roller's displacement from the aircraft centreline caused the observed nose wheel deflection. The failed U-bracket was located such that it could not be detected during pre-flight inspection, and once the roller left the track, no pilot action could lock the nose gear down.
Conclusion
The accident was caused by the failure of the U-bracket which allowed the nose landing gear roller assembly to leave the guide track, making it impossible to lock the nose landing gear down.