What happened
On 3 February 2001, a Piper PA-3/4-200T, registration G-BMUT, was undergoing a flight test at Newcastle Airport. The flight was intended to evaluate the aircraft's performance and instruments following recent maintenance, which included the replacement of the nose-wheel centering spring assembly.
During the takeoff roll on Runway 25, the pilot noted that the Air Speed Indicator (ASI) failed to accelerate beyond approximately 60 knots. Despite this, the commander continued the takeoff, lifting off at an estimated speed of 85-90 knots. Upon reaching 200 feet, the pilot selected the landing gear in the up position. At this moment, the ASI dropped to 40 knots, and the crew discovered the second ASI had reached its low-speed stop.
While performing a low-level circuit, the crew observed that while the main landing gear lights were green, the nose landing gear (NLG) green light remained unlit, and the red gear-in-transit light stayed illuminated. The crew attempted to extend the nose gear by recycling the selector, using the emergency extension device, and performing various maneuvers, but the gear failed to deploy. After flying at FL60 to monitor the situation, the crew decided to return to Newcastle to land on the main wheels only. The aircraft touched down on its main gear, causing the nose to sink and strike the runway. Both crew members escaped the no injuries incident, though the aircraft sustained damage to the nose gear doors, forward fuselage, and propeller blade tips.
The investigation
The AAIB investigation focused on why the nose landing gear failed to extend. Examination of the assembly revealed that the tail of the bolt used to attach the forward end of the centering spring assembly to the nose leg had become latched over the door actuation aft tube assembly.
Investigators found that an incorrect hexagonal bolt had been used during recent maintenance. This bolt had been installed in the wrong orientation—with the head facing upward—contrary to both the aircraft's service manual and manufacturer service bulletins. This improper installation caused the bolt tail to foul and deflect the aft tube assembly forward during gear retraction, preventing the gear from subsequently extending.