History of Flight
The flight was a dual check ride with an examining instructor from the local flying club at Elstree. After completing upper air exercises, a normal touch-and-go was performed on Runway 26. The next approach was planned as a flapless landing with a touch-and-go. During downwind, the landing gear was verified as down and locked via three green lights. On final approach, the speed was adjusted to 90 knots. The aircraft touched down approximately 80 metres short of the runway threshold on a paved but untended area. This area consisted of rough concrete marked with a white cross, adjacent to the runway tarmac, with an upslope leading to the threshold.
Upon landing, the right main landing gear (MLG) fork assembly fractured at the axle, releasing the wheel, which struck the right flap. The nose landing gear then collapsed, causing both propellers to contact the runway. The instructor took control, but the left MLG subsequently collapsed, and the aircraft slewed to the right, departing the runway. During the slide, fuel drain valves protruding below the wing were damaged, leading to fuel leakage. There was no fire. The pilots, wearing lap and diagonal harnesses, shut down the aircraft and exited without injury. The airfield rescue vehicle arrived within two minutes.
Witnesses confirmed the landing gear was down and the landing was short of the threshold. One witness, an airfield worker, observed the approach and assessed the aircraft as low and fast, prompting preparation of the rescue vehicle.
Runway Examination
AAIB examination of ground marks showed the first evidence of aircraft contact was 80 metres short of the runway threshold. Near this point, a missing section of tarmac (23 cm wide, 14 cm long, 3–4 cm deep) was noted. The first mark was a straight line consistent with ground contact of the right MLG fork after wheel loss, with another mark indicating the right MLG door being torn off. About 6 metres further, the right propeller blades struck the ground, and after another 8 metres, similar strikes from the left propeller indicated nose landing gear collapse. Marks continued for approximately 20 metres, followed by a scar from right wing tip contact. The aircraft continued along the runway supported by two right propeller blades and the left main gear. Some 94 metres from the threshold, the aircraft veered right, with the left tyre leaving a skid mark before the left MLG collapsed, and then the aircraft left the runway to the right and stopped.
Aircraft Examination
All landing gear damage was consistent with overloads during the accident sequence. The right MLG fork assembly was fractured at the axle attachment. The right flap, retracted, was damaged aft of the right MLG leg, consistent with wheel strike. The right MLG lock link assembly was over centre and locked, and the actuator was at maximum stroke (gear down). The left MLG was intact but not locked down; its lock link mechanism was extensively damaged, and the actuator eye-end bearing had fractured from overload in bending. The nose landing gear was retracted in its bay, with one door torn off and the other damaged; the actuator rod was bent 90° but at maximum stroke.
Metallurgical examination of the right MLG wheel and fork assembly determined the fork failed in overload due to bending. No pre-existing defects, fatigue cracks, corrosion, or material defects were identified that could have influenced the failure. Material tests confirmed the fork conformed to specifications for 2014-T6 aluminium alloy.
The aircraft had been involved in a previous landing accident in May 1999 where the nose landing gear collapsed. However, no pre-existing defects were found with the right MLG, and the previous event was not considered a factor.