What happened
On 27 April 2025, a Siai Marchetti S.205 22/R, registration G-VELA, was conducting a private cross-country flight from Knettishall Airfield to Turweston Aerodrome. Following a brief stop for refueling at Turweston, the pilot commenced the return leg to Knettishall. Shortly after takeoff, the crew detected a brief smell of electrical burning in the cockpit, which subsided quickly.
As the aircraft approached Knettishall, the pilot attempted to extend the landing gear, but the system failed to respond, and the gear down indicators remained unlit. After two unsuccessful attempts to cycle the gear, the pilot tried to use the manual emergency extension system. However, the manual crank handle jammed after only approximately 11 of the required 2/29 rotations.
Seeking a safer environment for landing, the pilot declared a PAN and diverted to Norwich Airport, which offered superior emergency services. During a low pass at Norwich, air traffic controllers observed that the landing gear was only partially extended. The pilot subsequently performed a landing in this configuration, resulting in no injuries to the two occupants, but causing damage to the aircraft's propeller, landing gear, and fuselage underside.
The investigation
Following the incident, the AAIB examined the recovered aircraft and its landing gear assembly. Investigators found that the nose landing gear was jammed and protruding partially from its bay. The investigation established that the nosewheel was off-centre due to a failure in the steering mechanism.
Technical analysis revealed that a steering centring pin within the control quadrant had become misaligned and disengaged from its guide bars. This prevented the nosewheel from returning to a centred position. It is believed that when the gear was retracted after the departure from Turweston, this off-centre position caused the nose gear to jam within the bay. This mechanical obstruction placed an overload on the electrical actuation motor, which likely caused the initial smell of burning.
Findings
- The primary cause of the landing gear failure was a worn and misaligned steering centring pin that had disengaged from its guide bars.
- This misalignment prevented the nosewheel from centring, causing the nose gear to jam during the retraction phase of the flight.
- The resulting mechanical resistance caused an overload of the normal extension/retraction motor and led to the seizure of the emergency extension system.
- The pilot's decision to divert to an airfield with better facilities and the use of air traffic controllers to consult an experienced instructor contributed to the safe outcome.