What happened
On 12 August 2021, a Supermarine Aircraft Spitfire Mk 26, registration G-CIEN, was performing a private flight at Newtownards Airport, County Down. The pilot, who had recently acquired the aircraft, was conducting a revalidation check flight following various modifications.
Upon landing on Runway 21, the aircraft was decelerating along the centreline when it suddenly veered toward the right. Despite the pilot applying full left braking and left rudder, the aircraft could not be corrected. The excursion resulted in the left wingtip, propeller, and engine cowling scraping the runway surface. The aircraft eventually came to a stop off the runway, sustaining damage to the landing gear, engine cowlings, and wingtip. There were no injuries to the pilot.
The investigation
The AAIB investigation focused on the structural integrity of the left main landing gear. To examine the internal components, the gear leg was removed and the upper tube was physically cut open. This revealed that a fillet weld connecting a splined shaft to a thick washer had failed. This failure allowed the lower part of the gear leg to rotate, which altered the wheel alignment and caused the sudden veer.
Investigators also reviewed the aircraft's maintenance history, noting that the aircraft had undergone a heavy landing in July 2017. While the landing gear had been removed for inspection following that event, the specific failed weld was impossible to inspect due to the design of the leg, which prevents access to the internal splined shaft without cutting the tube.
Findings
- The primary cause of the excursion was the failure of a weld between the splined shaft and a washer within the left main landing gear leg.
- This failure allowed the lower leg and wheel assembly to rotate, leading to the loss of directional control.
- The investigation found that the weld exhibited minimal penetration, suggesting that manufacturing variability may have weakened the joint.
- It is possible that the 2017 heavy landing had already compromised the weld, but the design of the landing gear prevented this damage from being detected during subsequent inspections.
Safety action
- The Light Aircraft Association (LAA) has issued a warning to all UK owners of Spitfire Mk 26 aircraft regarding the risk of hidden weld damage following heavy landings.
- The LAA is currently reviewing the design of the Mk 26 undercarriage, specifically addressing the lack of access for inspecting critical welded components.