What happened
On 20 December 2016, a Reims Cessna F1t2N Skyhawk, registration G-DUVL, was performing a private flight at White Waltham Airfield in Berkshire. The pilot reported a smooth touchdown on the grass runway with minimal impact. However, as the aircraft decelerated to approximately 35 kt, a loud bang was heard and the right side of the aircraft dropped. The aircraft subsequently veered to the right by about 120 degrees before coming to a stop. Upon inspection, the pilot discovered that the right main wheel assembly had detached from the landing gear leg, resulting in minor damage to the tailplane and elevator. There were no injuries to the pilot or the three passengers on board.
The investigation
Investigators examined the failed right main landing gear leg and found that the failure occurred near the top fastener of the aerodynamic fairing. The examination of the four screws securing this fairing revealed inconsistencies; two screws were magnetic and heavily corroded, while the other two were non-magnetic and bright. These screws varied in length by as much as 11 mm. The top fastener, which was of the correct length and material, had made contact with the leg, creating a dent 6.8 mm in diameter and 1.6 mm deep.
Microscopic analysis of the fracture surface revealed multiple cracks originating from this dent. The presence of beachmarks and corrosion indicated that a fatigue crack had developed and grown over time due to cyclic loading during landing and taxiing, eventually leading to an overload failure. While the specific screw involved was the correct length, the investigation noted that screws on the opposite side also showed witness marks of contact with the gear leg, suggesting insufficient clearance between the fairing and the leg.