What happened
On March 26, 2005, a privately owned Dyn’Aéro MCR 4S was conducting a flight from Marmande to Nogaro with one pilot and one passenger on board. Upon arrival at Nogaro, the pilot performed a low pass of the airfield facilities before entering the landing circuit. The pilot opted to land on the paved runway 32 right, which was being used by gliders on the adjacent unpaved runway.
During the approach, the pilot configured the aircraft with landing flaps and maintained an approach speed of 130 km/h. The aircraft touched down between the end of the first third and the midpoint of the runway. As the pilot applied the brakes, the aircraft entered a shimmy oscillation. This instability persisted for several meters until the nose gear fork failed. The aircraft subsequently came to a stop after the propeller struck the ground, resting on two of its three blades. There were no fatalities or injuries reported, though the aircraft sustained damage to the nose gear and the propeller.
The investigation
The investigation focused on the mechanical failure of the nose gear assembly. It was determined that the composite material fork of the nose wheel failed at the point where it attaches to the gear leg. The investigation noted that the aircraft was not equipped with an anti-shimmy device. Due to the component being sent to the manufacturer for analysis following the accident, a detailed structural examination of the fork was not included in the final report.
Findings
- The pilot misjudged the remaining runway distance, likely due to the minimal tailwind component and the proximity to the end of the runway.
- This misjudgment led to the application of heavy braking.
- The heavy braking caused the shock absorber to compress beyond a specific threshold, triggering a shimmy oscillation.
- The structural failure of the nose gear fork occurred as a direct result of this unstable oscillation.