What happened
On July 22, 197 and, a private VFR flight departed from the Biel-Kappelen airfield on runway 22. The aircraft, a Cessna 210 registered as D-ELVY, was carrying a pilot and one passenger toward Basel. During the takeoff roll, the pilot attempted to relieve pressure on the nose gear by applying back pressure on the elevator. This action caused the aircraft nose to dip, prompting the pilot to increase the elevator input. As the aircraft crossed a taxiway mid-runway, a sudden impact occurred. The pilot responded by pulling the elevator fully back and reducing power. The aircraft pitched forward, striking the ground with the engine cowling. The aircraft slid on its nose for approximately 440 meters before coming to a halt at the left edge of the runway. The nose gear assembly separated from the aircraft, coming to rest about 60 meters behind the main wreckage.
The investigation
The investigation focused on the structural failure of the nose gear assembly. Examination of the nose gear revealed that the AN-5 attachment bolt, responsible for securing the upper part of the shock strut within the fork, had suffered a clean shear failure. Testing confirmed the bolt material hardness was within the required specifications. However, the investigation established that the attachment lugs connecting the fork to the firewall, the nose wheel steering linkage, and the piston rod of the shock strut had all fractured, causing the entire unit to detach. While the damage prevented a determination of the exact oil level in the shock strut at the time of the accident, the physical evidence pointed to a mechanical overload.
Findings
- The primary cause of the accident was the failure of the nose gear attachment components.
- The investigation concluded that the shock strut likely contained insufficient oil, causing the strut to bottom out completely during the takeoff roll.
- This bottoming out generated extreme impact forces that sheared the attachment bolt and caused the subsequent structural failure of the steering linkage and mounting lugs.
- The aircraft weight and center of gravity were within permissible limits, and the pilot was found to be in good health with sufficient flight experience.