What happened
On July 5, 1962, at 07:51 CET, a Caravelle SE-210/III, registration LN-KLR, operated by Scandinavian Airlines System (SAS), was performing a scheduled flight from Zurich to Düsseldorf. During the takeoff roll on runway 34 at Zurich-Kloten, the crew experienced intense vibrations originating from the nose landing gear at approximately 100 knots.
Recognizing the instability, the crew immediately aborted the takeoff. To prevent further damage to the compromised gear, the crew utilized the aircraft's braking parachute rather than the wheel brakes. The aircraft came to a halt 2,390 meters from the start of the runway. While there were no fatalities or injuries among the 46 passengers and 6 crew members, the nose gear assembly sustained heavy damage, with the axle housing being ground down significantly. The aircraft was able to return to service following repairs.
The investigation
Investigators examined the components of the nose gear assembly and the maintenance history of the aircraft. The investigation focused on the recent replacement of the nose wheels, which had occurred on June 29, 1962, in Stockholm.
Physical evidence showed that the left wheel nut, along with its cone and securing screw, was found 650 meters from the start point. The right wheel and its assembly were located 1,059 meters from the start, while the left wheel was found much further away at 1,560 meters. Analysis of the wheel axle revealed that the axle and a bearing part had been installed in a reversed orientation. Furthermore, the investigation found that the securing screw for the left wheel nut had become loose.
Findings
- The primary cause of the incident was the loosening of the left wheel nut, which allowed the nose wheels to detach from the aircraft.
- This loosening was made possible because the securing screw, which lacks its own independent locking mechanism, was not properly tightened.
- The investigation identified a secondary contributing factor: the nose wheel axle had been installed in a reversed direction, which could have accelerated the loosening process once the securing screw failed.
- While the reversed installation was a critical error, it was noted that the maintenance checks (K-Check and V-Check) did not explicitly require a torque verification of the securing screws, making the defect difficult to detect through standard visual inspections.