What happened
On November 5, 1965, a Cessna 210 D, registration OE-DEG, was conducting instrument flight procedures training at Zurich-Kloten Airport. The flight, operated by a flight school, included a flight instructor, a student pilot, and a passenger. Following an initial approach and a missed approach on runway 16, the crew attempted to retract the landing gear once a climb rate of 500 feet per minute was established.
However, the landing gear lever failed to return to its neutral position, and the green indication light did not illuminate. Despite multiple attempts by the instructor to cycle the gear and the use of the emergency hand pump, the mechanism remained stuck. During low-level inspections of the airfield, it was observed that the left main gear was only partially extended. As the crew prepared to land on runway 02, the instrument panel began to overheat due to hydraulic system issues. Upon landing, the aircraft could only maintain a straight path for approximately 200 meters before tilting heavily to the left. The aircraft eventually veered 90 degrees and came to a stop 340 meters past the runway threshold.
The investigation
Investigators examined the hydraulic system and the landing gear actuation mechanism. The investigation confirmed that the hydraulic fluid levels were sufficient and the relief valves were functioning within prescribed pressure limits. A critical finding was a torsional fracture in the drive shaft of the left main landing gear. Material analysis ruled out fatigue or manufacturing defects, pointing instead to a single instance of extreme overload. \n## Findings
- The primary cause of the accident was a mechanical failure of the landing gear mechanism.
- The drive shaft of the left gear suffered a torsion break caused by excessive stress.
- The investigation considered that a previous hydraulic issue on October 31, 1965, involving low fluid levels and overheating, might have left the left gear strut improperly seated or not fully locked in its end position.
- It was determined that if the strut was not fully locked, the sudden application of ground loads during the landing sequence could have applied enough vertical pressure to trigger the shaft fracture.
- No injuries were reported among the three occupants, though the aircraft sustained heavy damage to the left wing, horizontal stabilizer, and gear doors.