What happened
On June 13, 1964, a Swissair Convair CV-990A Coronado, registration HB-ICE, was performing a series of equipment check flights at Zurich-Kloten Airport. The flight program involved multiple takeoffs and landings in quick succession to demonstrate pilot proficiency and aircraft systems.
Following an initial landing without braking, the aircraft performed several subsequent maneuvers. During the taxiing period after the third landing, air traffic control reported smoke emanating from the left landing gear assembly. The crew, noting that the smoke had ceased, proceeded with the scheduled program. However, during the fourth takeoff, the aircraft began losing components from the left landing gear group. Shortly after liftoff, the crew observed what appeared to be a fire in the left gear assembly. The incident caused a total failure of both hydraulic systems, significantly impairing the aircraft's controllability. Despite these severe complications, the crew managed to return to the airfield and landed at 15:27, narrowly avoiding the runway edge.
The investigation
Investigators examined the mechanical state of the landing gear, including the wheels, tires, and braking systems. The investigation involved energy calculations to determine if the temperatures reached the threshold for the fusible plugs to activate. Experts from the Swiss Federal Institute of Materials Testing were consulted to analyze the tire components. The inquiry also reviewed the flight logs and the specific sequence of the flight program to assess the thermal load placed on the braking and tire assemblies.