On 28 August 1962, while on an intermediate stop during a ferry flight to Moscow for acceptance testing, Ka-22 01-01 rolled to the left and crashed inverted, killing the entire crew. The cause was found to be the starboard rotor collective pitch control linkage, and further inspection found that two of the other three Ka-22s suffered from similar problems. Subsequently, in order to improve stability and control, a complex differential autopilot was installed. This sensed attitude and angular accelerations, and fed into the control system.