Linkage
From RC Helicopter Wiki
Linkages are the series of pushrods, bellcranks, mixer arms (such as the washout, Bell-Hiller mixer or swashplate) that transfer servo movements to the aircraft's control surfaces; namely, the main rotor and tail rotor.
Ensuring that the linkages are set up correctly, with good linkage geometry and little slop helps ensure that the aircraft will fly well.
