Main Shaft Play

The Nano CPS main shaft has a small black plastic collar below the swash plate, and the white main gear at the bottom of the shaft. Normally, the collar and main gear ride against the upper and lower shaft bearings respectively, which are mounted to the main frame. Between the two of them, there should not be any vertical play in the shaft.

Sometimes, a crash can slide the main gear down slightly on the shaft. If this happens, the shaft can slide up, which causes the pitch of the main blades to decrease. If your Nano can’t lift off the ground with full throttle, or gradually loses altitude during flight with full throttle, this is likely the cause. Simply press the main gear back on to the shaft until the vertical play is gone. Try to apply light, even pressure close to the gear hub when doing this, to avoid breaking the spokes that extend outward from the hub.

Less often, a crash can slide the collar along the main shaft, usually towards the swash plate, which will allow the main shaft to drop down, often to a point where the main gear no longer engages the motor pinion. If you can hear the motor turning at high RPMs but the main rotor isn't turning, this is the likely cause. You will have to remove the rotor assembly from the main shaft and reposition the collar so that it is exactly 18.83mm / 0.741” from the top of the main shaft. Once positioned correctly you will need to glue the collar to the shaft using a thin CA or other adhesive to prevent it from moving again, being careful not to accidentally glue any nearby moving parts.