No damage, light friction, spins freely

Propeller must be clean of all mud and dirt and free of damage, otherwise propeller imbalance will cause vibration and image distortion on the camera.

Light friction

The screws are tight enough to allow the propellers to fold out without falling down, but loose enough that they can fold in when the aircraft touches down on the ground.

Spins freely

Rubbing wires or friction in the motor could cause the motor to fail in flight and the aircraft to land unexpectedly in the field.