ED Decision 2003/16/RM
The rotorcraft must have satisfactory ground and water handling characteristics, including freedom from uncontrollable tendencies in any condition expected in operation.
ED Decision 2003/16/RM
The rotorcraft must be designed to withstand the loads that would occur when the rotorcraft is taxied over the roughest ground that may reasonably be expected in normal operation.
CS 29.239 Spray characteristics
ED Decision 2003/16/RM
If certification for water operation is requested, no spray characteristics during taxying, take-off, or landing may obscure the vision of the pilot or damage the rotors, propellers, or other parts of the rotorcraft.
ED Decision 2003/16/RM
The rotorcraft may have no dangerous tendency to oscillate on the ground with the rotor turning.