Nose Wheel Steering
With a 20 ft diameter tail rotor and a large pitch range, pilot has precise and powerful control over taxi heading.
By a coincidence, I think I picked up the first CH-47A delivered to the Army with the left rear wheel power steering. ( tail no 13106, and it had the water landing kit as well-1964 ). Early Chinook drivers will recall the ease with which slightly ham-footed pilots could put in too much pedal for a taxi turn, and deposit droop stops onto the tarmac. The next step involved getting long 4 X 6 lumber and placing it against the fuselage, so that when the blades slowed down during shutdown, they would hit the lumber, rather than taking divots out of the fuselage. ( Major Allen Murphy, are you out there somewhere? ). My recollection is that the flight manual had a ground taxi limit of 3/4 inch of pedal input to prevent this from happening. But what pilots really did was to taxi with the swivel locks in the two aft wheels, and the forward wheels off the ground. Much easier to do, and with some collective applied to get the front wheels airborne, droop stop contact really could not occur.
One can see why the steerable rear wheel appeared on the CH-47.
Over the years, there has been a lot of beer consumed arguing the merits of the 53 vs the 47, but ground handling never comes up!