Had a BMW Mini come in with a crack noise when the steering was cycled from lock to lock on the floor, wouldn't do it when there was no load on the wheels(up on the ramp at work).
Answer. Traced it to 2 bolts missing that help secure the PAS pump to the subframe, tricky to see, they are top side of the subframe when viewing from the rear of the car when looking forward. Fitted 2 new bolts and the noise vanished.
Was a loud crack of a noise, sounded like something major was wrong!