S-64 Rear Seat
Maxtorq,
CH-54A/S-64E had a modified S-61 type AFCS, Rear seat accomplished yaw control thru the twisting of the cyclic, but required manual beeping to extend the pitch/roll axis authority range. CH-54B/S-64F had the RH-53D type AFCS. Yaw control was still done thru twisting the cyclic, but the pitch/roll authority range extension was different. My memory is hazy on this part, but I think the range was extended thru a trim reshift if you either got to some threshold of the existing authority or touched the electronic cyclic stops. Think it was the former. Maybe some old Crane pilot can help here. In any case, yaw was available on both, and thru twisting the cyclic. People will notice that on the newer SA fly-by-wire controls now in flight test, the yaw controls utilize electric pedals, making pure single axis yaw inputs a lot easier.
Thanks,
John Dixson