4468, It would appear we are having a Apples and Orange's discussion when we each talk about our recollection of the Chinook.
I qualified my experience ending with the C Model having flown a lot of A models, some B models, and C-, full C models in the standard US Army Configurations.
Chinook 240 kindly provided a copy of the CH-47 Familiarization Manual that addresses the LCT system which I knew as the Speed Trim System.
DASH was not installed on any of the Models I flew.
That was part of the upgrade to the D Model.
The D Model Operators Manual I linked has a description of the AFCS Components in Section 2-5-7 (d) and (f) where the Differential Air Speed System (DASH) is discussed and mentions that it incorporates airspeed hold above 40kts and also provides positive stick gradient through the autopilot.
So....does this clarify things a bit for you.
You are talking D Model or later when you talk DASH and PSG services it provides.
That does not apply to earlier models of the US Standard Configuration A-C Models.
Here is the Army Operators Manual for the D Model.....perhaps not the latest edition but good enough for our purposes.
http://www.chinook-helicopter.com/Pu...520-240-10.pdf
If you move to page 51 of the Fam Manual provided by 240.....you can see a discussion and diagram of the LCT or Speed Trim System as I have described it in an earlier Post.
You can see the DCP Link in the diagram.
That is controlled by the Trim Wheel in the Cockpit which moves the cyclic fore and aft and its position is indicated by a display. marked in "Inches of Displacement".
The use of that Trim Wheel is for comfort purposes primarily and has limitations for on-ground use.....in the A-C Models it was a Two inch Aft of center Cyclic movement with the DCP adjusted to Zero.
The other half of the DCP actuator acts to facilitate a Positive Stick Gradient.
In my Operational Unit anytime that Actuator (either half of it) went U/S it was noted in the Maintenance Record of the Aircraft and labeled "In-Operative"....with no limitations on Flight applying.
In the D Model Operators Manual we see an Altitude Hold Capability which was not present on the A-C models.