Originally Posted by
vilas
The second question why disconnect ATHR? Because there's ATHR protection for underspeed and overspeed. It will not allow it to go below VLS for the present flap configuration and that's more than VFE Next.
Vilas, I know I probably have the wrong end of the stick, but the QRH says
- If VLS is greater than VFE NEXT (overweight landing case), the FLAPS lever can be set in the required next position, while the speed is reduced to follow VLS reduction as surfaces extend. The VFE warning threshold should not be triggered.
In this case, disconnect the A/THR. A/THR can be re-engaged when the landing configuration is established.
which the way I read it is to select flaps when at VLS, even above VFE next and track the VLS down as the surfaces extend.
So I’ve never understood why the A/THR has to be disconnected. Eg if Vls was above VFE next, and you select say, vfe next -5, the A/THR will keep the speed at VLS above VFE next, when you select the flap and the surfaces move, the A/THR will follow VLS down.
In the “normal” over weight checklist I get it, that you may have to disconnect as described, but the overweight flap/slats jammed fault case was different.
Would really appreciate your input.
Kind regards and Happy new year