i have a dhc-8 question

[baxters]

when a roll disconnect is initiated because of a roll spoiler jam which pilots control signals the splr switch light "on" so that the splr can be retracted?

 

[Catbird]

Capt's Yoke Thingy.

 

[Singlecoil]

It's been a couple of years, but if you have a roll spoiler stuck up, the yoke won't be jammed, and you wouldn't pull the roll disconnect handle. The case you are describing would be a roll control malfunction. I think the checklist would have you hold wings level with the yoke (duh), push the spoiler 1 or spoiler 2 switchlights if illuminated thereby relieving hydraulic pressure from the bad spoiler, and continue on your merry way.

In a roll control jam, either the Captain's or FO's yoke, or the ailerons are jammed. Pull the handle, then whichever yoke is free is used to control roll. If it is the Captain's, you are using ailerons, if the FO's, you are using roll spoilers.

 

[91100 100 set]

From the big Dash-8 manual I got in training at ALG:

"A roll spoiler cable curcuit jam, necessitating operation of the ROLL DISC handle to control the aircraft by ailerons alone, may result in partially extended roll spoilers if the jam occured during a roll input. The resulting counteracting aileron input necessary to control the aircraft will illuminate both SPLR switch lights (via an underfloor limit switch) if aileron travel exceeds 50 degrees of control wheel displacement from neutral. The switchlights must then be immediately pressed to retract the spoilers and restore symmetrical aileron control".

At ALG, a "roll jam" was a memory item, however the only action was to pull the handle. Pressing any illuminated switchlights was NOT a memory item, but I am sure that the appropriate abnormal checklist would direct you to do so.

Also, the aforementioned limit switch was only activated by movement of the FO's control wheel, as the captain's yoke only operated the spoilers (but of course they are normally operated together, allowing roll control via a mix of ailerons and spoilers).

 

[baxters]

It's been a couple of years, but if you have a roll spoiler stuck up, the yoke won't be jammed, and you wouldn't pull the roll disconnect handle. The case you are describing would be a roll control malfunction. I think the checklist would have you hold wings level with the yoke (duh), push the spoiler 1 or spoiler 2 switchlights if illuminated thereby relieving hydraulic pressure from the bad spoiler, and continue on your merry way.

In a roll control jam, either the Captain's or FO's yoke, or the ailerons are jammed. Pull the handle, then whichever yoke is free is used to control roll. If it is the Captain's, you are using ailerons, if the FO's, you are using roll spoilers.

this makes ultimate sense to me , however the schematic make up made none , and i'll tell u why ...i guess this is where i got confused becuase there is a line drawn from the f/o's control to the splr switch light saying "an electrical signal activated by limit switch (50 degreese of travel) with roll disconnect pulled...yuh see where im coming from?

 

[MW44]

The 50 degrees is important-

Lets assume you had to activate the roll disconnect due to a malfunction and after pulling the disconnect the captains control is stuck and the fo's is free. Remember once you split the controls the captain's yoke controls spoilers ONLY and the fo's is mechanically linked to the ailerons. Let's pretend that the roll spoilers jammed in a state where they are commanding a hard left turn. In this case, after splitting the controls, assume the fo's control wheel is free and to keep the airplane from rolling upside down the fo would naturally apply opposite or right aileron. As the fo applied more than 50 degrees of travel to keep the airplane level the logic would recognize that there is a serious problem and light up the SPLR switch. Pushing the switch deactivates the spoilers causing them to retract and normal flt is resumed with the fo controlling the airplane via ailerons.

One very important thing to remember is that if you have to pull the roll disconnect and the captains wheel is free (fo jammed) and the Splr switch lghts are illuminated do NOT push them. This would make the captains controls useless because you just deactivated the spoilers and the fo would still be jammed. It's been a while but I think that is a fairly accurate and long winded explanation.