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Fighting a pusher on the Q400

JimmyKool

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Never flew a Q400 but if its anything like the CRJ the pusher is designed for a high-altitude stall recovery. At low altitude if you over ride it with the AP/SP disconnect switch and hold it in you can actually use the little bit of Alpha margin left to recover from a stall. Its not something trained but I did it in the sim years ago. If you actually try to recover low altitude (with the pusher activated) without pushing and holding the AP/SP button you will not recover before hitting the ground. Any Q400 pilot's chime in.....or maybe give it a shot in the sim. Please no self proclaimed performance experts....
 

Raskal

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Just curious, I don't fly either type, but aren't all pushers certified for 80lbs or so of force so as to be manually over-ridden if necessary?
 

Salukipilot4590

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Maybe I didn't pull hard enough in the ERJ sim but it was quite forceful.
 

CX880

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Maybe I didn't pull hard enough in the ERJ sim but it was quite forceful.

LOL, the erj. In the sim, if you pull hard enough on the yoke, it's possible for the yoke to buckle and it will reset the sim to it's original position. We had a runway trim and I caught it it pretty late, as we were going down I pulled as hard as I could, the yoke buckled and the sim reset. I thought I just broke a 20mil sim. I guess it's a saftey measure designed so you don't actually break the yoke.
 

Salukipilot4590

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LOL, the erj. In the sim, if you pull hard enough on the yoke, it's possible for the yoke to buckle and it will reset the sim to it's original position. We had a runway trim and I caught it it pretty late, as we were going down I pulled as hard as I could, the yoke buckled and the sim reset. I thought I just broke a 20mil sim. I guess it's a saftey measure designed so you don't actually break the yoke.

You are totally not alone man! About sim three or four my sim instructor (GE) gave both my partner and I an ail. runaway...needless to say I reset the sim after locking my arm trying to stay level.
 

Striptyler

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The pusher is either manually over ridden, or disengaged via switch light on the glareshield. System is automatically disabled above 200kts, less than 250ft agl or anytime a partial or total failure of the stall protection or pitot anti ice has failed.
 

SpauldingSmails

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I heard you can override it by first pushing the power levers forward once the stick shaker starts.
 

DeucesWild

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Why is everyone talking about ways to override the pusher?? It is trying to save your life!
 

JimmyKool

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Not so much. As you approach a stall the pushers I'm familiar with will go full forward on the yoke. Great for High altitude but not when your Low. All the transport category a/c I've flown (only 3) have required a very small yoke movement or pitch change to avoid a stall. If your in this recovery process but the pusher trips your first instinct is to pull the yoke back to the proper recovery position. It again pushes forward, you pull back, and you have now entered a full accelerated stall that may not be recoverable with the altitude leftover. If you have been trained to disable the pusher (which I don't think anyone is) and have the almost inhuman ability to do it you could recover from an imminent stall with only soiled pants.
 

DeucesWild

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I disagree. The pusher is there for a reason. The shaker warns of an impending stall. If no corrective action corrects the problem, and a stall is immenent, then the pusher activates. The pusher is doing what is necessary to get the airplane flying again. Overriding the pusher or yanking on the yoke is only going to aggravate the problem. Proper stall recovery is to move the yoke Forward - Period. (Even if 200-300 ft is sacraficed).

I know that most airlines train the stall recovery (after shaker activation) to be done with no altitude loss. With late reaction or sudden yoke movement the pusher will activate. I believe the tendency for some to yank the yoke back is based on fear of 'failing' the manuever (plus or minus 100 ft.). The fear should really be of allowing the airplane to stall.

I believe that the airlines should be training realistic stall recovery after activation of the pusher, and that is moving the yoke Forward - even if altitude is lost. Zero altitude loss is realistic with just the shaker, but if the pusher ever activates, the yoke MUST be moved forward.
 

JimmyKool

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I agree with most of what your saying but the pusher I'm familiar with will activate early like the shaker. You should have a little alpha left to recover before the stall once the first push and you pull back while disabling the pusher you may be able to recover with altitude loss as you said. However, if you pull back again from a second push without disabling your probably in an accelerated stall. Try it in the sim if you can. I guess it depends on the a/c as well. I can just see all this happening in Buffalo which was may interest in the Q400 pusher system.
 

DeucesWild

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JimmyCool - you are arguing that the proper reaction to a pusher event is to pull back on the yoke. That is simply INCORRECT. I presume you are still referencing your experience in the CRJ. The PROPER recovery is to not ever get the pusher (only the shaker) and to have zero altitude loss. If you get the pusher you have already mucked up the manuever. The reason for this is sometimes late reaction, but most always is because you moved the yoke too quickly. Rate of movement in the wrong direction triggers the pusher. Pulling back quickly against the pusher only triggers another pusher. Another pull on the yoke, and you the pilot, has caused the stall.

If the pusher ever activates, you should NOT be pulling back. The pusher is correct and you are WRONG. At the point the pusher activates, your best chance may be to do nothing at all for 1 or 2 seconds. Let the airplane start flying again. Smoothly bring the A/C back to altitude, but don't fight the pusher or pull against it. Doing so will most likely seal your fate.

Your logic is flawed, but not uncommon. I believe the training we are receiving (because of fear of even 100 ft loss) is what is incorrectly conditioning some of us to pull back on the yoke at pusher activation. Think back to your primary flight training. When were you ever taught that the proper reaction to a stall, was to pull back on the yoke?

Accepting the altitude loss is MUCH preferable to stalling the airplane. We do have the ASAP program.
 

ReverseSensing

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Is stick pusher ever inhibited by system logic in the Q400?

At or above 215 kcas
Altitude great than 500 AGL

Other misc. items:

Stick pusher activation requires 2 independent signals from 2 separate stall protection modules.

For stick pusher, the SPMs look at:

AOA (averaged from two AOA vanes; pusher will not operate if either AOA transducer fails or there is a substantial difference between the two transducers.)
Flap position
Airspeed
Power lever angle
Condition lever angle
Icing status (as determined by the position of REF SPEEDS switch.

AP is disengaged at stick shaker (approx. 1.1 vso) and pusher fires at approx 1.05 vso.

Pusher can be overpowered (approx. 80 lbs. force) or turned off in response to a malfunction with a push off switch on the glareshield.

I could not find any documentation about how much the REF SPEEDS switch in the INCR position lowers the AOA calculated for shaker or pusher activation.

I could not find any documentation about whether the pusher is cancelled/overriden by advancing the power levers, but power lever angle is an input to the SPMs, so I suppose it's possible.
 
Last edited:

Farfugnügen

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Never flew a Q400 but if its anything like the CRJ the pusher is designed for a high-altitude stall recovery. At low altitude if you over ride it with the AP/SP disconnect switch and hold it in you can actually use the little bit of Alpha margin left to recover from a stall. Its not something trained but I did it in the sim years ago. If you actually try to recover low altitude (with the pusher activated) without pushing and holding the AP/SP button you will not recover before hitting the ground. Any Q400 pilot's chime in.....or maybe give it a shot in the sim. Please no self proclaimed performance experts....

In the CRJ sim training, I always held the AP/SP button at low altitudes during windshear/stall demos... you can't afford to have the pusher go off at 100' for any reason... if you ride the margin, you could get out of a situation where the pusher would have put you in the ground.
 

Raskal

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Why is everyone talking about ways to override the pusher?? It is trying to save your life!

Well, personally I wasn't advocating overriding the pusher I was just pointing out that it could be...

As for when you'd actually do that and if it would work, well, that's a different story. The only times I've been told to consider disarming the pusher is landing in windshear type conditions or a malfunction (mind you, the airline I'm at simply points at the disarm button and says if you hit it mx will have to come out, so don't hit it! End of incredible airline training.). As for anything else, if you're fighting the pusher then things are already pretty crappy-relax and let the pusher do its job and then recover.

People who get into arguments with the pusher in the sim are overreacting, too tense, or both.
 

JimmyKool

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In the CRJ sim training, I always held the AP/SP button at low altitudes during windshear/stall demos... you can't afford to have the pusher go off at 100' for any reason... if you ride the margin, you could get out of a situation where the pusher would have put you in the ground.


Yes...thanks. Exactly my point. Wondering if its possible in the Q-400.
 

ReverseSensing

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Yes...thanks. Exactly my point. Wondering if its possible in the Q-400.

Stick pusher in the Q400 will not go off below 500'. There is a switch light on the glareshield to disable it in the event of a malfunction. I don't know if any other combination of techniques, other than pulling to over-power it or flying out of it, will work.
 

surplus1

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Does anyone know if Colgan provides TOLD cards for this aircraft and, if so, do they include manuevering speeds related to bank angle?
 
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