Dash8 question

[rchcfi]

This is for all you Dash8 drivers out there concerning the spoilers.

I used to work at SEA where Horizon had what seemed like 1 million Dash8s departing every day. I noticed that just before lining up, the spoilers would deploy and stay in the full up position until take-off power was applied. From my limited experience with those jet engine powered flying things, why is this? I know most jets have the auto spoiler which deploys upon wheel contact with the runway after it is set as such in the cockpit. Did DeHavilland incorporate this "switch" so that whenever the aircraft is at a predetermined configuration and weight is on the wheels they deploy? And does that same "switch" differentiate between power settings so that they automatically stow upon application of takeoff power? Or am I just reading way too much into this?

 

[xjcaptain]

You're right on track. The Dash8-100's that we flew had a flight-ground switch for the spoilers. Whenever the aircraft has weight on wheels and the power levers retarded the spoilers would deploy. (The ground spoilers would deploy with weight on the main wheels, and the roll spoilers would switch to ground mode (all up) when there was weight on the nose-wheel.) A switch was provided to override the weight on wheels function so you don't taxi around with the spoilers up (and have the possibility of fod/ice etc under the spoiler panels). There are two ground spoilers and two roll spoilers on each wing for 8 total. Just prior to taking the runway our procedure was to switch the spoilers back to flight mode so they would pop up as we took the runway. As you noticed as soon as the take-off begins the spoilers come back down. This is because when the power levers are advanced the spoilers are automatically retracted so you can't accidentally take-off with the spoilers up or in the case of a go-around after touching down. Even if the switch is left in ground mode by mistake (that never happens!!) it doesn't matter because it is a magnetically held switch that is automatically released when the power levers are advanced. I hope this answers your questions.

 

[rchcfi]

I guess the reason I asked the question was the concern for the probability of the spoilers not retracting as takeoff is commenced. It just seemed to me that one airplane designed with that feature out of the other 50 on the market would lead to some questions concerning the possibility of the disasterous consequences. While living up there in SEA I would also go to Boeing Field to check out the nice and shiny pretty painted new Boeings. One day I watched a 737-700 getting ready for a test flight. He did his obligatory before takeoff check and the left outboard spoiler remained deployed as he applied power for takeoff. Naturally I was concerned as the takeoff roll continued and the spoiler remained deployed. As soon as he broke ground the left wing dropped significantly and I could see the immediate input of opposite aileron just to keep the aircraft from not scraping the left engine on the asphalt. And that was from just the outboard spoiler. If all the flight and ground spoilers on that wing would have been deployed, I'm afraid to think of what might happened. Needless to say, he requested an immediate return and landed without incident. Well, probably an incident in his shorts, but other than that the aircraft was alright.

 

[sayagain?]

I'm dusting the cobwebs from my memery but I believe that you should get the take-off warning horn if any spoilers are not retracted on T/O.

sayagain?

 

[xjcaptain]

Cobwebs or not you are correct. Ocassionally when flying with a real throttle jockey, you would get the config warning for a split second on take-off. If the perosn would really shove the power levers forward quickly, you would hit the 64 degree switch in the power quadrant before the spoilers would have time to full retract. With a normal power application on take-off the spoilers are down well before you get to that position on the power levers.

 

[B1900DFO]

On the captains side there is a guage which indicates the position of the spoilers. One of the duties of the non-flying pilot during the takeoff roll is to ensure that the spoilers retract after advancing the power levers. Quite a few things would have to go wrong in order to takeoff with the spoilers deployed.

 

[Freight Dog]

Well, that depends on your company SOP's. Part of our takeoff checklist calls for captain to insure that Flight/Taxi switch is position to Flight which arms the spoilers and with power levers in ground beta range the spoilers will be deployed until you advance the power levers. Once you advance the power levers, the spoilers will retract.

After landing, you bring the flight/taxi switch to taxi and that retracts the spoilers on the ground.


By the way, does any other DHC-8 operator have ground roll spoilers deactivated?

 

[Singlecoil]

The reason there is a magnetic switch in the Flight/Taxi switch, is that it was designed to flip to the flight mode when the power levers are advanced. It exists to retract the spoilers after the aircraft has landed. For some reason, most operators think we need to extend the spoilers immediately before takeoff only to see them retract again as power is applied, as if we need to verify their function, because we all know Dash-8's use tons of runway.
How about that fire handle and autofeather system? On takeoff if you have a fire, the plane is designed in such a manner that all you have to do is pull the fire handle. Fuel and hydraulics will be shut off, the engine will feather (if autofeather was armed) and life will be good. But some operators insist on extra steps just in case other systems happen to fail at the same time. I've heard that an operator in Hawaii says you can't takeoff or land with the yaw dampner engaged. Also totally bogus.

 

[chperplt]

I've heard that an operator in Hawaii says you can't takeoff or land with the yaw dampner engaged. Also totally bogus.

How does the yaw damp work in the Dash? On the Beech you have no peddle movement with yaw damp on. Not a very good thing on takeoff or landing.

 

[sayagain?]

You have plenty of peddle movement with the yaw damper on and especially off. Try flying the Dash on a windy day with an inop yaw damper. No fun whats so ever!

sayagain?