bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

How Do You Control The Ground Spoilers?

Fri Oct 11, 2002 1:17 am

Hi everyone. I would just like to know if there is a different stick used to activate the ground spoilers, or if the same speed brake handle is used. If they are the same, what determines when to deploy ground spoilers and when the speed brakes (or both at a time)?

I have known that quick descents are not uncommon, and that high descent rates can be achieved by the aircraft. I wanted to know if there are any limitations due to pressurization issues as to the descent speed. I once went into a 767 flight deck and noticed the VS pointing to the -4500 fpm, which I thought was rather high. Is it really?

Thanks in advance everyone.

-Alfredo
 
Guest

RE: How Do You Control The Ground Spoilers?

Fri Oct 11, 2002 1:24 am

Regarding spoilers....

In flight, the flight spoilers are activated by the speed brake handle. I know that Boeings have a spoiler mixer that activates them in proportion to the ailerons for better roll control.
Ground spoilers will only activate on the ground. They require weight on wheels via a squat switch or something similar. When arming the spoilers, normally one set (flight or ground) will deploy with the squat switch activation while the other set requires some sort of power input (such as reverse thrust).
 
avioniker
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Joined: Tue Jan 01, 2002 5:38 am

RE: How Do You Control The Ground Spoilers?

Fri Oct 11, 2002 1:40 am


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The ground spoilers are normally actuated using the spoiler handle. The handle is most normally located to the immediate left of the throttle levers. They may also be deployed on landing automatically through an electrical actuator connected to the control quadrant under the floor. On many aircraft there is an interlock so that the ground spoilers do not operate in flight or when the aircraft weight is not on the landing gear. The flight spoilers normally work through a mixing or proportioning mechanism to compliment the ailerons thus requiring less aileron deflection to achieve a higher roll rate. They deploy with the ground spoilers when the spoiler handle is pulled.
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: How Do You Control The Ground Spoilers?

Fri Oct 11, 2002 5:09 am

Depends upon the aircraft. Most utilize a single "speedbrake" or "spoiler" handle. Some of those have a "flight" limit position and some do not. Those that do "normally" utilize some form of physical restriction to prohibit movement beyond the flight limit when no weight on wheels is sensed. Notice the use of "some" and "normally." Naturally there are exceptions. i.e. F-100 uses "Lift Dumpers" which are "armed" by the pilots and activate with weight on wheels sensing.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: How Do You Control The Ground Spoilers?

Mon Oct 14, 2002 7:07 am

Thanks for answering my question everyone

-Alfredo
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: How Do You Control The Ground Spoilers?

Mon Oct 14, 2002 7:25 am

As AAR90 said, every aircraft is different and there will always be exceptions.

On the 767-300 for example, all six spoiler panels on each wing activate as both ground spoilers and roll control spoilers / speedbrakes..

On the 757, however, only the three outboard and two inboard spoilers act in this way, with all six operating on the ground.

In the latter case, the distiction between air and ground operation is achieved via the "air / ground logic system"
I used to love the smell of Jet-A in the morning...
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: How Do You Control The Ground Spoilers?

Mon Oct 14, 2002 8:54 am

Hi Rick767, thanks for responding. Since you fly the 767, do you know if there are any limits regarding descent rates? What would be considered a 'high' descent rate on the 767?
Thanks in advance

-Alfredo
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: How Do You Control The Ground Spoilers?

Mon Oct 14, 2002 12:54 pm

What would be considered a 'high' descent rate on the 767?

one where the flight attendants are pinned to the ceiling!!

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