Speed brake difference between A319/321 and 320.
 

Short but simple question:

Why is it that with the A319 and A321 you can pull full speedbrake with the A/P engaged. And with the A320 you can only deploy half speedbrake, so to deploy full speedbrake in the 320 you have to disengage the A/P.

Any idea why this difference is?


Cheers!

Hello
 

A320: The maximum speedbrake deflection in manual flight is:
40° for spoilers 3 and 4
20° for spoiler 2.
The maximum speedbrake deflection with the autopilot engaged is:
25° for spoilers 3 and 4
12.5° for spoilers 2.
A319: The maximum deflection for spoilers is:
25° for spoilers 3 and 4
12.5° for spoilers 2 in configuration 3, and 17.5° in other configuration
A321 dont know:O . Also the wing loading/load factor would diff for the two a/c. may be the autopilot cannot handle the associated loads of 40dg of spoilers:uhoh: anyone else care to clarify?

I think its to do with the flight software loaded. The A320 original software cannot cope with the trim changes etc associated with spoiler extension/retraction. I think A319/21 uses later software.

I believe it had to do with rapid decompression profile...originally you were able to get full speedbrakes with ap on with the 320. However during a rapid decompression senario when you deployed the spoilers at altitude coupled with the slow pitch over, the wings were loaded up and it would trigger a high aoa, retract the spoilers and produce a spoiler disagree message. So you would either have to reset the spoilers, or more than likely you would not notice them and trying to get down in a hurry without the spoilers. Additionally I believe that the full spoilers with ap on with the 319 is the same as half spoilers with ap on with the 320.

Funny how essential facts are subject of discussion.

Please don't get me wrong. Used to be also a busdriver in the greyshade.........

Pander...look at gear pins reply and spoiler deflection ..the 319 and 320 are the same=max deflection(A/P on A320..A/P on or off on the 319).....difference is with the Auto pilot off on the 320 you can get up to 40 ....if you take the A/P off the 319 you still only get 25.......sounds a little confusing but from what Ive been told it is only a design feature