speed brake - airbus
Moderator
Join Date: Apr 2004
Location: Rome
Posts: 792
Likes: 0
Received 0 Likes
on
0 Posts
Hi michelda,
the aim is to keep the AP engaged to avoid over controlling with all its associated issues (level busts in RVSM, speed falling below V alpha max, etc..). If the situation is recognised early enough the speed should stay below the protection limit and therefore you can benefit from the AP.
the aim is to keep the AP engaged to avoid over controlling with all its associated issues (level busts in RVSM, speed falling below V alpha max, etc..). If the situation is recognised early enough the speed should stay below the protection limit and therefore you can benefit from the AP.
Thread Starter
Join Date: Aug 2004
Location: italy
Posts: 163
Likes: 0
Received 0 Likes
on
0 Posts
Hi I 2021
You are absolutely right.
But there are two procedure....
One for prevent overspeed and one for recovery.
What do you think about the use of speed brake in the recovery one?
Thanks
You are absolutely right.
But there are two procedure....
One for prevent overspeed and one for recovery.
What do you think about the use of speed brake in the recovery one?
Thanks
Airbus says to extend them in case of overspeed.
Airbus says to select speed if speed variations occur around vmo / mmo.
Seems reasonable to me. They built it and flight tested it, presumably to speeds in excess of 0.82.
Airbus says to select speed if speed variations occur around vmo / mmo.
Seems reasonable to me. They built it and flight tested it, presumably to speeds in excess of 0.82.
Thread Starter
Join Date: Aug 2004
Location: italy
Posts: 163
Likes: 0
Received 0 Likes
on
0 Posts
Airbus says to use them but, in the limitation chapter, they are limited inside the envelope.
So do we use them outside the flight envelope?
For sure airbus tested them at speed above the maximum one but in this case we can flight faster than vmo or higher than max ceiling....
So do we use them outside the flight envelope?
For sure airbus tested them at speed above the maximum one but in this case we can flight faster than vmo or higher than max ceiling....
Join Date: Aug 2013
Location: Middle Europe
Posts: 80
Likes: 0
Received 0 Likes
on
0 Posts
since VMO/MMO exceedance is a precondition for an overspeed recovery, i suppose you're perfectly fine to use the speed brakes as part of the airbus standard procedure to recover from an overspeed condition. also VMO/MMO exceedance is not part of the speed brake inhibition logic. i assume airbus would have integrated this condition in the inhibition logic if it wasn't safe to use them during VMO/MMO exceedance.
i didn't find any limitation on the use of speed brakes in the limitation section of the FCOM (or maybe i'm just too tired already
).
i didn't find any limitation on the use of speed brakes in the limitation section of the FCOM (or maybe i'm just too tired already
).
Thread Starter
Join Date: Aug 2004
Location: italy
Posts: 163
Likes: 0
Received 0 Likes
on
0 Posts
as you said, i think it is logic to use speed brake during speed exceedance.
But with the wing at high speed and probably with some G force due to high speed protection, is it a good idea to extend spoiler for the wing structure?
In the limit part of the fcom it is reported that there is no limitation in speed for spoilers......for sure inside flight envelope. Outside envelope is a duty of test pilot to understand what is going on and not for a stupid pilot as me.
But with the wing at high speed and probably with some G force due to high speed protection, is it a good idea to extend spoiler for the wing structure?
In the limit part of the fcom it is reported that there is no limitation in speed for spoilers......for sure inside flight envelope. Outside envelope is a duty of test pilot to understand what is going on and not for a stupid pilot as me.
Outside envelope is a duty of test pilot to understand what is going on and not for a stupid pilot as me.
Join Date: Mar 2009
Location: EDDF - LIRF
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
If Airbus tested and published in the procedures (as it looks like in my manuals in both happenings approaching and exceeding VMO / MMO) this should not lead to personal aurguable judgment (even if based on some knowledge) that would bring only discussion in the cockpit in such a high workload and dynamic situation.
Otherwise we should start now to bring into the discussion the MACH divergence drag number and drop in Cl over Mcrit speed and we would not get out of it anymore.
I like to try to understand always the theory and principles behind any procedures, but as long as they fit and i´m in a healthy plane (not like the one of AF447) i would not willfully disregard any procedures that Airbus tested and reported.
Otherwise we should start now to bring into the discussion the MACH divergence drag number and drop in Cl over Mcrit speed and we would not get out of it anymore.
I like to try to understand always the theory and principles behind any procedures, but as long as they fit and i´m in a healthy plane (not like the one of AF447) i would not willfully disregard any procedures that Airbus tested and reported.
Join Date: Mar 2010
Location: The Home of the Gnomes
Posts: 412
Likes: 0
Received 3 Likes
on
2 Posts
Outside envelope is a duty of test pilot to understand what is going on and not for a stupid pilot as me.
What it does not mean is that the wings will come off at M0.83.
Join Date: Mar 2009
Location: EDDF - LIRF
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
Moreover load requirements during the certification phase prescribe a load of 2,5g up to VD, for the A320 family being M0,89 or VD 381kts..so we have a 31kts margin where i COULD pull up the load factor up to 2,5g without creating any structural faiuler or damage. (Offcourse i would not suggest it anyway !)
Per Ardua ad Astraeus
Join Date: Mar 2000
Location: UK
Posts: 18,579
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Tay Cough
What it does not mean is that the wings will come off at M0.83.
The clue, surely, is in the name SPEED brakes? There are also some levers that control the engines I believe.
If the jet cannot handle the 'excursion' without zoom climbing, then Mmo needs to be reduced for airline ops. Using altitude to wash off energy is for fighter pilots, not airline pilots - and they try to make sure the area is clear before they do so.
Thanks. I can't find it in Flysmart OLB or on Airbus world....
I've found other reference to the same document title on google, so it's not your company title.
I'll keep looking.
I've found other reference to the same document title on google, so it's not your company title.
I'll keep looking.
Found one! Courtesy of a copy of a Central American airline.
I cut and pasted your quoted paragraph into google.
Cheers, I can now sleep with the satisfaction of having learnt something today. :-)
I cut and pasted your quoted paragraph into google.
Cheers, I can now sleep with the satisfaction of having learnt something today. :-)
Per Ardua ad Astraeus
Join Date: Mar 2000
Location: UK
Posts: 18,579
Likes: 0
Received 0 Likes
on
0 Posts
Further to my post #15, I quote this (out of context, but extremely correct!) from the much berated Dozy on the 447 thread (post #739).
- delightfully simple, but maybe some prefer to leave it to the software engineers to sort out.
"What's it doing now"? Simple - it's nose-high and climbing. Best get the nose down and back to our cleared FL, then. No need to worry about laws, modes, or pushing buttons - just do the intuitive thing and the aircraft's systems will comply in a fairly transparent manner.