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manuel ortiz
11th Mar 2002, 00:10
If his previous Q. was too easy and you have already answered it feel free to continue..... Here's another one , Cheers !. .. .--------------. .. .START FORWARDING .... .. .There have been a number of threads regarding the pitch up characteristic of the Airbus 320 series during ground spoiler deployment when landing. Recently, I heard of an elevator precommand that occurs when the ground spoilers extend. For the 320 this happens during manual flight only. For the 319 and the 321, it happens during both autolands and hand flown landings. Could this feature of the flight control system explain some of the pitch ups during touchdowns that have been experienced by some of the pilots on this forum?. . . .Also it was explained that on the 320 there is a pitch precommand with speedbrake deployment to reduced the pitch effect when the speedbrake is deployed in flight. Does anyone know why this is not on the 319 or 321?. . . .Can anyone explain more about the nature of these pitch precommands?. .. .END

Iceman49
11th Mar 2002, 00:44
I've never heard of any precommand pitch up...but there is a push over command that happens around 50feet RA...that is to allow you to have a normal flare feeling. I think part of the problem on touch down, is that the pilots try a continous flare. Its better to pick a pitch attitude (5-6deg) and hold it. Additionally try to derotate the pitch at touchdown to counter the pitch up caused by the spoilers. The 319 works the same way.. . . . <small>[ 10 March 2002, 19:45: Message edited by: Iceman49 ]</small>

manuel ortiz
12th Mar 2002, 08:01
Tks Iceman ,. .. .Actally from what I have read this FBW systems do inject a pre command pitch demand directly to the elevators in order to have more stable pitch attitude in flight when spoilers or speedbrakes extend.. .I do not have any details for all this after touch dawn. . .Rest of what you said I basically agree , the FCOM's have quite good info on that and I am sure the person making the Q. has gone trough them in very much detail for all this.. .Tks again.

javelin
13th Mar 2002, 05:27
This topic opens a few points to discuss. The 320 and 321 have different characteristics. These airplanes even differ with a change of engine. A V2500 will behave differently to a CFM, especially during autoland, the thrust off is different, the flare is different and I believe that this may be a contributary cause of some of the tailstrikes which have happened recently. Watch how the airplane autolands, watch where it touches down and how the spoiler activation pitch up affects the landing. Personally I prefer a CFM 321, it has better takeoff performance than a V2500-A1 320, it autolands better and still is fun to fly.

A340Driver
14th Mar 2002, 08:23
Hi Manuel,. .If I recall from my A320 days there was an OEB (a long time ago) regarding pitch up during landing I believe it stated 7 degrees was the limit before the pilot had to apply stick down to counteract the nose up. I believe it was fixed with a latter mod.. . . . <small>[ 14 March 2002, 03:24: Message edited by: A340Driver ]</small>