View Full Version : A320: The max speed of THS trim control wheel

7th Oct 2009, 16:06
Just want to know the speed limit for the THS trim wheel. Since the max trim rate is 2 deg/s when 2 systems are operating. from the position ratio of 1/2.13, the max wheel speed is only 0.93 deg/s. Is this correct?

Thanks in advance!

7th Oct 2009, 16:07
I'm not being flippant - I'm genuinely intrigued: why do you want to know that?


7th Oct 2009, 16:18
I'm not being curious, just serious paranoid, hehe. :}

7th Oct 2009, 17:23
The speed limit is VMO/MMO......

7th Oct 2009, 20:10
The A320 doesn't have a trim wheel. It's FBW

7th Oct 2009, 20:16
Eh? It still has a trim wheel man, I'm quite sure I saw one last time i sat in one?

Lacking a better picture, here is proof:


Never mind that, what are you asking precisely? The maximum turn rate of the wheel itself, the maximum automatic trim rate on the stabilizer?

Edit: Just checked in the FCOM 2, couldn't find anything that detailed about it unfortunately - may i ask how your paranoia comes into play here? ;)

7th Oct 2009, 23:16
The A320 doesn't have a trim wheel. It's FBW

He said a320, not the triple 7!!

8th Oct 2009, 08:51
The A320 THS system is roughly 18 trim wheel turns for 17.5 degrees of Stab movement

8th Oct 2009, 15:27
Thanks for trying to answer my question! I'm asking the max wheel speed, not the trim rate. I did the calculation from the info I have and it just seems pretty slow, so I would like to as anyone can confirm it.

The word paranoid was response to the post of 1234, nothing to do with the question itself. He was so troubled by the fact that I'm asking such a question:)

BTW, it a nice picture, which I happened to look at it too yesterday. That page is a pretty good introduction for basic facts of A320 EFCS.

Nice day!

8th Oct 2009, 15:33
last post was for STBYRUD and this one is for 777: (http://www.pprune.org/members/308120-stbyrud)

Thanks for both of you guys! However, the number in your post is pretty much halve the ratio (0.97) of (pitch angle / wheel turn) comparing with my calculation (2.13). So it is A320 we are talking about, is it?


8th Oct 2009, 15:51
Alright I see ;) Well, if you want more info on the topic, I can't unfortunately point you to a source for the actual FCOM, but in case you don't know the web site yet, check out SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com), specifically SmartCockpit - Airbus 320 Series (http://www.smartcockpit.com/plane/airbus/A320/)

Have a good one,

8th Oct 2009, 22:15
there is a test that the ths resets to 0 from full up and full down position. it definetly turns faster than 0.93deg/sec. what the exact value is though.. no idea

Swedish Steve
10th Oct 2009, 20:30
There is no speed limit, you can turn it as fast as you want. the speed the stab moves is controlled by the hyd motors that turn the screw jack. I suppose that if you can spin the wheel fast, you can keep up with the motors, but i haven't ever tried.

12th Oct 2009, 22:24
Just watch your fingers, and the other bloke's!

20th Oct 2009, 16:38
I also feel it's a bit of slow, but that's what I got from the system description document from Airbus directly.

One Outsider
20th Oct 2009, 16:47
What 'system description document'?

If would life so much easier if you just came clean and told us that you are working on a cardboard MSFS version.

20th Oct 2009, 19:04
Exactly my thought :D Why on earth would someone want to know otherwise? :ok: