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Hydraulic PTU.

And it's a robotic dog that is used for fire detection.
Seriously though, is it just running a self test or, what’s it doing? Because I’ve ridden in a lot of A3xx airplanes over the years, and I can’t recall hearing that noise in cruise.

but that might just be the ambient noise overpowering it.
 
Seriously though, is it just running a self test or, what’s it doing? Because I’ve ridden in a lot of A3xx airplanes over the years, and I can’t recall hearing that noise in cruise.

but that might just be the ambient noise overpowering it.
It only runs when the pressure difference between the Green HYD and Yellow HYD is >500 PSI. One system pressurizes the other. If you’re hearing it in cruise someone is having a crappy day.
It runs a self test during the second engine start, or if someone is taxiing around and forgot to turn on the yellow electric pump. Also usually at the gate after shutdown when the hydraulic pressure is dropping. Also usually during gear retraction until the pressures even out.
Edit: Should have clarified, if they’re taxiing around single engine.
 
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It only runs when the pressure difference between the Green HYD and Yellow HYD is >500 PSI. One system pressurizes the other. If you’re hearing it in cruise someone is having a crappy day.
It runs a self test during the second engine start, or if someone is taxiing around and forgot to turn on the yellow electric pump. Also usually at the gate after shutdown when the hydraulic pressure is dropping.
Thanks! Appreciate that!
 
So what is Flare Mode, and why does it exist vs just whatever Normal is?
Essentially “how do we make this feel normal because we have a stupid FBW system that feels like absolutely nothing so otherwise it would be unflyable.” Starts pitching down around 30ft to basically “trick” you into pulling up and flaring.
Can you tell I’m still not a fan of the bus?
 
Essentially “how do we make this feel normal because we have a stupid FBW system that feels like absolutely nothing so otherwise it would be unflyable.” Starts pitching down around 30ft to basically “trick” you into pulling up and flaring.
Can you tell I’m still not a fan of the bus?

That is actually pretty interesting… is there no feedback to the side stick at all? Also… how “tight” are the controls? Do they feel sluggish evenly throughout the flight, or are they snappy?

Something I’ve always wondered.
 
That is actually pretty interesting… is there no feedback to the side stick at all? Also… how “tight” are the controls? Do they feel sluggish evenly throughout the flight, or are they snappy?

Something I’ve always wondered.
That’s probably personal preference. It pretty much feels the same always, I’d say fairly tight and snappy, but since the roll control commands a roll rate, IMO gusty crosswind landings feel kind of odd. To me it feels ok when it’s smooth, but gives me weird “Dave & Buster’s arcade game” vibes. Not a huge fan of how it feels when it’s anything other than smooth, but I also complain a lot. I definitely prefer something with a little more feedback.
 
It's sensitively numb, and there's no trim, which is weird.

That’s remarkably strange. Like, if you hold the stick forward does it trim until when you let off that pitch angle is neutral?

Do all the variants fly the same because they’ve been programmed to fly that way?

From a user interface standpoint - do you like how it doesn’t have conventional trim and pressure? As an operator what (in the controls) do you wish was different?


Thanks for humoring my curiosity- literally the most advanced flight controls I ever actuated were hydraulic flaps and electric trim, so I’m kind of out of my element on this topic.
 
That’s remarkably strange. Like, if you hold the stick forward does it trim until when you let off that pitch angle is neutral?

Do all the variants fly the same because they’ve been programmed to fly that way?

From a user interface standpoint - do you like how it doesn’t have conventional trim and pressure? As an operator what (in the controls) do you wish was different?


Thanks for humoring my curiosity- literally the most advanced flight controls I ever actuated were hydraulic flaps and electric trim, so I’m kind of out of my element on this topic.
If you hold it forward (in normal law) you’re commanding less than 1G, so it’ll keep pitching over until you run into the pitch limit, and then you’ll get “I’m sorry, Dave, I’m afraid I can’t let you do that.”
To really dumb it down in most situations in any phase if you put the airplane in an attitude and let go of the stick, it’s going to stay exactly where you put it. Which of course in the real world never happens because of wind, bumps, etc. I’ll give my own answer and I’m curious to hear his and other Airbus pilots answers, but I don’t particularly care for it, I kind of miss the more conventional feel of… every other airplane I’ve flown. Not to be to “well, on the Embraer…” but the 175 while being FBW still very much to me felt more like an actual airplane in control inputs and still had actual trim. It’s fairly complex, but the theory is fairly easy to get once you understand it, and there’s a reason it’s usually covered fairly in depth in initial training and recurrent. But “getting it” and liking the actual feel of it are two different things.
 
Essentially “how do we make this feel normal because we have a stupid FBW system that feels like absolutely nothing so otherwise it would be unflyable.” Starts pitching down around 30ft to basically “trick” you into pulling up and flaring.
Can you tell I’m still not a fan of the bus?

Yeah and the way it pitches down is by inputting a nose down trim input forcing you to have to pull back on the stick to counteract the nose down trim so you have some positive feedback on the stick as you pull back and hold it back rather than if it didn’t trim down you would just pitch up to flare then stick back almost to neutral which does not feel natural at all. One thing we practiced a few times in the sim were going arounds of a balked landing. You have to hold a lot of stick back pressure to get the airplane climbing because you’re fighting that nose down trim while in direct law until it blends into normal law on climb out and auto trims it. It’s all weird. I probably didn’t explain some of it right, but it’s a unique airplane. Glad I got to fly it, but I’m glad to be back to flying airplanes with conventional flying user interface characteristics again.
 
Can you tell me why the 737 sucks so bad?
Money, capitalism, Southwest, American, and political corruption.

From a user interface standpoint - do you like how it doesn’t have conventional trim and pressure? As an operator what (in the controls) do you wish was different?
The only thing I would really change is tying the side sticks together such that moving one moved the other. That way, you know what the other pilot is asking of the airplane.

A little evil of this airplane is that if one pilot holds theirs full forward, and the other full aft, the system sums the inputs to zero, the airplane consequently holds 1 G, and French voice says “DUAL INPUT” and it’ll sit there until someone lets go or someone hits the takeover pushbutton. Completely opposite inputs equates to nothing, which might not be the most appropriate thing to do. Speaking of 1 G, even in alternate law, zero degrees of pitch command still commands 1 G.

I guess the other thing I’d do is have the thrust levers back-driven by autothrust inputs, too, so that you can simply and quickly override said inputs if need be.

As far as how it flies? It’s fine. It’s wonderfully boring and beautifully consistent, which is exactly what an aviation appliance like an airliner is supposed to be. I think people by and large overthink the flight controls too. If the airplane is dancing, it’s probably your inputs that are causing it. We have a sim instructor who, on a V1 cut, once you’ve rotated and the blend to flight mode completes, is fond of making you let go of the stick completely; the handling characteristics are downright boring with all of the magic working, and work it does.

You have to hold a lot of stick back pressure to get the airplane climbing because you’re fighting that nose down trim while in direct law until it blends into normal law on climb out and auto trims it. It’s all weird. I probably didn’t explain some of it right, but it’s a unique airplane.
Properly speaking, it’s still pitch normal until after weight on wheels, and the transition back to ground mode; the nose down trim increment provides a conventional flare feel but does not alter the basic function of the load factor demand.
 
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If you hold it forward (in normal law) you’re commanding less than 1G, so it’ll keep pitching over until you run into the pitch limit, and then you’ll get “I’m sorry, Dave, I’m afraid I can’t let you do that.”
To really dumb it down in most situations in any phase if you put the airplane in an attitude and let go of the stick, it’s going to stay exactly where you put it. Which of course in the real world never happens because of wind, bumps, etc. I’ll give my own answer and I’m curious to hear his and other Airbus pilots answers, but I don’t particularly care for it, I kind of miss the more conventional feel of… every other airplane I’ve flown. Not to be to “well, on the Embraer…” but the 175 while being FBW still very much to me felt more like an actual airplane in control inputs and still had actual trim. It’s fairly complex, but the theory is fairly easy to get once you understand it, and there’s a reason it’s usually covered fairly in depth in initial training and recurrent. But “getting it” and liking the actual feel of it are two different things.
The E-jet doesn’t provide any protections beyond angle of attack limiting, and even then a conventional stall warning with a conventional recovery was provided. I’m in no way trashing the way that airplane flew—it is also a very nice aviation appliance—but the Airbus approach is fundamentally different and much more aimed at protecting you from yourself and, by extension, the people in back. Granted, Airbus have walked back off the idiotproof nature of the airplane, as the universe tends to laugh and build better idiots.

By and large, however, Bernard was right.
 
That’s remarkably strange. Like, if you hold the stick forward does it trim until when you let off that pitch angle is neutral?

Do all the variants fly the same because they’ve been programmed to fly that way?

From a user interface standpoint - do you like how it doesn’t have conventional trim and pressure? As an operator what (in the controls) do you wish was different?


Thanks for humoring my curiosity- literally the most advanced flight controls I ever actuated were hydraulic flaps and electric trim, so I’m kind of out of my element on this topic.

I raged pretty hard against the Airbus when I showed up on it, maybe for the first year. Eventually I learned that she's like a French mistress; do whatever she wants, and she'll keep you happy.

Biggest difference is weight. Otherwise they mostly fly the same with a few minor differences. @Adler is right, she's perfectly trimmed at all times, and always straight.

It's just very numb feeling.
 
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