A319 - Squirrely on takeoff?

CJones

CJones

Final Approach
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I've (unfortunately) been travelling quite a bit for work far this year. My trips are regional flights mostly on MD-80s and A319/320s.

It it just me or are the A319s a little squirrely on takeoff? It seems like they bounce back and forth from side-load to side-load on the takeoff roll. At first I thought it was just crosswind on takeoff, but I've flown enough times over a short period of time that it seems like a trend for the A319.

Anybody with experience in the nose of these things to comment?
 
CJones said:
I've (unfortunately) been travelling quite a bit for work far this year. My trips are regional flights mostly on MD-80s and A319/320s.

It it just me or are the A319s a little squirrely on takeoff? It seems like they bounce back and forth from side-load to side-load on the takeoff roll. At first I thought it was just crosswind on takeoff, but I've flown enough times over a short period of time that it seems like a trend for the A319.

Anybody with experience in the nose of these things to comment?
Click to expand...

Interesting you mention it, I have also noticed them 'rocking' around on their gear.
 
I have observed (from the back) what seems to be more noticeable yaw coupling in turbulence. Maybe related.
 
CJones said:
I've (unfortunately) been travelling quite a bit for work far this year. My trips are regional flights mostly on MD-80s and A319/320s.

It it just me or are the A319s a little squirrely on takeoff? It seems like they bounce back and forth from side-load to side-load on the takeoff roll. At first I thought it was just crosswind on takeoff, but I've flown enough times over a short period of time that it seems like a trend for the A319.

Anybody with experience in the nose of these things to comment?
Click to expand...

Never noticed it.:dunno:

Doesn't mean the PF isn't "walking the rudder" on TO roll, but I've seen that on other types.
 
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Never noticed it either, but it's been years since I've flown it.
 
It's pretty pronounced on a long take-off roll like at Denver...
 
I have noticed this as well. The last type I was in was a 321 and somewhere near the back (maybe 3/4's way).
 
Lindberg said:
I have observed (from the back) what seems to be more noticeable yaw coupling in turbulence. Maybe related.
Click to expand...

I've noticed this myself a few times on both America West (may they rest in he!!) and Jet Blue.
 
It seems like it's not noticed up front, over the wing it's pretty pronounced. It feels like there is a bunch of slack in the gear and it bounces back and forth against the limits as it makes its way down the runway.

I always wondered if it was for, or due to, those cross wind landings where they touch down in a crab.:dunno:
 
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Nope. THis is just a sign that you have a ****ty pilot. Cheers :)
 
Henning said:
It seems like it's not noticed up front, over the wing it's pretty pronounced. It feels like there is a bunch of slack in the gear and it bounces back and forth against the limits as it makes its way down the runway.

I always wondered if it was for, or due to, those cross wind landings where they touch down in a crab.:dunno:
Click to expand...

What I've noticed is in the air in turbulence, not so much on the ground. Is the rudder system on the 319/320 FBW?
 
Fearless Tower said:
Isn't the gear higher than say a 737? A319/320s always look like they are a bit higher off the ground. Perhaps the higher CG amplifies poor pilot technique?
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Yes the gear is higher. It's about pilot technique. These guys are apparently "walking the rudder" on take off roll. This was even briefed and in the FCTM back in the 727 days.

FWIW, the 75/76 also sit high on the gear.

Jeff Oslick said:
What I've noticed is in the air in turbulence, not so much on the ground. Is the rudder system on the 319/320 FBW?
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Rudder is controlled by cables and hydraulics as well as computers for the yaw dampers.

The nose wheel steering is electric (same for the brakes). Move the rudder or nose wheel tiller and you are sending an electronic command through the NWSC to the actuator on the nose gear to steer it. It's actually a very smooth system.
 
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Henning said:
It seems like it's not noticed up front, over the wing it's pretty pronounced. It feels like there is a bunch of slack in the gear and it bounces back and forth against the limits as it makes its way down the runway.

I always wondered if it was for, or due to, those cross wind landings where they touch down in a crab.:dunno:
Click to expand...

No. :nonod:
 
Glad I'm not the only one who has noticed it. I hadn't thought about the longer gear legs amplifying the issue if poor pilot technique.

Sounds like these guys need some time in a Cub with a crotchety old CFI berating them from the rear seat.
 
CJones said:
Glad I'm not the only one who has noticed it. I hadn't thought about the longer gear legs amplifying the issue if poor pilot technique.

Sounds like these guys need some time in a Cub with a crotchety old CFI berating them from the rear seat.
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They need some time in the cockpit with an Instructor to teach them correct techniques and avoid "walking the rudder".
 
RotorAndWing said:
Move the rudder or nose wheel tiller and you are sending an electronic command through the NWSC to the actuator on the nose gear to steer it. It's actually a very smooth system.
Click to expand...

Ok, so a question on how this works. I know you use the tiller for taxi speeds and maneuvering on the apron, and the tiller is the device to the left of the stick marked with "pedal disk", correct?

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But say on the takeoff roll on a crosswind day, does the rudder pedal also control the nosewheel until the rudder is effective? If so is there some switch that you activate after you line up on the runway or something that is automatically activated at some ground speed? Just curious.
 
RotorAndWing said:
They need some time in the cockpit with an Instructor to teach them correct techniques and avoid "walking the rudder".
Click to expand...

I gotta ask, what was the theory behind "walking the rudder"? What issue is it addressing?
 
RotorAndWing said:
...

Rudder is controlled by cables and hydraulics as well as computers for the yaw dampers.

...
Click to expand...

Isn't the rudder (being mechanically connected) and pitch trim (also mechanically connected) the last line of defense, so to speak, in case of full computer meltdown in the Airbii?

(Not that I can fathom that occurring, but it is nice to know there are mechanical options if SHTF)
 
SCCutler said:
Isn't the rudder (being mechanically connected) and pitch trim (also mechanically connected) the last line of defense, so to speak, in case of full computer meltdown in the Airbii?

(Not that I can fathom that occurring, but it is nice to know there are mechanical options if SHTF)
Click to expand...

That brings up an interesting question when one considers Souix City. What type of redundancy/reversions to the throttles are there?
 
Henning said:
That brings up an interesting question when one considers Souix City. What type of redundancy/reversions to the throttles are there?
Click to expand...

Good question.

Sure wish the DC-10 had had mechanical... something. Thank God for Denny Fitch!
 
Bill Jennings said:
Ok, so a question on how this works. I know you use the tiller for taxi speeds and maneuvering on the apron, and the tiller is the device to the left of the stick marked with "pedal disk", correct?


But say on the takeoff roll on a crosswind day, does the rudder pedal also control the nosewheel until the rudder is effective? If so is there some switch that you activate after you line up on the runway or something that is automatically activated at some ground speed? Just curious.
Click to expand...

You can use either tiller or rudder pedals to steer. The tiller gives you more authority (left and right) for ramp maneuvers and the rudder pedals have limited nose wheel travel ( for TO and Landing). There is no switch to switch between them. The "pedal disc" you see on the tiller is a switch you push down with your palm to disconnect the rudder pedals from steering while you do a control check on the rudder (full left and right)

On a crosswind TO the rudder pedal steering has enough authority to steer the nose wheel until the rudder takes over.
 
Henning said:
I gotta ask, what was the theory behind "walking the rudder"? What issue is it addressing?
Click to expand...

A pilot will start walking the rudder on TO ( or landing) when he is over correcting. The airplane will make a small deviation left or right and the pilot applies too much rudder input to correct, hence the plane corrects to far in the opposite direction, he makes an over correction in the opposite direction and exacerbates the situation.
 
I've experienced this and it's more pronounced the farther aft you're sitting. I usually sit near the front and don't feel it up there.

I'll be sitting in row 2 on a 319 tomorrow, launching out of Denver. I'll see if I notice anything.
 
SCCutler said:
Isn't the rudder (being mechanically connected) and pitch trim (also mechanically connected) the last line of defense, so to speak, in case of full computer meltdown in the Airbii?

(Not that I can fathom that occurring, but it is nice to know there are mechanical options if SHTF)
Click to expand...

The rudder is mechanical (cables) and the THS (trim able horizontal stabilizer) is hydraulic. There are 3 hydraulic systems, 2 electric hydraulic pumps, 2 engine hydraulic pumps and a RAT that has a hydraulic pump attached to drive the hydraulics or emergency generator. The hydraulics have a " stand pipe" in case of a leak to prevent total loss of fluid.

In the event of "direct law" (really bad day) the gear can be dropped via gravity and the rudder reverts to cable, and pitch can be controlled with the remaining hydraulics using the THS.

This is practiced and taught in the sim. It's not pretty, but the plane is controllable and can be landed.







Henning said:
That brings up an interesting question when one considers Souix City. What type of redundancy/reversions to the throttles are there?
Click to expand...

The engines have no cable control, total electric. Each engine has a FADEC and the FADEC's cross talk to each other constantly. In the event of a total electrical failure ( unlikely) each FADEC has a PMA ( permanent magnet alternator) that will power it from the engine accessory case.
 
RotorAndWing said:
The rudder is mechanical (cables) and the THS (trim able horizontal stabilizer) is hydraulic. There are 3 hydraulic systems, 2 electric hydraulic pumps, 2 engine hydraulic pumps and a RAT that has a hydraulic pump attached to drive the hydraulics or emergency generator. The hydraulics have a " stand pipe" in case of a leak to prevent total loss of fluid.

In the event of "direct law" (really bad day) the gear can be dropped via gravity and the rudder reverts to cable, and pitch can be controlled with the remaining hydraulics using the THS.

This is practiced and taught in the sim. It's not pretty, but the plane is controllable and can be landed.









The engines have no cable control, total electric. Each engine has a FADEC and the FADEC's cross talk to each other constantly. In the event of a total electrical failure ( unlikely) each FADEC has a PMA ( permanent magnet alternator) that will power it from the engine accessory case.
Click to expand...


So the throttle system is linked to, but not dependent on, the rest of the computers? IOW, there's multiple independent signal sources to drive the servos.
 
Henning said:
So the throttle system is linked to, but not dependent on, the rest of the computers? IOW, there's multiple independent signal sources to drive the servos.
Click to expand...

That's a basic way of explaining it. In managed mode with auto thrust engaged the FMGS via the FMS gives commands to the FADEC's. In select mode with auto thrust engaged the pilot selects speed and the FMGS tells the FADECs what to do.

In select mode with auto thrust disengaged the pilot can use the thrust levers to set throttle position.
 
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RotorAndWing said:
That's a basic way of explaining it. In managed mode with auto thrust engaged the FMGS gives commands to the FADEC's. In select mode with auto thrust engaged the pilot selects speed and the FMGS tells the FADECs what to do.

In select mode with auto thrust disengaged the pilot can use the thrust levers to set throttle position.
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That works. If the problem makes its way all the way to the servo end, there's no real difference in how the system works, there's not a damned thing to do when it fails.:lol:
 
RotorAndWing said:
A pilot will start walking the rudder on TO ( or landing) when he is over correcting. The airplane will make a small deviation left or right and the pilot applies too much rudder input to correct, hence the plane corrects to far in the opposite direction, he makes an over correction in the opposite direction and exacerbates the situation.
Click to expand...

I've felt this on several flights on an ERJ-145. Never been on an A319.
 
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