Air India Airbus 319 Suspected Triple Hydraulic Failure

[Speed Freak]

Air India plane makes emergency landing in Pakistan - The Times of India (http://timesofindia.indiatimes.com/india/Air-India-plane-makes-emergency-landing-in-Pakistan/articleshow/14766088.cms)


Rumour has it that all 3 systems showed over heat. Possibly FWC going bonkers.

An earlier report had placed the aircraft registration as VT-SCG a relatively newer airbus 319 msn somewhere in th early 3000's.

[ironbutt57]

Air India flight makes emergency landing in Pakistan (http://thestar.com.my/news/story.asp%3Ffile%3D/2012/7/9/reutersworld/20120709151417%26sec%3Dreutersworld)
Wonder why they refused the offer to go inside?:ugh:

[Lonewolf_50]

The stories seem to interchangeably refer to the aircraft as A319 and A320.

??

Which is it?

[vivekh]

It's an A319.

AVherald reports it as a (single) hydraulic failure misreported by the Indian & Pakistani media as a triple hydraulic failure.

[CaptainProp]

You lose all three HYD systems you can bend over and kiss your @ss goodbye! :E

[BOAC]

So that's why they took away the control column.:O

[zerozero]

So that's why they took away the control column.

That is probably the funniest thing, and best Airbus joke, I've read on this site.

:)

[Yo767]

You lose all three HYD systems you can bend over and kiss your @ss goodbye!

Capt prop was definitely not flying the airplane in the link below:
DHL Aircraft Hit by Missile Over Baghdad Had Lost All Hydraulics (http://www.spacedaily.com/news/iraq-03a.html)

[Brookmans Park]

As I recall that was an A300B4 which is not FBW and has a nice big steering wheel were the meal tray goes on a" real areoplane"

[hetfield]

As I recall that was an A300B4 which is not FBW and has a nice big steering wheel were the meal tray goes on a" real areoplane" That "nice big steering wheel" is at little help if no hydraulic pressure at all.

In this case FBW or not doesn't matter.

Kind regards

Ex A300 driver

[CaptainProp]

@ Yo767 - I guess you weren't either as you seem to have gotten the aircrft types mixed up. :} Different aircraft, different story.

@ BP - Correct.

You lose 3 HYD systems on the A318/319/320/321 you are done.

[dixi188]

BPK,

You are right.

However when the DHL airbus was hit by a missile and all three hydraulic systems were lost the control column had no effect on the flight controls as there is no manual reversion, so a fly by wire aircraft would be in the same situation.
ie. Very limited control by use of engine thrust.

[Wee Weasley Welshman]

Every time I read the phrase 'Miracle on the Hudson' I think of the Baghdad Airbus incident. All engine out ditching was a piece of cake compared to that.


If it was an actual triple Hyd failure I'd expect some statement from Toulouse quite quickly. The reports in the Indian media are quite clear when they state 'they believe' all three systems failed. The lack of a smoking hole in the ground suggest their beliefs are misplaced.

[hetfield]

Every time I read the phrase 'Miracle on the Hudson' I think of the Baghdad Airbus incident. All engine out ditching was a piece of cake compared to that.Different story. Sully had to make just one decision within seconds. Thereafter IMHO it wasn't very demanding.

DHL was quite different. Many issues, like no flight controls at all, asymmetric lift/drag, no support from ECAM or even FCOM. But a little mor time to figure it out.

Just fly the aluminium to a safe end.

And they made it.

Still full of respect.

Retired A300 jockey

[Speed Freak]

Local warning on the over head panel and sd page indicating overheat on all three, however no warning generated by fwc. Faulty Sdac being blamed.

[Yo767]

CaptProp wrote: You lose 3 HYD systems on the A318/319/320/321 you are done.

Landing with 3 hydraulic systems failure was incorporated in our recurrent training program in my company after the DHL Baghdad incident. Since we were/are flying in sensitive areas (Irak, Kabul, Sudan, Yemen), the probability of being hit by a missile is greater than if you fly let's say in northern Canada. I and my colleagues have landed numerous times on A320, B767 and E190 (in the simulator of course) with the 3 hydraulic systems failure. After a little bit of practice, any pilot with a minimum of coordination can land on the pavement. So CaptProp, if one day you fly with a current or ex Gulfair pilot in the flight deck and we encounter this failure, while you kiss your arse goodbye, we'll be trying to land the airplane on the numbers.

[Zoso]

If you lose all three in an A320 you have to control the aircraft in pitch and yaw/roll with engine thrust like the Sioux City crash in '89.

[leftseatview]

THS (trimmable horizontal stabilizer) through trim wheel,and rudder mechanical backup are available in case of All hydraulic failure,or All flight control computer failure.Practiced in the SIM once in a while,not expected to happen in real life.

[KBPsen]

THS (trimmable horizontal stabilizer) through trim wheel,and rudder mechanical backup are available in case of All hydraulic failureNo, it is not. It must have been the Microsoft made simulator it was practised in, otherwise whoever teaches that should have their bottom smacked, severely.

[Earl of Rochester]

Air India Airbus 319 Suspected Triple Hydraulic Failure

Most unlikely.

[hetfield]

THS (trimmable horizontal stabilizer) through trim wheel,and rudder mechanical backup are available in case of All hydraulic failure

Sorry leftseatview,

but hopefully you are NOT in a LH seat of an airbus...:ouch:

[CaptainProp]

Landing with 3 hydraulic systems failure was incorporated in our recurrent training program in my company after the DHL Baghdad incident. Since we were/are flying in sensitive areas (Irak, Kabul, Sudan, Yemen), the probability of being hit by a missile is greater than if you fly let's say in northern Canada. I and my colleagues have landed numerous times on A320, B767 and E190 (in the simulator of course) with the 3 hydraulic systems failure. After a little bit of practice, any pilot with a minimum of coordination can land on the pavement. So CaptProp, if one day you fly with a current or ex Gulfair pilot in the flight deck and we encounter this failure, while you kiss your arse goodbye, we'll be trying to land the airplane on the numbers.

I will not say you can't do it, since I have never tried it myself, and you say you have, and on occasions even been successful in the simulator, but to come on here and say "while you kiss your arse goodbye, we'll be trying to land the airplane on the numbers" is just BS. That is not saying its not good to have tried it a couple of times, why not? Having said that.....

Did you try doing this in any sort of low-ish visibility? With any cross winds/gusty winds? From cruise down to landing? Prolonged flight in IMC? Actually flying an approach of some kind?

Or was it just from 10 nm final lined up with the "pavement" and CAVOK, in flight freeze and "Ok guys, are you ready? Then I'll un-freeze you and off you go lads!" ??

I would give the average crew 1 in 1000 to make it. On a good day.

Not referring to Yo767 here, but there are a lot of people around here, some even claiming to fly / know the airbus, making the most ridiculous comments about the airbus and its systems.

To clarify some things....

- Flight controls are Electrically-controlled and Hydraulically-activated.

- If you lose ALL electricity "MAN PITCH TRIM ONLY" will be displayed on the PFD and manual pitch trim (Mechanical control) of the THS is possible through the pitch trim wheel. This is called "Mechanical Backup" and has nothing to do with HYD systems.

- The Stabilizer is activated by Green or Yellow HYD pressure. If you have no HYD pressure at all, you will have no control of the THS. Referring to mechanical control of the THS there is a note in the FCOM stating "This function is inoperative, when the green or yellow hydraulic system is not pressurized"

- Rudder pedals gives the pilot MECHANICAL control of the rudder but the rudder is HYDRAULICALLY actuated via three independent hydraulic servojacks. In other words, if you have no HYD pressure you can not actuate the rudder.

[Phantom Driver]

Nice to hear someone talking some sense for a change.

[OK465]

If you lose ALL electricity "MAN PITCH TRIM ONLY" will be displayed on the PFD

You''ll need to write that on the PFD with an ink that glows in the dark. :}

[Fly3]

CaptainProp has it right on the money. I did my original training on the A320 with an Airbus test pilot some 20 years ago and he always made the point that without hydraulics you are screwed because the flight controls will not move. Although we did carry out approaches to land in the simulator there in mechanical back-up, thats with hydraulics but no Flight Control Computers, and it was doable, they emphasised that mechanical back-up was there to give time to recover at least one FCC. There are way to many armchair pilots on here!

[Wirbelsturm]

Tried this in the Sim a few years back. Managed to 'drain' all three systems to instigate the failure AFTER putting the gear down at about 15,000 feet.

As has been correctly stated before ALL flight controls are lost and the only means of flying the beastie is by thrust and aysemetric thrust.

A good brief (probably not going to happen if, God forbid, it ever happened for real!) and teamwork got us on the ground. It did take a few attempts mind you, something that real life wouldn't give you but, after a few tries it got progressivly easier to put it down on the airfield.

Not a problem though as, according to Toulouse, it can't ever, never, never, ever happen!:}

[Fly3]

One should be very wary of trying odd things in the simulator, such as no hydraulics flying. What the simulator does may have no resemblance to what the aircraft will do because no flight data was collected during the flight testing in order to programme the simulator correctly. The same applies to recoveries from unusual attitudes. Some trainers seem to think that they can place the aircraft in all sorts of weird positions and that the simulator will react like to aircraft. Not true, again because no data was gather during testing for these extreme situations and the simulator may not reflect what the aircraft will do. So be careful and don't be succored into thinking that if you can handle these things in the Simulator you will be OK in the aircraft. It just might bite you!

[swh]

No, they can be mechanically controlled, however they are hydraulically actuated. Have a look at the control schematic in the QRH, you can see the mechanical control connects to the hydraulic actuators.

This mechanical control is in place for the failure of the flight control computers. Electric control provided by the PRIM/SEC/FAC to the actuators, the mechanical control backs them up, it is designed to give enough control to get a computer reset and back online, it is not really designed for approach and landing as it is often misunderstood. It is not for a triple hydraulic system failure.

All in FCOM 1.

The A380 can be controlled wih the loss of the aircraft hydraulic system, as they have different actuators that have their own internal backup hydraulic system or electric motor to move the control surface.

[MACH082]

As has been correctly stated before ALL flight controls are lost and the only means of flying the beastie is by thrust and aysemetric thrust.
Ummmmm, well, something is deeply wrong here as every single trainer I have flown with has given me the perception that IT IS possible to control the aircraft with pitch trim and rudders in the event of a TRIPLE HYD failure.
Last edited by Superpilot; 14th Jul 2012 at 15:42.

I'm actually deeply concerned that you and your trainers believe this!

Heaven help us if you are actually flying the thing on the line somewhere and believe this!

What other gaping holes exist in your knowledge?

Just think about this logically.

No hydraulics = :{

[PBY]

The quality of airbus trainers could be another interesting thread. When I was doing my TRI in Germany, we were 5 captains. I was the only one who knew, that 3ple hydraulic means mechanical back up.
In our last QRH Airbus in its infinitive wisdom even took away the pitch and power setting for 3 degree glide path. The QRH tells you also to first level the wings in case of a stall and than recover from the stall.
I still think airbus is a superior airplane that produces inferior pilots. Boeing is the other way around. By the way I am an airbus guy, wishing to be a Boeing guy. Cannot deal with the training stupidity anymore. I see many guys in the sim with over 6000 hrs on airbus and they cannot fly basic pitch and power in this easy to fly airplane. When I train Boeing guys, it is not a problem after few minutes of getting used to the plane.
I am not sure if to blame the plane or airbus philosophy of training for this mess, but I suspect the second. How else you could have 3 pilots sitting in a stalled airplane for 3 minutes falling from over 30000 feet and not having a clue what is going on?

[vilas]

you are absolutely right. Many people misunderstand mechanical back up. It is not a back up for hydraulics but electrics. since this is FBW everythig is signalled electrically and you need something that moves without electrics for short time atleast.

[flydive1]

I'm actually deeply concerned that you and your trainers believe this!

Heaven help us if you are actually flying the thing on the line somewhere and believe this!

Why? What would change if he believe it or not in case of triple hydraulic failure?
The end result would probably be the same.

[CaptainProp]

@ PBY

....I was the only one who knew, that 3ple hydraulic means mechanical back up.

Was that a typo, or just me being too thick ( has happened before!:E ) to understand what you wrote?

From my previous post

- Flight controls are Electrically-controlled and Hydraulically-activated.

- If you lose ALL electricity "MAN PITCH TRIM ONLY" will be displayed on the PFD and manual pitch trim (Mechanical control) of the THS is possible through the pitch trim wheel. This is called "Mechanical Backup" and has nothing to do with HYD systems.

Hydraulic failure(-s) has nothing to do with mechanical backup, electrical failure does.

Why? What would change if he believe it or not in case of triple hydraulic failure?

He/she would know what was NOT an option anymore. Is it all of a sudden acceptable to have pilots NOT knowing the systems of the aircraft they fly? What else does he/she not know? What else are these "instructors" telling crew they can or can't do with this aircraft?

I've seen a very experienced airbus crew opening the X FEED valve when getting a fuel imbalance advisory 15 min after having an engine failure with damage. Pumped fuel over board and ran out of fuel on short final. 30+ years of airbus experience between the crew.

Another crew were getting a low on fuel with dual HYD failures and briefed that "Weather is not great so we will give it one go. If we can't get down we'll continue to our alternate" Checked fuel on FMS and were "happy" with their plan. Go around followed some minutes later by "Jeeesus, we are burning a lot of fuel....." Flying to their alternate with gear down and flaps jammed was not something they had calculated with... This was a very inexperienced crew though so hopefully it was a good learning experience for them.

I am a relatively speaking inexperienced simulator instructor so I am sure there are people out there who have seen many more of these mistakes, mistakes that should not really happen if you know your aircraft systems well.
I also have to add that most of my instructors over the years have been very good and personally I have no complaints. Some stories here makes you wonder though.....

[flyingflea]

I'm deeply shocked. Reading all these conflicting views it seems that at least some current A320/A330 pilots wouldn't be well equipped to handle a serious FCS issue. I hope someone from CAA/FAA reads this thread and takes some action. Meanwhile lets all cross our fingers and toes next time we fly as pax or FC.

[Wirbelsturm]

When I was doing my TRI in Germany, we were 5 captains. I was the only one who knew, that 3ple hydraulic means mechanical back up.

From the FCOM1


The flight controls are electrically or mechanically controlled as follows :
Pitch axis
Elevator = Electrical

Stabilizer = Electrical for normal or alternate control. Mechanical for manual trim

control
Roll axis
Ailerons = Electrical

Spoilers = Electrical

Yaw axis
Rudder = Mechanical, however control for yaw damping, turn coordination and trim

is electrical.

Speed brakes
Speed brakes = Electrical

Note: All surfaces are hydraulically actuated.

The mechanical backups provide direct control of the hydraulic actuators on the rudder and the stabaliser in the event of loss of electrical control of the actuator. No hydraulics means you can mechanically link all you want you won't be able to move the controls.

[BlackandBrown]

FCOM DSC 27-10-20:

Mechanical control of the THS is available from the pitch trim wheel at any time, if either the green or yellow hydraulic system is functioning. Mechanical control from the pitch trim wheel has priority over electrical control.

FCOM 27-20-20:

Mechanical backup enables the pilot to control the aircraft during a temporary complete loss of electrical power. He does this in pitch by manually applying trim to the THS. The PFDs display “MAN PITCH TRIM ONLY” in red.

FCOM 27-10-10:

Flight control surfaces are all : ‐ Electrically-controlled, and ‐ Hydraulically-activated. The stabilizer and rudder can also be mechanically-controlled.

But still ALWAYS hydraulically activated.

Thrust is the only method.

[CaptainProp]

Soon we should have everbody convinced that the FCOM/QRH is not wrong, what we are saying is no windup, and then we can move on to next system. Perhaps we should apply for TRTO approval for on-line airbus tech courses?! :E:ok:

[flydive1]

He/she would know what was NOT an option anymore. Is it all of a sudden acceptable to have pilots NOT knowing the systems of the aircraft they fly? What else does he/she not know? What else are these "instructors" telling crew they can or can't do with this aircraft?

Yes, he/she would know that is not an option, but would not change anything to the outcome.

1. loss of 3 hyd., knows he is screwed, gives up and dies.

2. loss of 3 hyd., doesn't know he's screwed, tries to do something, finds out he can't, gives up and dies.

No, it is not acceptable not knowing the systems(is not sudden, is quite a while that training moved from know all to know what is needed.) but him not knowing the above does not mean he has other holes in his knowledge, as knowing the above does not mean one might not lack somewhere else.

I like to believe I know everything about my aircraft, but I know I do not and I keep learning.

[autoflight]

Mechanical Back-up is a simple concept for a fully trained A320 crew. Those who say there is mechanical back-up in the event of total hydraulic failure might be trainees trying to understand their hydraulic studies.

Might as well get it wrong on pprune rather than in sim check.

[point76]

Captain Prop is correct if you check the Airbus FCOM.
If you lose all electical control of the flight control system then the THS and rudder still have mechanical control .But lose all 3 hydraulic systems and all actuation of every flight control surface is lost.Only engine control would be available to control pitch and yawing but that's assuming they still have electrical control available as the thrust levers have no mechanical connection to the engines.

[point76]

Also further to above.When I did an A320 rating back in the early days of it's introduction the 'mechanical backup' landing was part of the training mainly I think, because 'manual reversion' was always part of any Boeing rating ( eg.737/727 ) at the time so this was meant to be the Airbus equivalent of that.
If you were set up on a stable approach on a very long straight in approach with no significant cross wind it was possible to get it on the runway. Introduce any turbulence or a cross wind more than about 5 Knots and it became virtually mission impossible!

[Machinbird]

1. loss of 3 hyd., knows he is screwed, gives up and dies.

2. loss of 3 hyd., doesn't know he's screwed, tries to do something, finds out he can't, gives up and dies.
OK, Here are some aviation philosophy thoughts from a guy who has no Airbus or Boeing time. (The data plates read: North American-3 types, Grumman-2 types, Douglas-2 types, McDonnell-1 type, and a few others.) The thoughts will also apply to the Boeings



1. If you are still flying-there is still hope.

2. Even if you have no hydraulics, as long as you have symmetric engines on your aircraft, you have some control, but you are going to have to be smooth with the throttles and a bit analytical.
Remember what Captain Alfred C. Haynes and Captain Dennis E. Fitch were able to do with United Airlines Flight 232 after their triple hydraulic failure.

3. If you have time, you may have options. You can transfer fuel within certain limits to better balance the aircraft. If you are hauling SLF around in back, you can influence your c.g. by proper guidance of this potential asset.

4. With enough time, you might be able to use the crash axe to go through the aft bulkhead and directly influence the THS trim actuator (but that would have to be studied beforehand to have a real chance at success.)

5. You may have some small influence on the rudder although your abilities are miniscule compared to what the hydraulics can do. (Most rudders are still mechanically controlled. Depending on the design of the hydraulic system, you may be able to move the rudder a bit without hydraulics.)

6. I have posted some ideas that are bound to be controversial. Evaluate, and use at your own risk

7. Success can come to those who refuse to give up and continue working on their problems. Be mentally tough. Be prepared for the unthinkable.

:}

[flydive1]

Thank you for your sermon Machbird.(I also have no Boeing or Airbus time)

I'm not the one saying you are screwed if you loose the hydraulics.
Plenty of people above flying the aircraft said so, that you can kiss your ass good bye.

My comment was that if that is the situation, then knowing that you have no manual back-up or not won't change much, and to the comments that you do not know that you should not be flying and you probably do not know much about the aircraft.

I believe all, or at least most, pilot will try all to save themselves, the aircraft and in the process the passengers.

[BlackandBrown]

An additional method on the A320 is to use the electric rudder trim to control laterally - it requires no hydraulics.

[ironbutt57]

"An additional method on the A320 is to use the electric rudder trim to control laterally - it requires no hydraulics."


Think you had better have a closer look at the schematics regarding Yaw control...its electric motor 1 or 2, through an artificial feel device, then through the hydraulic jacks to the surface...

[BlackandBrown]

No you're incorrect, I tested it today, on the ground, with no hydraulic power and it works, for definite. It's electric. The schematic doesn't actually show it operating through the hydraulics. If in doubt try it before you next start engines.

[ironbutt57]

The digital position indicator in the flight deck pedestal changes, did the control surface move? was there residual yellow pressure from cargo door closing??...

[BlackandBrown]

No, no residual pressure. Why would the digital indicator move but not the surface? I admit that all I saw move was the trim on the FLT CTL page.

[ironbutt57]

Im in the sim next few nights, ill see if that replicates it...

[BlackandBrown]

If you could report back that'd be extremely helpful. Good luck in the sim.

[ironbutt57]

I'm dishing it out, so for me it's all good:ok:

[CaptainProp]

"An additional method on the A320 is to use the electric rudder trim to control laterally - it requires no hydraulics."

Please provide me with the FCOM reference where I can confirm this.

Here we go again....

All from the FCOM:

Flight control surfaces are all:
‐ Electrically-controlled, and
‐ Hydraulically-activated

The stabilizer and rudder can also be mechanically-controlled
Not mechanically/electronically activated. (my comment)

Again:

Note: All surfaces are hydraulically actuated.

Check ANY schematics of the flight controls / rudder and you will see that there is NO electrical motor or direct mechanical way of moving the rudder without hydraulic pressure.

The rudder trim simply sends a signal to the FACs (nr 1 for normal ops and nr 2 as backup) and the signals are then sent to the HYDRAULIC JACKS.

[ironbutt57]

Sans hyd pressure, primary surface does not move, the pedestal indicator will indicate a command, but the surface cannot move, as previously stated!

[TURIN]

I have the A330 Vacbi CD running on my PC now.

Assuming the 320 is similar. I know it isn't as there are no FCPCs or FCSCs but you get the gist, substitute ELACs/SECs/FACs as appropriate.

The ELECTRICAL Rudder trim actuators drive the HYDRAULIC servo controls through the feel unit and differential mechanism.

The servo units are operated by spring rods.

Position feedback to the FCPCs (and the FCSCs) is from Transducer Units that give position information of the rudder pedals.

From the schematic, rudder trim will move the pedals too so I can only assume that the trim position indication is coming from that and not from the Transducer Units on the rudder itself. They are for the rudder indication on the flt controls display, I think.

It is not clear (from my rudementary study at this time of night while watching Ellen Ripley kick the arse of another Alien) whether or not there is sufficient movement and robustness in the servo controls input rods to actually deflect the rudder in the event of a triple hydraulic failure. I suspect not or I'm sure Monseur (sp) Airbus would have labled it in big red letters.

No Hydraulics = No Flight controls. Sorry. :\

[OK465]

To turn left, apply port engine power.
To turn right, apply starboard engine power.

Why is it hard for many "pilots" on here to understand this basic concept?

Beats me.....

[ironbutt57]

Right lads, you with the Microsoft flight sims, **** off smartly.

If you want to contribute here, go out there, get yer licenses, get a job, and slug it out with the rest of us on a day-to-day basis, in shiite weather, broken airplanes, and low pay

Until that time, yer just another John Travolta.

Gayly we fly, trala feckin la...

No microsoft flight sim here my friend, TRI 4000+ PIC...validating my discussion with a previous poster to try and ascertain his findings....no hydraulics, no movement, trim indicator in cockpit indicates command, as does the cyan trim indication on the fly control page, however the rudder does not move....cheers!!!

[porch monkey]

Beats me too. Left power up to turn left? Now I know what I was doing wrong.....

[Locked door]

Must be what I was doing wrong too. Maybe M H B is doing 270 degree turns......

[Wirbelsturm]

It's quite simple, look at the rudder! No 'trim' tab visible? The the only way of trimming is through the primary flight actuators. You can't 'fly' the rudder if it doesn't have a trim tab.

Trim tabs are aerodynamically 'dirty' thus the primary flight controls are used instead.

You will still see a 'trim' demand signal through the PFC's as the system is designed to show you what the computer is demanding.

Unfortunately as there is no Hydraulic pressure at the primary actuator, the surface won't move/trim.

Back to differential thrust. :}

http://www.iloveplanes.com/wp-content/uploads/2011/08/tail-tuesday.jpg

(ATPL A+H, 10,000+, No MSFS my computers too slow!)

[patm92]

Right lads, you with the Microsoft flight sims, **** off smartly.

If you want to contribute here, go out there, get yer licenses, get a job, and slug it out with the rest of us on a day-to-day basis, in shiite weather, broken airplanes, and low pay

Until that time, yer just another John Travolta.

Gayly we fly, trala feckin la...

No microsoft flight sim here my friend, TRI 4000+ PIC...validating my discussion with a previous poster to try and ascertain his findings....no hydraulics, no movement, trim indicator in cockpit indicates command, as does the cyan trim indication on the fly control page, however the rudder does not move....cheers!!!

It needed to be said, well done ironbutt57 :D :D

[compressor stall]

On A319. Assume A320 is same in this area, although there are some odd little variations.

The rudder trim control is electrically signalled. An electric actuator installed in the tail area drives a trim screwjack via a rotary shaft and universal joints. The actuator is manually controlled via the FACs (Ref. ATA 22) from the control panel located on the center pedestal, at a constant speed.

[Wirbelsturm]

Once again, FCOM 1-27-10:

Trim is electrically demanded but Hydraulically actuated.


Yaw axis



Rudder = Mechanical, however control for yaw damping, turn coordination and trim

is electrical.





in addition the following:

RUDDER TRIM
The two electric motors that position the artificial feel unit also trim the rudder. In normal
operation, motor N 1, controlled by FAC1, drives the trim, and FAC2 with motor N 2 remains
synchronized as back-up.
In manual flight, the pilot can apply rudder trim with the rotary RUD TRIM switch on the
pedestal.
– Maximum deflection is ± 25.
– Rudder trim speed is one degree per second.
– In addition to limitation by TLU, if rudder trim is applied, maximum rudder deflection may
be reduced in the opposite direction.
The pilot can use a button on the RUD TRIM panel to reset the rudder trim to zero.
Note: With the autopilot engaged, the FMGC computes the rudder trim orders. The rudder
trim rotary switch and the rudder trim reset pushbutton are not active.

The electrical actuators effectively 'reposition' the cetre point of the Hydraulic actuator thus providing trim. This can be seen by the line ' In addition to limitation by TLU, if rudder trim is applied, maximum rudder deflection may be reduced in the opposite direction.' which demonstrates how the rudder trim is achieved by offsetting the neutral position.

Upshot? Rudder trim is not available in a total hydraulic loss. Back to differential thrust I'm afraid.

[ironbutt57]

ok folks...ALL primary flight control surfaces on ANY 318.319,320,321,330,340......are hydraulically actuated....no hydraulics...no move....some MAY be electrically or mechanically controlled, but all require hydraulic pressure to move......simple

[Wirbelsturm]

Wot he above said!

Electically controlled, hydraulically actuated.

Anyway, according to airbus Politicians will be upfront and honest before a triple hydraulic failure occurs. So we're all safe! :E

[CaptainProp]

OK, so do we agree now (finally!!) or someone else with other ideas on theories? :E

[LandASAP]

No, no residual pressure. Why would the digital indicator move but not the surface? I admit that all I saw move was the trim on the FLT CTL page.

An additional method on the A320 is to use the electric rudder trim to control laterally - it requires no hydraulics.

Come on Guys, you need to know how your Flight Controls are working?!?! That's basic knowledge for every Pilot?!

Rudder is hydraulical actuated. There is now mechanical or electrical back-up for that Hydraulic-Actuators!!!

[BlackandBrown]

Thanks to Wirbelstrum and ironbutt57 for your helpful, unpatronising inputs. As for the likes of LandASAP, your response is why you are no doubt not a trainer. Learning/ making mistakes with the oversight of more experienced pilots is how I've instilled some of my firmest knowledge.

[ironbutt57]

After a life on Boeings, one wise Airbus person gave me words to live by..."when it's all working it's fantastic, when it goes wrong it REALLY goes wrong".....how very very true...

[KBPsen]

Why would the digital indicator move but not the surface?The indicator shows the position of the Rudder Trim Actuator. A total of 4 position sensors (RVDTs) sends the angular displacement of the rudder trim actuator output shaft to the FACs and then on to the trim display as degrees of rudder trim.

[Max Angle]

Worth remembering that the same applies to all Boeing models after the 737 which was the last design to have true "manual reversion" in the elevator and aileron controls. It could be flown and landed, with effort and planning, with no hydraulic power.

I have had a go at thrust only control in a 320 sim and it can be flown around the sky without too much trouble after a bit of practice but I found a "walk away from" landing was impossible to achieve if starting clean with the gear up. If you failed everything with gear down and some flap out it was possible to arrive on the ground in about the right place, not pretty but survivable. My respect for the few who have pulled it off in real life is immense.

[galaxy flyer]

LandASAP

There was a time pilots got "hands on" explanation of the mechanical parts of planes, how they functioned, what the inputs were and so on. Now, it's all, "if you can't fix or touch it, you don't need to know it" which is quite incomplete.

[ironbutt57]

The 787 now has "electrical reversion...one spoiler pair and the stab are electrically controlled AND actuated...