What is damping mode in A320?
I'm going for my type rating soon and I'm working through as many CBTs as I can and I would appreciate if anybody could help me out on this concept.
I've tried researching this everywhere but I can't seem to find a reasonable answer that would satisfy my curiosity So in the Flight Controls CBT, it's mentioned that ELAC 1 and ELAC 2 help control the elevators, THS and ailerons. ELAC 1 is in active mode for ailerons and damping mode for elevators. Similarly ELAC 2 is in active mode for elevators and damping mode for ailerons. What is this damping mode? All I get is that in the active mode the jack is electronically controlled and in damping mode it follows surface movements? Am I correct in assuming that active mode is the normal law and damping mode is either alternate or direct law, wherein side stick movement is directly proportional to surface movements? Thanks in advance! Sincerely, A thoroughly confused soul |
That’s not my understanding of it. Active and damping modes have nothing to do with flight control laws.
The CBT you have looked at is a little misleading, because active and damping mode refers to the hydraulic jacks in the flight control surface itself. So, in normal flight, ELAC 2 controls the elevators through the green and yellow hydraulic systems. This means the hydraulic jacks in the elevator that are doing the actual pushing and pulling are the green and yellow ones, these are the “active” ones. The damped Jacks are controlled by the blue hydraulic system and act as a damping force or drag on the active jacks. This serves to smooth out the control surface movement much like the dampers in your car. Only if ELAC 2 fails, would the blue jacks take over, because ELAC 1 is now controlling the elevators, and the green and yellow jacks becoming the damping force. A single ELAC failure would not result in a flight control law downgrade, and you would remain in normal law (had to look that up!). That’s my understanding of the system, and am happy to be corrected if I'm wrong. My advice to you would be to avoid CBTs at this stage and get a copy of the FCOMS instead. |
Agreed. If the overload of study is actually required by the TR school or national CAA, it's a great pity.
There's a lot of stuff that actually will need learning and filling the brain storage with minutiae like this will definitely cause more harm than good. Not the OP's fault, at this stage he absolutely cannot recognize the importance of different bits of information. With much good success, get a copy of the latest (new SOP) edition FCTM and print it. No, the iPad won't do because that's where the FCOM is and QRH ;-). Pre-studying that will not do harm and will lead you to the important parts of the FCOM. Another nice book to get oriented is here https://www.smartcockpit.com/aircraf...or_Pilots.html, a bit aged but the scope is perfect before the course actually starts. Enjoy! |
The number of the ELAC or SEC below the control surface; the hydraulic jack colour and the arrow shows the chain of control.
So for example: normally the left aileron is controlled by ELAC 1 using only the Blue Hyd jack. If ELAC 1 or Blue Hyd fails, control passes to ELAC 2 using only the Green Hyd jack. The left elevator is normally controlled by ELAC 2 using the Green Hyd jack. If ELAC 2 or Green Hyd fails, control passes to ELAC 1 using the Blue Hyd jack. Or, if ELAC 1 and 2 have failed, control passes to SEC 2 using the Green Hyd jack, etc. On each surface, the jack not in use performs a damping function - its hydraulic fluid is put into a closed loop which damps the control surface; preventing flutter etc. https://cimg6.ibsrv.net/gimg/pprune....878309987.jpeg |
Originally Posted by Jonty
(Post 11229363)
The damped Jacks are controlled by the blue hydraulic system and act as a damping force or drag on the active jacks. This serves to smooth out the control surface movement much like the dampers in your car.
My advice to you would be to avoid CBTs at this stage and get a copy of the FCOMS instead. With respect to the FCOMs, I have the latest one with me, but I found the FCOMs to be a bit dense at the moment. I thought once I start my type rating, I'll finally start reading up on it. Wrong approach? |
Originally Posted by FlightDetent
(Post 11229380)
With much good success, get a copy of the latest (new SOP) edition FCTM and print it.
I'm also just figuring out the ins and outs of the MCDU on the x plane sim just to get a general idea. You think that's a good idea or should I just wait for the type rating to start?
Originally Posted by FlightDetent
(Post 11229380)
Another nice book to get oriented is here, a bit aged but the scope is perfect before the course actually starts. Enjoy!
|
Originally Posted by Uplinker
(Post 11229439)
The number of the ELAC or SEC below the control surface; the hydraulic jack colour and the arrow shows the chain of control.
So my understanding is that for example: normally the left aileron is controlled by ELAC 1 using only the Blue Hyd jack. If ELAC 1 or Blue Hyd fails, control passes to ELAC 2 using only the Green Hyd jack. The left elevator is normally controlled by ELAC 2 using the Green Hyd jack. If ELAC 2 or Green Hyd fails, control passes to ELAC 1 using the Blue Hyd jack. Or, if ELAC 1 and 2 have failed, control passes to SEC 2 using the Green Hyd jack, etc. On each surface, the jack not in use performs a damping function - its hydraulic fluid is put into a closed loop which damps the control surface; preventing flutter etc. If ELAC 1 (and by extension the blue hydraulics) responsible for the left aileron fails, then ELAC 2 would end up controlling the right aileron using the blue hydraulic jack. Correct? If that's the case then how is this possible? Since the blue hydraulics already failed when ELAC 1 failed. Or do the blue hydraulics for both the left and right aileron act independently of each other? |
I would read and understand the section on flight controls and auto-thrust. It is really important to understand how they work and the logic involved. Airbus FBW flies just like a conventional jet, you just have to understand how the design engineers have made your life easier by the way you control it.
Also the speed tape; Green Dot, VLS, Alpha Prot, Alpha Max etc - very important to understand these and how the aircraft and auto-thrust will interact with them. Understand how Ground speed mini operates on approach. Instead of referencing IAS; Ground speed mini ADDs thrust if the head wind increases and REDUCES thrust if the headwind reduces - within certain limits. So it locks the ground speed on approach, not the air speed, and is why the engines can thrust up and down a lot on a turbulent approach. This is opposite to conventional systems but it keeps the aircraft energy constant with changing head winds. Nobody I have ever been taught by could teach the side-stick. Hold it properly like a pistol. If you need to make a correction move the stick until the aircraft attitude is where you want it, then return the stick to neutral. Airbus FBW will hold that attitude you have set - within reason and certain limits. (The FBW has surface and aircraft feedbacks to enable it to adjust the flight controls in the background to hold your selected attitude). Make small side-stick corrections and always return to neutral between each input. There is a large arm rest on the outboard side of your seat. Adjust this this to rest your forearm along when you hold the side-stick. It will make your manual control much smoother. The Airbus FBW auto-thrust is brilliant. It is a very logical system, and works very well. The auto-thrust will move the thrust between IDLE and CLB or MCT, depending which detent the thrust levers are in. If you click the levers out of a detent, the thrust will rapidly change to match whichever angle the levers are at, and then you have manual thrust - push forwards for more thrust, pull back for less. At any time, from any position or detent; pushing forwards will give you more thrust, just like any jet. The levers don't move by themselves so it simply means that you look at the engine N1 or EPR gauges to see any thrust changes instead of looking at the thrust levers themselves. You are looking at the instruments anyway, so you can see exactly what is happening. On the FCP; if you pull SPD, HDG, ALT, V/S out towards you, you are telling the Airbus "do what I select". If you push them in you are telling the Airbus "you control it according to what I have programmed in the FMGS", e.g. Managed Nav. A reasonable understanding of how to use the MCDU to enter basic flight data, waypoints and and routes will be a great help in setting up the SIM. Airbus FBW is a fantastic machine. Enjoy ! |
Originally Posted by mahendru1992
(Post 11229464)
Thanks for the reply! Just one question
If ELAC 1 (and by extension the blue hydraulics) responsible for the left aileron fails, then ELAC 2 would end up controlling the right aileron using the blue hydraulic jack. Correct? If that's the case then how is this possible? Since the blue hydraulics already failed when ELAC 1 failed. Or do the blue hydraulics for both the left and right aileron act independently of each other? - In the first case (ELAC1 failed), ELAC2 will control left aileron using Green HS and right ailerone using Blue HS. - In the second case (ELAC1 and Blue HS failed), ELAC2 will control left ailerone using Green HS and right ailerone will switch to damping mode (that means that ailerone will be slowly moved by aerodynamic forces and jack will follows surface movement) - in the 3rd case (Blue HS failed), left ailerone will switch to damping mode and ELAC1 will control right ailerone using Green HS. |
Originally Posted by Uplinker
(Post 11229623)
No, look again at the diag I posted and the coloured circles I drew on: ELAC 1 controls only the Blue jack in the left aileron. If ELAC 1 or Blue hydraulics fail, control will be passed to ELAC 2, which only controls the Green jack in the left aileron - that is what the diagram is showing you, but it is a bit subtle.
|
Originally Posted by mahendru1992
(Post 11229464)
Thanks for the reply! Just one question
If ELAC 1 (and by extension the blue hydraulics) responsible for the left aileron fails, then ELAC 2 would end up controlling the right aileron using the blue hydraulic jack. Correct? If that's the case then how is this possible? Since the blue hydraulics already failed when ELAC 1 failed. Or do the blue hydraulics for both the left and right aileron act independently of each other? The right aileron is normally controlled by ELAC 1 using only the Green jack, so if Blue Hyd and ELAC 1 failed, you would be left with left aileron only, controlled by ELAC 2 using the Green jack. (You would also have most of your roll spoilers) Yes, all the controls work independently, to give redundancy. Certain hydraulic and FBW failure combinations will leave you with a single aileron or elevator. |
To my previous question.
I always thought that only one ELAC can be in control of ailerones. So you cannot use ELAC1 for your right ailerone and ELAC2 for your left ailerone at the same time. Am I correct? Or not? |
The arrows on the hydraulic architecture diagram tell you which FBW computer normally controls which flight surface and which computer takes over from it. All the ELACs, SEC and FACs are used all the time - that is how they monitor each other and take over or assist when required.
|
Originally Posted by Uplinker
(Post 11229639)
The arrows on the hydraulic architecture diagram tell you which FBW computer normally controls which flight surface and which computer takes over from it. All the ELACs, SEC and FACs are used all the time - that is how they monitor each other and take over or assist when required.
Thanks anyway! Always nice to refresh knowledge. |
Yes, let us know :ok: I can't think how to confirm one way or the other?
|
Originally Posted by Samten
(Post 11229635)
To my previous question.
I always thought that only one ELAC can be in control of ailerones. So you cannot use ELAC1 for your right ailerone and ELAC2 for your left ailerone at the same time. Am I correct? Or not? If you lose Blue Hyds, then the only surface you lose is spoiler 3. Therefore the Left Aileron must be controlled by ELAC 2 with Green Hyds and Right Aileron must be controlled by ELAC 1 with Green Hyds. |
No, actually, I think I was partly wrong. I have just re-read DSC-27-10-20 "Roll control" which states, (from Airbus FCOM):
ELECTRIC CONTROL
Also, while I am in the FCOM: AILERONS Each aileron has two electrically controlled hydraulic servojacks. One of these servojacks per aileron operates at a time. Each servojack has two control modes : Active :Jack position is controlled electrically Damping :Jack follows surface movement. . |
And here is the full Hyd architecture diag to make our cross referencing easier ! From Airbus A320 FCOM :
https://cimg5.ibsrv.net/gimg/pprune....2ffdcb5da8.png |
I asked my friend to check it in the sim (haven't seen it by my eyes, so I'm not 100% sure).
Switched off Blue HS. Both ailerons operable (from Green HS). So my previous post was wrong. Thanks guys! Now the interesting part: Next ELAC2 was switched off (with Blue HS already offline). One aileron stopped operation! Bottom line: In case of HS failure BOTH ELACs can operate simultaneously - each moving one aileron. But, in fact, each ELAC is hard-wired to only one jack per aileron. So in case of Blue HS failure, ELAC1 cannot simply switch to Green jack on the left aileron and needs help from ELAC2. |
Originally Posted by Samten
(Post 11229782)
I asked my friend to check it in the sim (haven't seen it by my eyes, so I'm not 100% sure).
Switched off Blue HS. Both ailerons operable (from Green HS). So my previous post was wrong. Thanks guys! Now the interesting part: Next ELAC2 was switched off (with Blue HS already offline). One aileron stopped operation! Bottom line: In case of HS failure BOTH ELACs can operate simultaneously - each moving one aileron. But, in fact, each ELAC is hard-wired to only one jack per aileron. So in case of Blue HS failure, ELAC1 cannot simply switch to Green jack on the left aileron and needs help from ELAC2. |
Originally Posted by mahendru1992
(Post 11229462)
I'm also just figuring out the ins and outs of the MCDU on the x plane sim just to get a general idea. You think that's a good idea or should I just wait for the type rating to start?
Mileage may vary. FCTM with the new workflows - don't have that one myself. :sad: |
Re the MCDU;
Don't worry too much - the basics of flying, instrument scan, and understanding and controlling the aircraft need to be acquired first. But as I said earlier, if you have spare capacity it would be helpful if you know how to input a basic set-up e.g.: City pair. SID. STAR. Runways and approach type. Cruise Alt. Take off mass and V speeds. Tower wind and outside air temperature. How select and programme a holding pattern. All these data will be given to you initially; you just need to know how and where to put them in via the MCDU - it is not difficult, but it helps to know. If you can do these basic inputs, it will save time in the SIM setting up. It will also let the TRE see that you are reasonably competent and don't need baby sitting over every detail, which will make his/her life easier. But again, learning to control and fly the aircraft is the priority. |
Originally Posted by Uplinker
(Post 11230074)
Re the MCDU;
Don't worry too much - the basics of flying, instrument scan, and understanding and controlling the aircraft need to be acquired first. But as I said earlier, if you have spare capacity it would be helpful if you know how to input a basic set-up e.g.: City pair. SID. STAR. Runways and approach type. Cruise Alt. Take off mass and V speeds. Tower wind and outside air temperature. How select and programme a holding pattern. All these data will be given to you initially; you just need to know how and where to put them in via the MCDU - it is not difficult, but it helps to know. If you can do these basic inputs, it will save time in the SIM setting up. It will also let the TRE see that you are reasonably competent and don't need baby sitting over every detail, which will make his/her life easier. But again, learning to control and fly the aircraft is the priority. Basically, I had a lot of free time because of which I decided to just get a 'more than basic' understanding of the A320. In my mind, I just wanted to be slightly ahead of the learning curve for when I leave for my training in about 10 days. I've heard type rating on the A320 is like soaking in information from a fire hose Regarding the instrument scan pattern, do you have any good documentation or videos I can refer to? I can and will google all this, but if I get a verified source from pilots like yourself, I'll know that whatever I'm reading and studying is all bona-fide. Then I can practice a bit on the SIM. Not the flying part of course, since I don't think a home sim could exactly replicate the physics of flying an actual aircraft, just the basic procedures and scan pattern, as you mentioned. I'm also going through the checklist both as PF and PM. Is it a bad idea? Should I stop? I haven't been flying since the past 2 years courtesy covid, and I'm pretty sure I'm a bit rusty with IFR haha. I have this opportunity finally. I don't want to mess it up and want to be as prepared as I can. If you have any other advice for me, please let me know. Thanks! |
No time for a comprehensive reply at the moment. I don't know of any videos and am not a trainer, but as far as the instrument scan goes, the basic T scan still works on the PFD, but also include the ENG instruments on the EWD (top middle screen).
Even when on automatics, scan regularly - just a glance will normally do. If you see anything not quite right, make sure the automatics, including the auto-thrust, are compensating. If not, step in. Don't get suckered into the flight director. Look through it at the actual attitude of your aircraft. Always read, confirm and understand your FMA. I would say no problem with reading PF and PM checklists if you have time, but I wouldn't try to learn them all as some do. You only need to learn the cockpit scans, flows and memory drill actions for PF and PM. Master the side-stick and adjust the arm rest to support your forearm along it's length. Hold the side-stick fully, in a pistol grip. When the attitude is what you want, centre the side-stick then leave it centred until another correction is needed, and re-centre after that one and so-on. The Airbus FBW will hold your attitude within reason, so you don't need to continuously fiddle with it. Understand how to operate the thrust levers, what all the detent positions do, and what the auto-thrust does, and what will happen if you click out of a detent. Understand the speed tape, what all the bugs and indications mean and how the auto-thrust will react. Ditto Ground speed mini. Good luck :ok: |
Did we just suggest studying GS mini to someone who has not started the course yet?
Hope not, otherwise the next would be to go read about the different versions of (degraded) alternate law, why set MDH on an older QFE option airplane when flying QNH approach, different flap angles between 232 and 214..... Sorry, exactly the wrong topic. One that will take days to understand and master + retain the knowledge as opposed to 10 minutes with a good instructor on APT. Speaking of instructors - that is the reason behind having the FCTM. To cover and fill the holes left by imperfect human tutors. Some are beartraps. |
You might be right, perhaps not needed for the Sim, but I have witnessed type-rated line pilots who clearly had no clue how G/Smini works or what it does, and they almost panic when the speed bug jumps 20kts up and down on approach.
They seem to think the auto-thrust is going wrong and sometimes take it out and fly the old fashioned way - constant IAS - not realising that that is more dangerous, without a fixed IAS increase above Vapp. Sim rarely has turbulence or wind gradients on approach :) . |
Agreed, it is part of the TR knowledge.
Explained once during the course and then stored in the very far corner of the server room, only to be later revived by LTI during IOE. It was an item on the 'mandatory training and demonstration topics' on the linetrainings I've seen. You want to have the FCTM from early on to see which topics the instructors miss altogether. |
Originally Posted by Uplinker
(Post 11231416)
You might be right, perhaps not needed for the Sim, but I have witnessed type-rated line pilots who clearly had no clue how G/Smini works or what it does, and they almost panic when the speed bug jumps 20kts up and down on approach.
They seem to think the auto-thrust is going wrong and sometimes take it out and fly the old fashioned way - constant IAS - not realising that that is more dangerous, without a fixed IAS increase above Vapp. Sim rarely has turbulence or wind gradients on approach :) . |
Exactly.
I am not a trainer but I once had to explain - with diagrams - to a very experienced Captain, (ex Boeing type rated), what G/Smini was actually doing in varying headwinds. He wanted to pull selected speed to stop the IAS bug moving and the auto-thrust reacting. I think they get nervous if thrust is added at very short finals. Anyway, sorry for the thread drift. |
Damping mode simply means that the elevator is not hydraulically controlled. You must remember that all surfaces are electrically controlled and hydraulically actuated. So if the hydraulics fail, then with what will you control the elevator?
|
As stated in post #4 :) In more detail; the hydraulic flow and return pipes to the jack are connected together with a valve and away from the supply and return lines, forming a closed-circuit passageway through which fluid can flow when the piston is moved, (by the other jack acting on the control surface). The slight resistance to the flow of this fluid through the closed-circuit passageway when the piston moves, is what provides the damping effect.
I cannot find the diagram of this in the FCOM now - sure it used to be there? |
Damping mode means the nonactive jack passively follows the control movements. In case of failure of the active jack it takes over from there.
|
All times are GMT. The time now is 18:25. |
Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.