Air Canada A320 loss of control in flight: 14/4/09

[MFALK]

Any more details on the following report from Avherald?


Incident: Air Canada A320 near Montreal on Apr 14th 2009, loss of control in flight
By Simon Hradecky, created Wednesday, Apr 15th 2009 21:41Z, last updated Wednesday, Apr 15th 2009 21:41Z

An Air Canada Airbus A320-200, registration C-FTJQ performing flight AC-926 from Montreal Trudeau,QC (Canada) to Fort Lauderdale,FL (USA), was enroute at FL360 about 170nm south of Montreal about 30 minutes into the flight, when the crew requested to return to Montreal and reported problems with the flight controls. The airplane was on final approach to runway 06L about one nautical mile before touchdown, when the crew declared emergency and requested emergency services to standby. The airplane continued for a safe touch down and stopped on the runway for about 10 minutes. The crew reported, that they had experienced "severe mechanical turbulence" and had lost control of the airplane momentarily.

A replacement Airbus A320-200 registration C-FFWI resumed the flight and reached Fort Lauderdale with a delay of 3:45 hours.

FlightAware > Live Flight Tracker > Air Canada #926 > 14-Apr-2009 > CYUL-KFLL (http://flightaware.com/live/flight/ACA926/history/20090414/2058Z/CYUL/KFLL)

[captplaystation]

Shades of Qantus ? :=
That old luddite in me is coming out the cupboard again. :hmm:

[captainspeaking]

captplaystation

You wouldn't be suggesting - in the most subtle way - that FBW is, perhaps, not entirely, 100% completely and without question, foolproof, would you?

[captplaystation]

I think unfortunately, that has been proven several times, be it the "system" or the poor humans inability to sucessfully interface with it, often with loss of life, or in the Qantas case perhaps merely a loss of personal hygeine :rolleyes: :yuk:
IMHO it is a can of worms and everytime something else happens always we end up with the FBW defenders vs the luddites. We have done it to death so often here, purely my opinion, but no I don't trust it any more than I would a politician.

[Gretchenfrage]

And just why isn't anybody surprised, alarmed or outraged?
We all shrug our shoulders and think: "Nothing we can do about it, at least it didn't happen to me". :ouch:
Brave new world! :(

[shortfinals]

Captplaystation

Luddite about FBW, eh? That include the 777? Then the 787?

Or are we talking sidesticks versus something between your legs?

As for just shrugging, what else is there to do until we actually know something? At present we know the square root of sweet FA.

[CerealAbuser]

When you lose the FBW the Airbus still gives you mechanical flight...does it not?...
That's all I remember...Air Transat A310 maybe..cant remember

[ZEEBEE]

As for just shrugging, what else is there to do until we actually know something? At present we know the square root of sweet FA.


Actually, I think it's (2/3 * Sqrt(SFA))

[tubby linton]

I remember being shown a quite innocuous series of hydraulic and fbw failures in the A320 sim that collectively induced a rapid increase in pitch that had to be countered by smart action on the trim wheel and simultaneous disconnection of the auto thrust.It was not pleasant even when you knew it was coming.Airbus fbw is definetley not for the complacent.

[hetfield]

When you lose the FBW the Airbus still gives you mechanical flight...does it not?...

The design is to keep it flying until one/some/all flt ctl computers are back. It's not designed to fly an approach.

[Re-Heat]

Depends on model - stab trim control is common as a backup, but not much use for approach.

[Flare-Idle]

...once again wait to be extracted/downloaded from the very magic DFDR of said aircraft and subsequently being put in perspective for said incident by the real professionals of the Canadian AAIB and Air Canada...

...as an Airbus A320 series pilot myself, desperately waiting for the initial outcome of the probe with valuable hints for our daily ops, however I already fear the deja vue of loads of rubbish statements of all those desperate "hobby" wannabee AAIB posters in this thread...

[PJ2]

hetfield;
The design is to keep it flying until one/some/all flt ctl computers are back. It's not designed to fly an approach.
That applies to the 330/340 but less so to the 320 series - the aircraft can (and has, I have been told by someone who did it, in test flights) be flown to the landing on the stab trim alone. I've done it in the sim and while it's not pretty, it isn't an automatic accident either.

That said, I see the anti-AB, anti-fbw troups are out in force, jawing without having the slightest idea as to what happened, (because they don't yet know) and why, (because they haven't flown the Airbus and know nothing about it), but ready to tell us, without knowledge and understanding, that any Airbus incident is "proof that the Airbus, and fbw are dangerous", which is nonsense.

The issues associated with the 320 series are knowledge and training based, not design based.

The Boeing question has not been answered, nor have any obvious-though-unasked questions regarding military aircraft and fbw. One would be much farther ahead in learning about and discussing the habits of the DC10 and MD11. "The DC10 Case", (Suny press (http://www.sunypress.edu/details.asp?id=52521)) is well worth reading. No such books are available/written on the Airbus and fbw because the accident rate is not anomalous when compared with similar types/routes etc.

CerealAbuser;
When you lose the FBW the Airbus still gives you mechanical flight...does it not?...
In a word, yes. Providing the aircraft has hydraulics, the rudder and horizontal stab are available. There are no fatal accidents caused through loss of control through failure of fbw. Such failure is far more rare than loss of control through complete loss of hydraulics, which has resulted in fatal accidents.

[act700]

hetfield;
Quote:
The design is to keep it flying until one/some/all flt ctl computers are back. It's not designed to fly an approach.



What if it takes more time (for the flt ctl comps to come back) than you have fuel?!
Sounds funny, that's all. Not really pro or con as far as the bus is concerned.

[hetfield]

@act700

To make it clear. My post wasn't MY opinion!

It's the way I have been trained on A320 with a major Western Carrier.

regards

[tubby linton]

Having had a look at the TSB Canada website I wouldn't hold your breath waiting for a report from them on this one!
The most recent report they have on their website is of a hard landing of a balloon in August 2007!:eek::ugh::eek:
Transportation Safety Board of Canada - AVIATION REPORTS (http://www.tsb.gc.ca/eng/rapports-reports/aviation/index.asp)

[Iceman49]

Hope its not self-inflicted...one of our great men of genius, fancied himself a computer expert and thought that turning off the flight control computers momentarily would correct whatever problem they had.

[PJ2]

Iceman49;
Hope its not self-inflicted...one of our great men of genius, fancied himself a computer expert and thought that turning off the flight control computers momentarily would correct whatever problem they had.
The Airbus 320/330/340 QRHs have mandatory reset procedures for troubleshooting all computers on board which may affect the operation. These procedures have been in use for a very long time and will be trained for and should be well understood. One just doesn't launch on a troubleshooting expedition in the 320 or any computerized device with home-grown or internet-researched "solutions". If a crew doesn't go by the book, then that is a training and standards issue, not an airplane issue.

act700;
What if it takes more time (for the flt ctl comps to come back) than you have fuel?!
Well, aside from being a straw-man argument, when serious problems arise, like any professional airman would, you deal with it...obviously. That's what we do. That said, the most serious computer issue to occur thus far, (QANTAS A330), did not present this problem. Not saying it can't happen but your question is quite far into hypothetical vs possible/probable. Such a scenario is not even in any training syllabus I know of - you're simply expected to deal with it.

The A320 is quite flyable on reduced ELAC/SEC/FAC authority, as described. Just as some people still think that "stall" means the engines quit on an airplane, some believe that the 320 stops flying when the computers "quit" - its a much more sophisticated design than that and if we think about it, would have to be to have survived this long without a computer-related accident.

Cheers,
PJ2

[Dream Land]

Can't believe the mobile phone police haven't piped in yet. :}

[snowfalcon2]

The issues associated with the 320 series are knowledge and training based, not design based.
With all respect I'd say the answer may be more complex than that. Obviously the designer has to include with the design sufficient operational training materials and tools to enable training of operators and crew, and of course Airbus have done that. But what about the case, for example, when you have a 6000 hr pilot transitioning from another brand of a/c who has to de-learn old ingrained procedures - is that addressed good enough in the training? Is it even possible to retrain someone so well as to guarantee that his old habits don't surface when faced with a "situation"? Just asking...

[daikilo]

Just speculation, but would this by any chance be the first flight after a maintenance action?

[lomapaseo]

Just speculation, but would this by any chance be the first flight after a maintenance action?

Not really speculation to ask a question, without presuming the answer.

Now an example of informed speculation would be:

"It's probably the last flight before a maintenance action"

[Mad (Flt) Scientist]

Just speculation, but would this by any chance be the first flight after a maintenance action?

Seems unlikely since the Flight Tracker linked on the first post claims a 1708EDT departure time. Any significant maintenance action of the kind usually associated with flight control oddity tends to be during an overnight or longer maintenance opportunity, and thus first flight of the day, which it seems unlikely this would be for the airframe.

[PJ2]

Snowfalcon2;

Of course it's more complex than that which I state. The statement was posted against the mistaken notions, mostly from 320 critics who either dont' fly or haven't flown the Airbus, that it is not the design towards which one looks for the sources of problems but training and standards/checking, which must be reinforced by a good data analysis program that is accepted and used by the operator.
what about the case, for example, when you have a 6000 hr pilot transitioning from another brand of a/c who has to de-learn old ingrained procedures - is that addressed good enough in the training?
Well, who's training are we discussing in "the" training? Each operator is responsible for the training supplied to their pilots. Some consider it at the same level as a home study course while others do serious in-depth computer-based ground school and simulator programs consisting of at least seven (absolute minimum for a full transition) to more. I suspect the standard varies across operators - it's not a course by Airbus nor is it Airbus's course - usually it is a course designed by the operator and bought from one of many private companies who supply these kinds of courses. So you question is not answerable in the way it is asked.

Someone with only 6000hrs isn't (or shouldnt') have any problem transitioning from, say, a 737 to a 320 or right seat to left seat. Its an airplane first, then a software platform to greater or lesser degrees. Learn to fly the airplane, then learn to work the bells and whistles, (most courses do not do that, but that's a training issue, not an aircraft issue).

[airfoilmod]

Makes more sense than most. A computer generated loss of control is as common as what, a Rudder hardover in a 73? The airframe has a better record than the pilot, regardless the (similar) type. A quick review of all the threads here would bear that out.

AF

[PJ2]

airfoilmod;
A computer generated loss of control is as common as what, a Rudder hardover in a 73?
No, that is not the case.

The question assumes, and is stated "as though", computer-generated loss of control is in the same league as the 737 rudder issue. It is not. The 737 rudder hardover has a historical record, has caused a number of fatal accidents and has an established training regime designed specifically to counter the occurence, while there is only one computer-generated loss-of-control accident which was unprecedented, (ie, not indicated in any flight data or incident report before the occurence), non-fatal, and in which the aircraft landed safely.

Again, this is not to say that computer-generated issues are not possible. No one can say this. But the record is what it is. Loss of control through a computer-generated problem is statistically close to zero; the rudder hardover case is not, and it is not "rare" - in fact, the problem exists today because, while the rudder power units have been redesigned, they are not installed on the entire fleet, (someone please correct me on this if wrong - this is my recollection).

Please know that I'm not defending one over the other here, I'm simply pointing out the problem with the question's assumptions, as posed. I dont' think the question addresses the Airbus issues which have arisen in the accidents which have occurred thus far.

[airfoilmod]

PJ2

I presumed most would assume I meant merely what you took the time to explain, that the two were not at all comparable in order of occurrence, that with either type, the a/c is predictable in the way you state, statistically, whereas flight crew are not conducive to such methods.

I fear that lost in the parochial approach to type is a failing of what is mitigable, Human (Pilot) error. Exhaustively designed and built aircraft seldom surprise, and when they do, there is a trail to follow backwards to the procuring cause.

[PJ2]

whereas flight crew are not conducive to such methods.
Ah, thanks...yes.

[pool]

Loss of control through a computer-generated problem is statistically close to zero

... therefore, by your beautiful approach to statistics, any loss of control of a FBW aircraft is a pilot scr*w-up. (it's elementary, Watson ...)

Such BS comes in very handy for the manufacturors, the lobbied-up regulators and the stingy airline managers. :ugh:

[slamer.]

Luddite about FBW, eh? That include the 777? Then the 787?

Or are we talking sidesticks versus something between your legs?




B777 still has cables...!

[Iceman49]

The Airbus 320/330/340 QRHs have mandatory reset procedures for troubleshooting all computers on board which may affect the operation. These procedures have been in use for a very long time and will be trained for and should be well understood. One just doesn't launch on a troubleshooting expedition in the 320 or any computerized device with home-grown or internet-researched "solutions". If a crew doesn't go by the book, then that is a training and standards issue, not an airplane issue.


Agreed training and standards is an issue, not the aircraft, however you can have all of the training and standards you want, but if you have an idividual go off on their own... all bets are off. The only measurement tool we had before, is sim and line check rides, now with FOQA there is the ability to actually see if what is being taught and checked is truly being complied with.

An operator recently told me that they had no problems on line checks and sim checks, I said a sim is an artificial enviornment and both on the sim and line the pilot is on their best behavior during the checking event. The operator did not have FOQA or ASAP...so they really did not know what was going on with the line pilots.

[PJ2]

Iceman49;
Agreed training and standards is an issue, not the aircraft, however you can have all of the training and standards you want, but if you have an idividual go off on their own... all bets are off. The only measurement tool we had before, is sim and line check rides, now with FOQA there is the ability to actually see if what is being taught and checked is truly being complied with.

An operator recently told me that they had no problems on line checks and sim checks, I said a sim is an artificial enviornment and both on the sim and line the pilot is on their best behavior during the checking event. The operator did not have FOQA or ASAP...so they really did not know what was going on with the line pilots.
Yes, fully agree with you.

Today, an airline that is operating without a FOQA program and therefore doesn't know what it's fleet is doing on a daily basis, or an airline that has the FOQA box ticked but isn't examining the data, hasn't staffed the program with sufficient resources or doesn't engage the program, is an airline that is exposed to risk in a number of ways.

A checking program which does not include FOQA data reviews with a robust reporting system to the flight operations VP and higher, is no longer the best checking program. It is no longer good enough under SMS. It will be prone to observer biases which tend to see what flight operations wants in terms of results; ignoring or paying lip service to FOQA data permits commercial priorities to take precedence over safety under the heading of "we didnt' know", which is, of course, a variation on wilful negligence, especially if the data contained, for example, an airframe limitation exeedance (speed, 'g', engine temps, etc) but was kept flying for whatever reason. In short, while all kinds of things used to happen when the data wasn't available, it is no longer acceptable for an airline to run without such data programs.

A flight operations group which doesn't have, or if it does, doesn't look at the FOQA data, doesn't know what trends and/or incidents have occurred but which are not, for varying reasons, reported, it doesn't know what it's normal operation looks like, (how tight are the bell curves in terms of stable approach parameters - is the curve "peaky" or wide, with lots of outliers?) and, because SMS is a data-driven program and because computing power and box installations are relatively cheap as is the ability to examine the data daily, if the airline has an accident and it can be demonstrated by the prosecution that that airline either didn't have a FOQA program in place, or if it did, was in possession of safety information but didn't act upon it or, if the program was in place with a couple of token resources but flight operations routinely ignored the data even when serious incidents were seen in the data, then that airline is at legal and economic risk. FOQA programs can save an airline millions but it first has to be understood, engaged in and supported; otherwise all the predictions that those ignorant of FOQA make, actually come true as a self-fulfilling prophecy.

In short, if you're not doing FOQA, you're at risk; if you're doing FOQA and not looking at the data, or looking at the data but doing anything about it, (contrary to the FAA laws on FOQA confidentiality and keeping the FAA at arm's length), you're at risk. Add to this mix the fact that the regulator is vacating it's traditional role and de-regulating safety by handing the responsibility over to private enterprise. More than ever now, an airline needs to know how it's fleet is being flown and what trends if any, are present.

Sorry for the thread-drift.

[bnt]

According to The Aviation Herald (http://avherald.com/h?article=4181e1c9&opt=0), the crew reported "severe mechanical turbulence". Do I want to know what that means..? :ooh:

[daikilo]

for those who wish to stay on the topic, would this by any chance have been the first flight after a maintenance intervention?

[PJ2]

daikilo;

Your question wasn't responded to likely because nobody knows yet or if they do they're not publishing it.

What do you mean by "maintenance intervention"? Any action outside of the normal, planned maintenance actions before each flight or an MEL item at the gate, or fresh out of the hangar after a major check?

PJ2

[Broomstick Flier]

Mechanical turbulence generally refers to turbulence caused by the wind hitting obstacles (like mountains) and being affected (updrafts/down-drafts) by them, but I don't think this was the case at FL360.

Perhaps they meant CAT?

BF

[fc101]

Slamer:

Luddite about FBW, eh? That include the 777? Then the 787?

Or are we talking sidesticks versus something between your legs?

B777 still has cables...!And how do cables differ when they're ultimately moved by computer? Don't forget the 737NG either...but I guess you're just spoling for an AvB fight...

..does slamer refer to your landings in MSFS? (You've spelt slammer wrong as well or did you mean s-lame-r )

FC101
E145 driver

[tubby linton]

From the Avherald:
The Canadian TSB reported on Apr 20th, that the crew received a "SPOILER FAULT" message on the electronic centralized aircraft monitoring system (ECAM) and noticed, that the ground spoilers were partially removed from the display. After consultation with the airline's maintenance department the crew decided to return to Montreal. On short final the crew declared emergency due to severe vibration of the airframe. The aircraft had undergone maintenance during which the ground spoilers had been disabled and were not reactivated. The airframe vibrations came from the spoilers, that started to flutter after the landing flaps were deployed.

[GearDown&Locked]

The airframe vibrations came from the spoilers, that started to flutter after the landing flaps were deployed.

Makes all the sense.

No FBW issue here, move along :cool:

[cod liver oil]

If the ground spoilers were indeed left in maintenance mode, wouldn't the crew have noticed this during their pre-departure flight control checks?

just curious

cod

[Mad (Flt) Scientist]

Ground spoilers wouldn't usually move in response to roll control inputs or to flight spoiler selection. I'm not sure how common actually checking the ground spoilers is ...?

Ignore that, it does happen, I just hadn't noticed it

[PJ2]

Mad (Flt) Scientist, cod liver oil:

The flight control check is done very thoroughly, before every flight. The position of the controls is monitored on the Lower Ecam as the check is done.

Here's how the 320 flight control check might go - no particular airline's procedures, just an example:

Prior to performing the rudder pedal check the Captain must press the PEDALS DISC Pushbutton on the Steering Handwheel.

The Captain shall apply full sidestick and rudder pedal deflections. The F/O announces the control deflections as they are seen on the ECAM Flight Control Page.

On the F/CTL page, the F/O will check full travel and correct sense of all elevators and all aileron deflections, the correct deflection and retraction of spoilers, and full travel of the rudder. The F/O will call each position only when fully reached. The Captain silently checks that the F/O calls are in accordance with the sidestick or rudder pedal order.

In order to reach full travel, full sidestick shall be held at full deflection for 2 seconds.

Aileron neutral position when flaps are extended is 5 degrees of aileron droop.

When the Captain's flight control check is complete, the F/O shall apply full sidestick deflections, and will silently check full travel and the correct deflection (sense) of all elevators and all ailerons, and the correct deflection and retraction of all spoilers on the ECAM F/CTL page.

[cwatters]

> The airframe vibrations came from the spoilers, that
> started to flutter after the landing flaps were deployed.

Does that imply they were stuck in the deployed or partially deployed position?

[GearDown&Locked]

cwatters, It would be logical that the spoillers would moving between not fully deployed and the almost closed position, as they put the flaps down the air flow above the wing changes modulating the loose spoillers up and down. :eek:

[TyroPicard]

Here's some questions for you.... (I don't know the answers, insufficient data in FCOMs).

How do the engineers disable/enable the ground spoilers? Through CFDS ?
When you press RECALL before start will a GND SPLR FAULT message appear if they are disabled?
If the Ground Spoilers are disabled, as opposed to faulty, will ECAM show amber ground spoiler indications, and when you arm them after start will you receive a GND SPLR FAULT message? If not, why not?

And why would a ground spoiler problem produce a SPLR FAULT message, or is that just sloppy reporting?

And for your interest there is a note in the abnormal procedure for SPLR FAULT.. If heavy vibrations are felt, CONF 3 may be used for landing in order to reduce the buffeting..

[Baron737]

Such failure is far more rare than loss of control through complete loss of hydraulics, which has resulted in fatal accidents.

I didn´t know airbus fbw doesn´t need hydraulics to operate the flight controls :ugh:

[Mad (Flt) Scientist]

Mad (Flt) Scientist, cod liver oil:
The flight control check is done very thoroughly, before every flight. The position of the controls is monitored on the Lower Ecam as the check is done.

Here's how the 320 flight control check might go - no particular airline's procedures, just an example:

Prior to performing the rudder pedal check the Captain must press the PEDALS DISC Pushbutton on the Steering Handwheel.

The Captain shall apply full sidestick and rudder pedal deflections. The F/O announces the control deflections as they are seen on the ECAM Flight Control Page.

On the F/CTL page, the F/O will check full travel and correct sense of all elevators and all aileron deflections, the correct deflection and retraction of spoilers, and full travel of the rudder. The F/O will call each position only when fully reached. The Captain silently checks that the F/O calls are in accordance with the sidestick or rudder pedal order.
In order to reach full travel, full sidestick shall be held at full deflection for 2 seconds.
Aileron neutral position when flaps are extended is 5 degrees of aileron droop.

When the Captain's flight control check is complete, the F/O shall apply full sidestick deflections, and will silently check full travel and the correct deflection (sense) of all elevators and all ailerons, and the correct deflection and retraction of all spoilers on the ECAM F/CTL page.

Hmm. From what I understand of A320 control architecture (and I'll be happy to be corrected) that procedure would seem not to operate the most inboard spoiler panel on each side, which seems to be for ground lift dump only and not commanded by the sidesticks. I retracted my previous comment because I found a specific reference to checking the ground spoilers on another aircrafft.

[guiones]

Hey MAD, you are correct.

From Transport Canada, the spoiler that was left on Maint. mode was #1, so it is not part of the flight control check, only spoilers 2 +

No big deal, some vibration and back on the ground. TC categorized the occurrence as a level 5; no further action.

All the Airbus haters, sorry all your hopes for a flight control problem down the drain, need to keep hoping!!

G

[TyroPicard]

No big deal?
Would the Ground Spoilers (or any spoilers) have worked on an RTO?
Why was there no warning or indication to prevent the crew from taking to the air? (I make an assumption here).

[Dan Winterland]

1. Only the isolated spoiler would have failed to extend.

2. It's a mechanical valve which swithes it into maintenace mode. Airbus obviously assumed the post engineering checks would catch this omission.

Still no big deal.

[PJ2]

TyroPicard;

Transport Canada has classified this as a "level five" event, the lowest "on their radar". You may take from that what you will but the consensus is that it was not a signficant event. I am not in full agreement with that assessment but not wholly for the reasons you state but for the reasons offered below concerning spoilers 2 to 5 and the comments offered in the article below regarding the control check and human factors. This aside noted, the failure to return the valve to the operational position has occurred before so perhaps changes are needed to ensure failsafe completion of maintenance procedures. The vibration felt, (at Config FULL) is an experienced, known item and guidance for same is provided in the AOM. Returning the flaps to Config 3 greatly reduces the vibration for the reasons cited in this thread and controllability is not affected.

The question I would like answered if anyone has specific maintenance knowledge is, will the ECAM "FCTL Spoiler Fault" message appear during the control check if spoilers 2 through 5 are locked out? In my opinion the message will appear but I have been away from the books for a while now. I think, in other words, your comments would be valid if any spoilers, 2 through 5, would be so affected. That does not appear to be the case here but we don't know.

You'll also recall the Lufthansa flight control reversal; the crew kept the airplane under control and landed without incident. There is an article in Avionics Magazine (http://www.aviationtoday.com/av/categories/bga/Safety-in-Avionics-Cross-Wired-Controls_12796.html)which describes the incident. If you can get past the the hyperbole and histrionics of "coming within two feet of crashing", (a remarkably stupid comment for a technical magazine), the latter part of the article is worth reading regarding what actually happened. Also, important questions are asked in the article which is worth quoting in full here. Perhaps it should be noted that the causes of the control fault are substantially different from the Air Canada 320 case:

. . . .

German investigators, Lufthansa officials and representatives from manufacturer Airbus (http://www.aviationtoday.com/search/?query=Airbus) are focusing their inquiry on the maintenance actions that preceded the incident flight. In the process of troubleshooting and repairing an elevator/aileron computer (ELAC–one of two on the A320), Lufthansa Technik personnel found a damaged pin on one segment of the four connector segments (with 140 pins on each) at the "rack side," as it were, of the ELAC mount.


Repair work involving complete rewiring "upstream" of the connector pins was conducted over several work shifts by various technicians. In the process, according to preliminary reports, the polarity inadvertently was reversed on four wires in one connector segment. Two of the wires were for the roll control input and two were for the associated control channel "outputs." It is believed from preliminary accounts that the technicians correctly followed the wiring list. However, BFU officials and maintenance personnel maintained that the wiring lists for individual aircraft may differ. There’s a latent hazard for you, just begging for some technician to perform perfect repairs based on the wrong wiring list.


One pilot observed, "If it were the case that control wiring differed at the ELAC connector between models of the same type, the ELACs would not be interchangeable...and this is not the case." True, but the male/female marriage of connectors and pins (all 560 of them among the four connector segments) is not the issue. Rather, it is the color-coding scheme of the wiring to the backside of the connectors on the rack to which each ELAC is mated.

Before the airplane left the hangar at Frankfurt for return to service, a flight control check was performed using the respective indications on the cockpit ECAM (Electronic Centralized Aircraft Monitoring) display. The BFU confirmed that the mechanic’s flight control check was limited to the first officer’s sidestick, not the captain’s on the left side of the cockpit.

Whether a maintenance technician would be sufficiently astute to catch aileron deflection in the wrong direction is another matter. It is not certain if anyone was standing outside the airplane to double check actual movement of flight control surfaces.


The details of such procedures will be part of the BFU inquiry. The question of any time pressure to get the work done also seems certain to be explored, as well as whether a test flight before the aircraft was returned to service would have uncovered the reversal problem. After all, this was a repair to a primary flight control system (as opposed to a flight management system).

Every crew routinely exercises the flight controls as part of its preflight check. On the A320, the Flight Control page on the ECAM will appear when the sidestick is moved as part of the preflight check. The sidestick must be held about three seconds for full travel to be reached; it takes that long for the ECAM to generate a fault message.


Some confusion exists in the pilot community about whether these checks will be displayed on the ECAM as contro linputs (the position of the sidestick) or control outputs (actual position of ailerons, etc.). The ECAM will display control outputs, as does the comparable system on the Boeing (http://www.aviationtoday.com/search/?query=Boeing) fly-by-wire B777.


One pilot correctly explained the functioning and went on to surmise what may have happened:


"Four position sensors called linear voltage differential transducers (LVDTs–used with aircraft control surface servos) look at the ailerons. This is quite independent of the sidestick positions. This display would not have been affected or reversed because of any miswiring of the sidestick...


"On control checks during taxi out, the pilots saw spoiler movement and aileronmovementin response to commands from each sidestick, correctly displayed on [the] ECAM. It just happened to be in the wrongdirectionfor one stick. Really quite easy to miss at a very busy time, and so unexpected. Every pilot does control checks, thousands of times. It is always correct, isn’t it? Except for this oh-so-rare occasion."


The check often is made during taxi out, a high workload period, rather than before pushback at the gate. Accordingly, the PF is moving his control actuators while keeping his eyes focused on activity outside the airplane, while the PNF is keeping his eyes locked on the ECAM display. In this arrangement, the PNF is not looking at and probably is not able to see the direction in which the PF is testing the sidestick. As such, the PNF may be looking at the ECAM more for confirmation of deflection, but not necessarily for direction of deflection.


In any event, the wiring fault got by at least two safety "filters," as it were. It was not detected during maintenance, and it was not detected during the preflight check.


The fact that this incident did not end with investigators piecing through charred wreckage is fortuitous. In the unfortunate event of a crash, there might not have been sufficient evidence pointing to a connector/wiring fault. Absent such evidence, investigators may have invoked "pilot error" based on a finding of incorrect banking associated with wake turbulence.

To be sure, crossed or reversed flight control cables on conventional aircraft have caused more than one crash. There is a grim history of such events on military and general aviation aircraft. If one control stick is connected backwards, then both yokes are misrigged, and both pilots are faced with the same parlous problem.


However, reversed controls are deemed impossible on transport-category aircraft, with their combination of cables and pushrods. Consider the "conventional" B737. A Boeing (http://www.aviationtoday.com/search/?query=Boeing) official declared it is impossible to reverse the connection of steel cables to hydraulic flight control actuators. Even if done deliberately, the pilots would instantly discover that they could not physically move their flight controls.


In the case of the A320, one aspect of the aircraft’s fly-by-wire design may have enabled the first officer to quickly gain control of the aircraft: the ability to isolate a malfunctioning sidestick and shift command to the other sidestick at the push of a button. As one pilot noted: "I would say that on this occasion, it was because of Airbus technology that a major incident was avoided!"


That may be so. But the case may well illustrate how avionics protections against human error in the cockpit can be reversed into outright hazards by human error on the maintenance floor. The BFU may have "just" an incident on its hands to investigate, but the safety issues are profound.

[Tree]

All the Airbus haters, sorry all your hopes for a flight control problem down the drain, need to keep hoping!!


Thanks but hoping is not necessary as we already do have control problems:
1. Crosswind incidents
2. Overrun incidents due ground spoilers cannot be manually extended
3. A321 incidents in icing conditions (certified without actual flight testing)

[Iceman49]

Agreed, Airbus builds an incredible aircraft, I know of no problems with the 321 and icing, personally find it an easy aircraft to control in x-winds...and as PJ2 said...overruns are not an Airbus problem.

[PJ2]

Mad (Flt) Scientist;

The information I have, and it is not based upon experience as I am not an engineer or a wrench, is that the 320 AMM cautions that the lockout valve "hex" is fully turned to the "M" position to prevent aerodynamic forces from raising the spoiler, so I assume that the spoiler can be physically locked down, (which only makes sense). Also, apropos the testing of the spoilers when buttoning up only one sidestick is required to be used for testing the spoilers.

We are assuming as well, that the indications for spoiler deployment on the FLT CTL lower ECAM page indicate actual position of the spoiler and nothing else; I raise that point because of comments in the Avionics article posted above regarding indications. Also, (and I thought this had been fixed), the requirement to hold the sidestick in position for at least 2 seconds, (some documents say 3), so give the servos time to reach full travel. Care must be exercised here as well as in actually seeing the ECAM indications, (as opposed to mentally "looking through" the indications because the control check is done so often) - what can appear correct, may not be as was the case with the Lufthansa crew. So there is lots to this, though not all (if even most) may (or may not) apply to the AC case; we just don't have enough information, nor, likely, will we unless it comes from Transport Canada or the CTSB.

[Tree]

Well, post what you will; - It's easy enough to say in an anonymous forum

Yes I will thank you. One of the basic foundations of flight safety is the passing of information without fear of reprisal from the employer, manufacturer or state. We could also include attempted stifling or ridicule by other pilots. History has long ago proven that the anonymous safety reporting system is one of the reasons for the high level of safety today in the industry. More recently we see it in the de-identified FOQA programs.

What is being expressed here is plain old prejudice and not an airman's knowledge or experience.

I will be sure to let the TSB know what you think of their factual analysis of incidents in this report:
Transportation Safety Board of Canada - AVIATION REPORTS - 2002 - A02O0406 (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2002/a02o0406/a02o0406.asp)

I'm going to copy a few highlights for those who will not read or comprehend all of it:
Modifications to the A321 ELAC software were made after a landing occurrence in February 2001 in which there was wing-tip damage. This occurrence also involved roll oscillations in a significant crosswind but with no icing.
Findings as to Risk
1.Flight tests in natural icing conditions were not accomplished in any configuration in the A321 to determine if an acceptable level of safety existed in the handling characteristics.

[Servus !]

@ fc101

The cables on the 777 are not driven by computers. There are cables from the flight deck to the stabilizer and to Spoiler #4 and #11. With the cables you are able to keep the AC straight and level until you have re-established electrical power

[scarebus03]

So does this mean the AB bashing is finished? Many maintenance mistakes have been made on every type of machine in the air and indeed used anywhere else. It appears to be down to human factors and it is not the first time that this has happened with the A320.

When you lockout the spoilers on the A320 you install a collar with a flag 'REMOVE BEFORE FLIGHT' which in theory remains with the spoiler actuator and can only be removed from the keyway when the spoiler is reactivated IF YOU USE THE CORRECT TOOLING.

It has happened in the past that an alternative procedure has been used when the tools were not available and the result was something similiar. It happened to a G-KMAM Excalibur airways aircraft some years ago but I don't remember the exact details.

Brgds SB03

[aguadalte]

If the ground spoilers were indeed left in maintenance mode, wouldn't the crew have noticed this during their pre-departure flight control checks?

just curious

Yes, there would be amber crosses (in step of the spoiler number) appearing on the FLT CTRL Lower ECAM page and most certainly a HIL would have been open by MAINT guys on the Technical Log Book.

How do the engineers disable/enable the ground spoilers? Through CFDS ?
When you press RECALL before start will a GND SPLR FAULT message appear if they are disabled?
If the Ground Spoilers are disabled, as opposed to faulty, will ECAM show amber ground spoiler indications, and when you arm them after start will you receive a GND SPLR FAULT message? If not, why not?

And why would a ground spoiler problem produce a SPLR FAULT message, or is that just sloppy reporting?

I'm responding to this one by memory, since I'm on a layover and I have no Manuals available with me.
(If someone knows it better or wishes to make a correction, please do so. I'm using commas when I don't recall the exact names)

Spoilers are mechanically disabled by Maintenance. The process takes about half an hour to 45 minutes. There is a switch in each Spoiler that has to be put in "maintenance position" in order to move it to its closed position and only then it is "locked", in order to keep its retracted position, during flight. I think a "socket" has to be disconnected and therefore amber crosses will appear on ECAM. The opposite side Spoiler must also be disabled.
You will get a SPLR FAULT ECAM Message, as soon as you start-up your first engine, (although amber crosses are always present on the ECAM page before, and after, your start-up).
The STATUS Page will also give a PART SPLRS message, (every time you call that page and) as a recall, as soon as one selects FLAPS 1 for approach.
I don't recall the A320 fleet, but I'm sure it’s the same philosophy. The MEL allows us to take-off with two (pairs) of inhibited spoilers. Penalties are not appalling for just one (pair) off, but may represent lesser payload for the worst case. Penalties also increase in case one decides to use Flap 3 for landing.

I think the system it self is well designed but becomes problematic in case your Maintenance Engineers forget to lock one (or more) of your disabled Spoilers, leaving it in the “Maintenance Position”, therefore receiving hydraulic pressure, but only retracting aerodynamically. In that particular case, the Pilot has no way to know (except visually), that one of his disabled spoilers is in fact receiving hydraulic pressure (and moving up) once the ECAM System Pages will show him amber crosses! Also, since he is flying a FBW aircraft, he will not feel the need for trimming, because the system will automatically compensate for the not retracted spoiler. When you get a SPLR FAULT ECAM message, you will get an amber indication on the FLT CTRLS Page, together with the number of the Spoiler, and if the SPLR is not retracted you will get an arrow showing the faulty one UP.
In the disabled spoiler case, one gets nothing except, aerodynamically induced vibration, higher fuel consumption, a less performant aircraft, and may be some sideslip indication. I find here that there is space for Airbus Industrie to improve this design, although I’m not confident they will. All we would need, is that arrow showing the aviator that, one of his disabled Spoilers is out of the retracted position…
Fly Safe

[guiones]

Tree:

I would like to know how close you have been to flying an Airbus FBW to make such a statement.

My guess, not even close!!!

I speak from experience; can you say the same??

G

[Tree]

guiones; I speak from experience; can you say the same??


Affirmative..

[guiones]

Tree:
You did not answer, is your experience on Airbus FBW, and please as you say for safety's sake; share with us the problems YOU have experiencenced on Airbus FBW.

G

[grizzled]

"So does this mean the AB bashing is finished?"

Now that's funny!

The bookies will give you the same odds on that as they will on a comet wiping out civilisation in the next 12 months.

Airbus bashing -- and the airbus v/s boeing debate -- will not end 'til the comet hits.

;)

[fc101]

Servus ! :

The cables on the 777 are not driven by computers. There are cables from the flight deck to the stabilizer and to Spoiler #4 and #11. With the cables you are able to keep the AC straight and level until you have re-established electrical power

Actually didn't know that specific fact about the 777...however the 777 is effectively flown by computer, in that, AFAIK, it is considered a FBW aircraft. In this sense the A320 is similar in that the vert stabiliser is similarly controlled (AFAIU*)

Basically, what I'm referring to is that very early on in this discussion someone was already spoiling for an AvB argument with the response: Airbus bad, Boeing good....for no other reason than dogma :-) I'd just been given an AvB lecture by a similarly knowledged person and so wasn't in the best mood at the time as far as I remember...

I think I'll wait for the aforementioned comet to hit...

MODS: can we have a generic AvB post here somewhere to save space that we can all reference when these moments it?

*I'm not an A320 driver, yet! So go easy...

fc101
E145 Driver

[Wirelock]

think that would be the trimmable horizontal stabilizer that you mean. this and the landing gear cable are the 2 on the 320

[TyroPicard]

Don't forget the rudder ("vert stabiliser"?) cables...