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Qantas Talks Straight On Airbus Problem  
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Posted (4 years 6 months 1 week 5 days 14 hours ago) and read 20303 times:

http://www.abc.net.au/news/stories/2...10/15/2715032.htm?section=business

Qantas says it is working with the manufacturers of the Airbus A-380 to fix a flight stability problem with one of the super jumbos it has on order.

Does this problem affect only this aircraft or is it affecting all QF A380s or all A380s or what???

"What can happen is the aircraft can start to oscillate in a figure eight pattern, but you try to avoid all those things with your aircraft having an effective trim system."

Seems a bit odd for a trim problem to show up now.

43 replies: All unread, showing first 25:
 
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 1, posted (4 years 6 months 1 week 5 days 14 hours ago) and read 20223 times:



Quoting Baroque (Thread starter):
Seems a bit odd for a trim problem to show up now.

Sounds like "pod nod". The engines oscillate around in small circles causing the entire airframe to feel unstable.


User currently offlineFrancoflier From France, joined Oct 2001, 3613 posts, RR: 11
Reply 2, posted (4 years 6 months 1 week 5 days 13 hours ago) and read 20018 times:

Too bad the article is so vague and absolutely not telling of the actual problem (as usual).

This article seems to indicate that the problem is limited to their fifth frame not the whole fleet, which is why the delivery has been delayed:

http://www.watoday.com.au/travel/tra...elivery-delayed-20091015-gy2j.html

"The airline confirmed the 450-seat jet would need to undergo further tests at the Airbus factory in Toulouse.

However, Qantas dismissed talk that its number five A380 could not stay straight while on auto-pilot.
"

But again, not a lot of concrete information.



Looks like I picked the wrong week to quit posting...
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 3, posted (4 years 6 months 1 week 5 days 12 hours ago) and read 19787 times:



Quoting 474218 (Reply 1):
Quoting Baroque (Thread starter):
Seems a bit odd for a trim problem to show up now.

Sounds like "pod nod". The engines oscillate around in small circles causing the entire airframe to feel unstable.

Good god!!! Never heard of that. Wonderful name though. Is it a basic design problem or more a one off that is at tolerance limits (or whatever)??

Quoting Francoflier (Reply 2):
Too bad the article is so vague and absolutely not telling of the actual problem (as usual).

Not wrong there Francoflier. I am getting more and more irritated with how little media releases actually tell you. And this is the sort of rubbish that Murdoch now thinks we all NEED to pay for! Mind you my quotes came from the ABC who have specifically told Murdoch he is dreaming.


User currently offlineAirvan00 From Australia, joined Oct 2008, 745 posts, RR: 1
Reply 4, posted (4 years 6 months 1 week 5 days 9 hours ago) and read 19217 times:

I stand to be corrected but QF's 5th A380 has only had two flights, its first flight ( back in March) and its ferry flight to XFW. Last I heard that aircraft was still having the cabin fitted and had yet to start its flight tests. Maybe the article is referring to another aircraft.

User currently offlineQFFlyer From Australia, joined Jun 2005, 368 posts, RR: 0
Reply 5, posted (4 years 6 months 1 week 5 days 9 hours ago) and read 19147 times:

The issue is that it is flying "wing down", but within tolerances. Really interesting to hear the details, and that it is better [more efficient] to leave it as it is than trim via flaps. I think the issue is that MSN27 is closer to the tolerance edge than other frames.

Cheers


User currently offlineAerdingus From Ireland, joined Dec 2006, 2761 posts, RR: 15
Reply 6, posted (4 years 6 months 1 week 5 days 7 hours ago) and read 18666 times:

http://www.flightglobal.com/articles...ayed-due-to-flight-trim-issue.html

All I kept thinking as I read this article is how Qantas continue to be scruitinised by the media. I mean, fair enough they are explaining the delay of the latest aircraft, but would the general public even have been aware of deliveries etc? Is it a fairly fixable problem?



Cabin crew blog http://dolefuldolegirl.blogspot.ie/
User currently offlineScbriml From United Kingdom, joined Jul 2003, 12048 posts, RR: 47
Reply 7, posted (4 years 6 months 1 week 5 days 6 hours ago) and read 18314 times:
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Quoting Baroque (Reply 3):
Is it a basic design problem or more a one off that is at tolerance limits (or whatever)??

One would have to assume the issue would have been noticed before now if it were "endemic" (or should that be pandemic?)



Hey AA, the 1960s called. They want their planes back!
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 8, posted (4 years 6 months 1 week 5 days 5 hours ago) and read 17313 times:



Quoting Scbriml (Reply 7):
Quoting Baroque (Reply 3):
Is it a basic design problem or more a one off that is at tolerance limits (or whatever)??

One would have to assume the issue would have been noticed before now if it were "endemic" (or should that be pandemic?)

Perhaps it is the latter, we seem to be having a new outbreak of the swine flu - especially among the swine as it happens.  Big grin

Quoting QFFlyer (Reply 5):
The issue is that it is flying "wing down", but within tolerances. Really interesting to hear the details, and that it is better [more efficient] to leave it as it is than trim via flaps. I think the issue is that MSN27 is closer to the tolerance edge than other frames.

Aha. Sounds like a good explanation of the otherwise Delphic press statements. Dare one ask where you came by that information, or would I have to be killed (too)?


User currently offlineTISTPAA727 From United States of America, joined May 2007, 319 posts, RR: 2
Reply 9, posted (4 years 6 months 1 week 5 days 4 hours ago) and read 16632 times:

If this is only impacting one frame and no other airlines have complained about it, this could be the effect of the manufacturing process on just this one frame and nothing more. Has anyone else heard other airlines mention this? If this were a design issue Airbus would have caught it long ago - they've got some pretty smart people over there!


Don't sweat the little things.
User currently offlineMotopolitico From United States of America, joined Dec 2005, 212 posts, RR: 0
Reply 10, posted (4 years 6 months 1 week 5 days 3 hours ago) and read 15506 times:

Even though it is "within tolerances", wouldn't this be a sign that Airbus isn't entirely in control of their process? Or is this frame one of the ones built before the production was standardized? I wonder how noisy the "mean performance" of a380 is. Is the tolerance three sigmas? What variances in production could account for an airframe that had such outlying performance? Really, I'm more interested in the statistics side of things than in criticizing anyone. Also, what does "wing down" mean? Is that like Attitude Nose Down, or does it refer to the dihedral?


Garbage stinks; trash don't!
User currently offlineManfredj From United States of America, joined Mar 2007, 1132 posts, RR: 0
Reply 11, posted (4 years 6 months 1 week 5 days 3 hours ago) and read 14911 times:

Sounds like the "dutch roll" problem the 707 used to have. I remember my father telling me a story about his KC135:

The aircraft yaws and rolls in a back and fourth motion. The motions would build up then become exasperated with any attempt to fix it. Part of their simulator training included "recovery from a dutch roll." At that time a damper system was developed and the problem went away.

I too am interested to know if it is particular to just this aircraft. Is it common for the airline to go on the test flights? Is this something they could pick up on just one flight as the motion seems to be hard to detect.

Terrible article by the way.



757: The last of the best
User currently offlineRB211TriStar From United States of America, joined May 2007, 185 posts, RR: 0
Reply 12, posted (4 years 6 months 1 week 5 days 2 hours ago) and read 14500 times:



Quoting Motopolitico (Reply 10):
Even though it is "within tolerances", wouldn't this be a sign that Airbus isn't entirely in control of their process? Or is this frame one of the ones built before the production was standardized? I wonder how noisy the "mean performance" of a380 is. Is the tolerance three sigmas? What variances in production could account for an airframe that had such outlying performance? Really, I'm more interested in the statistics side of things than in criticizing anyone

If the airframe was produced within tolerance, then by definition Airbus has control over their processes. The size of the tolerance would determine how controlled the process is, however I can tell you that no manufacturer (not Toyota, or Motorola, or Honda, or Airbus for that matter) will ever divulge their process control metrics to industry. They might say "We operate at 5.5 Sigma" but I guarantee it would all be marketing fluff.


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3328 posts, RR: 4
Reply 13, posted (4 years 6 months 1 week 5 days 2 hours ago) and read 14254 times:



Quoting RB211TriStar (Reply 12):
They might say "We operate at 5.5 Sigma" but I guarantee it would all be marketing fluff.

Yah, and a manufacturer can make a joke out of it. My truck should be be 15ft long +-1ft. could you imagine NOT getting one off the line that meets that tolerence?


User currently offlineAstuteman From United Kingdom, joined Jan 2005, 9841 posts, RR: 96
Reply 14, posted (4 years 6 months 1 week 5 days 2 hours ago) and read 13960 times:
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Quoting TISTPAA727 (Reply 9):
If this were a design issue Airbus would have caught it long ago - they've got some pretty smart people over there!

It's entirely possible to make a design more, or less, tolerant of tolerance build-up - there is a relationship between manufacturing tolerances, and the overall design.

Quoting Motopolitico (Reply 10):
Even though it is "within tolerances", wouldn't this be a sign that Airbus isn't entirely in control of their process?

If it's within tolerance, then by definition, Airbus are in control of their processes.

I just wonder if there's some susceptibility of the airframe to this trimming issue at a given tolerance build-up..
It's extremely curious that just one airframe (as far as we know) has exhibited the reported characteristic.

Rgds


User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4482 posts, RR: 22
Reply 15, posted (4 years 6 months 1 week 5 days 2 hours ago) and read 13887 times:

Could this be as simple as a yaw damper issue? The article is so vague it's hard to tell if it's just the one delivery or the entire fleet. Based on the very loose description of the squawk in the article it seems like it's exhibiting a little Dutch roll.


I got my head checked--by a jumbo jet
User currently offlineManfredj From United States of America, joined Mar 2007, 1132 posts, RR: 0
Reply 16, posted (4 years 6 months 1 week 5 days 1 hour ago) and read 13245 times:

Quoting JBirdAV8r (Reply 15):
Based on the very loose description of the squawk in the article it seems like it's exhibiting a little Dutch roll.



Quoting Manfredj (Reply 11):
Sounds like the "dutch roll" problem the 707 used to have.

That was my first impression JBird, but I wish the article stated whether it was specifc to this airplane....in which case you could probably rule it out. I'd also like to know if it only happens when autopilot is flying the aircraft.

[Edited 2009-10-15 09:02:57 by manfredj]


757: The last of the best
User currently offlineMax Q From United States of America, joined May 2001, 4089 posts, RR: 19
Reply 17, posted (4 years 6 months 1 week 5 days 1 hour ago) and read 12942 times:



Quoting QFFlyer (Reply 5):
that it is better [more efficient] to leave it as it is than trim via flaps.

You don't trim with flaps QF, trim is accomplished longitudinally with the trim switches on the control yoke repositioning the Horizontal Stabilizer.


In the Yaw axis trim is controlled by adjusting the Rudder Trim, this is normally controlled with a small 'wheel shaped' knob on the rear of the control pedestal that readjusts the 'Null point' of the rudder.



In the roll Axis Aileron trim is adjusted with a small wheel or vertical split switches on the pedestal and will deflect the control surface (and spoiler angle) to provide roll trim.


The objective with a well trimmed Aircraft is to allow it to fly 'hands off' with the Autopilot disengaged and no 'slip or skid' so that the Aircraft is 'going straight' through the air, rather like having all the wheels on your car perfectly aligned.


Not being in trim will cause drag and increased fuel burn.


It doesn't sound like a Dutch Roll problem in this case but more of a question of this particular Aircraft being 'out of rig' an example of this would be one wing being a a slightly different angle to the Airframe than the other.



In most cases these differences are insignificant and can 'be trimmed out' in flight (most aircraft are a little 'bent' especially older ones) but a really crooked Airframe may need rework performed by the manufacturer.



The best contribution to safety is a competent Pilot.
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Reply 18, posted (4 years 6 months 1 week 5 days ago) and read 11439 times:



Quoting Max Q (Reply 17):
You don't trim with flaps QF, trim is accomplished longitudinally with the trim switches on the control yoke repositioning the Horizontal Stabilizer.

I flew on a 727 in which the wing tab I could see out my window (tab between inboard and outboard flaps) was slightly extended downwards. I asked and was told this was to compensate for a slight imbalance that was causing the plane to roll slightly to the right.

Here is one extended slightly up: http://www.airliners.net/photo/Aero-...d=9e9531475e9f11347d2e91a6b3f3a789

I don't know if that explanation was accurate but it sounded reasonable to me at the time.


User currently offlineVoar From Canada, joined Jul 2008, 95 posts, RR: 0
Reply 19, posted (4 years 6 months 1 week 4 days 23 hours ago) and read 10972 times:



Quoting Max Q (Reply 17):

You don't trim with flaps QF, trim is accomplished longitudinally with the trim switches on the control yoke repositioning the Horizontal Stabilizer.

It doesn't sound like a Dutch Roll problem in this case but more of a question of this particular Aircraft being 'out of rig' an example of this would be one wing being a a slightly different angle to the Airframe than the other.

In most cases these differences are insignificant and can 'be trimmed out' in flight (most aircraft are a little 'bent' especially older ones) but a really crooked Airframe may need rework performed by the manufacturer.

Actually for a permanent out of trim such as you describe due to the aircraft being slightly crooked, sometimes the flaps are adjusted to be slightly different to compensate. Piper aircraft use this technique of flap adjustment, where as Cessna piston singles usually can have one wing's incidence adjusted slightly. In the case of a large aircraft the incidence is obviously not adjustable, it is entirely possible a slight flap deflection could be used to cure any rolling trim permanently if that is the case. Big problem though would be a slight fuel burn increase for the particular aircraft.

I don't think this was the case however by what is described in the article. Seems like some sort of other unexpected aerodynamic oscillation occurring. I doubt it is dutch roll as this is a well understood phenomena and is certainly accounted for early in the design of the aircraft.


User currently offlineMax Q From United States of America, joined May 2001, 4089 posts, RR: 19
Reply 20, posted (4 years 6 months 1 week 4 days 23 hours ago) and read 10780 times:



Quoting Khobar (Reply 18):

I flew on a 727 in which the wing tab I could see out my window (tab between inboard and outboard flaps) was slightly extended downwards. I asked and was told this was to compensate for a slight imbalance that was causing the plane to roll slightly to the right.

What you were looking at there was the inboard, high speed Aileron and yes, this would be deflected downward to prevent a rolling moment to the right. The control yoke would also be displaced to the left in this case.


This is not an ideal, trimmed condition, we always trained to 'zero out the yoke' in other words use rudder trim in the direction of yoke displacement for a 'level control yoke'



By doing this you will mostly eliminate Aileron and more importantly, spoiler drag which deflect with large yoke angles causing significant drag and fuel burn.

Quoting Voar (Reply 19):

Actually for a permanent out of trim such as you describe due to the aircraft being slightly crooked, sometimes the flaps are adjusted to be slightly different to compensate. Piper aircraft use this technique of flap adjustment, where as Cessna piston singles usually can have one wing's incidence adjusted slightly. In the case of a large aircraft the incidence is obviously not adjustable, it is entirely possible a slight flap deflection could be used to cure any rolling trim permanently if that is the case. Big problem though would be a slight fuel burn increase for the particular aircraft

Good point and a very valid one, the impression I got from Qf's post was the thought that flaps would be deployed in flight to help trim out the Aircraft.



The best contribution to safety is a competent Pilot.
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 21, posted (4 years 6 months 1 week 4 days 22 hours ago) and read 9929 times:



Quoting Max Q (Reply 17):
In most cases these differences are insignificant and can 'be trimmed out' in flight (most aircraft are a little 'bent' especially older ones) but a really crooked Airframe may need rework performed by the manufacturer.

Airplanes have allowable build tolerances, since you can not be expected every part of every plane to be exactly the same. So there is always the possibility that the wings, vertical and/or horizontal stabilizers may be off by a small amount. Therefore during the flight testing of each individual aircraft the hands free trim for that aircraft is established. After establishing where the aircraft flys straight and level and the plane lands, the roll and yaw trim have a new null point established, the trim wheels are set to zero but that amount of trim required for straight and level flight is left in.


User currently offlinePlaneInsomniac From Canada, joined Nov 2007, 647 posts, RR: 0
Reply 22, posted (4 years 6 months 1 week 4 days 22 hours ago) and read 9626 times:



Quoting JBirdAV8r (Reply 15):
The article is so vague it's hard to tell if it's just the one delivery or the entire fleet.

Frankly, the article is pretty clear about this. The problem is with one specific plane:

to fix a flight stability problem with one of the super jumbos it has on order

The airline's fifth A-380 was due to arrive at the end of this month but its arrival has now been put off

So, it is not the entire fleet which is affected, and it certainly is not a general A380 problem.

Still, it makes you wonder if there aren't some QA issues on the Airbus side.



Am I cured? Slept 5 hours on last long-haul flight...
User currently offlineRB211TriStar From United States of America, joined May 2007, 185 posts, RR: 0
Reply 23, posted (4 years 6 months 1 week 4 days 21 hours ago) and read 9366 times:

Frankly, I don't understand why any of this is news. Does an article get published every time A or B installs a part that needs tweaking?

"Airbus considers installing shim to level out business class seat. Film at 11."  nosy 


User currently offline413X3 From United States of America, joined Jul 2008, 1983 posts, RR: 0
Reply 24, posted (4 years 6 months 1 week 4 days 21 hours ago) and read 9146 times:



Quoting RB211TriStar (Reply 23):
Frankly, I don't understand why any of this is news.

News reports events that happened. This happened, right? So then it is news


25 Slz396 : Its reported because its related to an A380... We've seen everything related to this plane being reported, from the simple replacement of a strobe li
26 EbbUK : .... and there piss all news on the aviation front. God it is dull. 2yrs ago we were posting orders orders orders. Who paid attention to deliveries o
27 RB211TriStar : It was more of a rhetorical question... but I agree with you.
28 Revelation : Sure. Airbus made a lot of noise about the A380 so it's natural a lot of public interest has built up around the plane. Besides, UK, FR, DE and ES ta
29 EbbUK : Piffle and codswallop. A slightly delayed A380 is hardly going to rock the balance of payments in any of the economies that you mention.
30 Revelation : Right, but it does help explain the interest the folks buying the newspapers have. Otherwise, why waste the newsprint?
31 Francoflier : I think it's more a case of the 'Aussie press+Qantas+A380' syndrome.
32 QFFlyer : You may ask but out of repsect, and wanting the information to keep coming....I don't think its wise. I understand most A380s actually want to fly "w
33 Baroque : Thanks. That certainly makes a deal more sense than the dumb press and ABC pieces!! What time should I expect the assassination squad around tonight,
34 Astuteman : I would have said they're lenders, rather than investors. As are a number of other establishments.... Find that hard to believe. It's newsworthy beca
35 CHCalfonzo : Just a quick question here. What exactly is the sigma notation? In my experience epsilon has been used to represent the tolerence for a calculation,
36 Astuteman : Sigma is a statistical standard deviation. " "X" sigma quality" is an expresssion of how many times the manufacturing process can be expected to oper
37 SEPilot : It depends on how Airbus handles assembly tolerances. On most assemblies that I have worked on, tolerances are held on the individual parts, and thos
38 EPA001 : Well, that looks appealing to me but I am sure it is not every bodies preferred coffee here on A-net. On: it seems like a minor issue, but of course
39 Revelation : Maybe you do, but on the other hand, now that my tax dollars are propping up GM I pay a lot more attention to what GM does. IIRC FR owns 17% of EADS
40 Astuteman : Ah. That'll be the difference..... Rgds
41 Burkhard : Isn't that what testing is for? Every plane gets tested, a list of issues presented, issues get fixed, tested again, when all is OK plane gets taken?
42 Revelation : Indeed. Your government seems to be better at picking which companies it will prop up. Hopefully with time GM will be as healthy as EADS now is, and
43 Revelation : Indeed, but it seems this flaw was found so late in the cycle as to delay delivery. Usually you hope to catch things earlier so you can develop the f
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