Moderators: jsumali2, richierich, ua900, PanAm_DC10, hOMSaR

 
User avatar
SEPilot
Posts: 5753
Joined: Sat Dec 30, 2006 10:21 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 8:04 am

Quoting RedChili (Reply 92):
Do you consider Zeke to be a prophet? Wink

I believe the first CX 77W will be delivered in September this year.

I did not realize that; I thought they already had them. No, I don't consider Zeke to be a prophet but I do respect his opinion (although I also disagree with him at times.)
 
User avatar
sunrisevalley
Posts: 5392
Joined: Tue Jul 06, 2004 3:26 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 10:28 am

Zeke......So if I fly JFK-HKG about October 23rd what are the odds that you will be part of the crew?
 
User avatar
jetmech
Posts: 2391
Joined: Wed Mar 29, 2006 2:14 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 1:47 pm

Quoting Zeke (Reply 86):
You can do anything you like, you can have whatever distribution you like with a manual load, which one may have to do for some MEL items, so I cannot see why you cannot do it for some loading configurations.

G'day Zeke  Smile,

What you say here is quite true. I could do a full manual refuel of an A330 / A340 and put the fuel onboard at any distribution I liked, but I'm sure that the aircraft would strongly register it's objections via many warnings, bells, sirens and whistles!

I can't recall ever doing a full manual refuel on an A330 / A340 in all the years I have been working on them. Nonetheless, even if I did do a full manual refuel ( like I always used to do on 747's ), I would have to refuel to a given standard or non-standard (MEL) distribution. I don't recall ever hearing of any mechanic or engineer refuelling to a "custom" distribution unless she or he had several layers of authority above them giving them the OK (ie, manufacturer, government and airline). An example of this was the changes to the 747 fuel distribution in the wake of the TWA tragedy.

As you suggest, adding more fuel to the stab tank would certainly be a "fix" for the problem, but as I mentioned in my previous post, it seems that the stab tank is fuelled to a fixed function of the total fuel onboard the aircraft. I'm not sure if the C of G position comes into play at the refuelling stage. I was curious as to whether you knew if the C of G affected the refuelling distribution?

I have no doubts that Airbus could develop a new refuel distribution with extra stab tank fuel to compensate for the supposed forward C of G of the A346. What I was doubting in my original post was the ability of the airlines themselves to develop this change. I am sure that the airlines have many highly qualified engineering personnel at their disposal, but the full implications of such a change could only be fully appreciated and understood by Airbus themselves. No airline would risk such an important change without Airbus's OK.

Regards, JetMech
 
ikramerica
Posts: 15188
Joined: Mon May 23, 2005 9:33 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 2:34 pm

Quoting Trex8 (Reply 97):
your description is spot on and I do take it into account but he still has technical insight into things most of us are clueless about and have no real world experience with.

One can use that technical insight to one's advantage in an argument by claiming certain things that can't be verified and go against the realities of the market as "inside" numbers. but since it's "real" knowledge it can't be questioned.

we see it all the time from people who claim to know inside knowledge about fleet decisions at VS or QF, etc. because they were working for them or closely with them, and then the reality turns out to be very different.
 
Rheinbote
Posts: 1103
Joined: Sun May 21, 2006 9:30 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 7:49 pm

Quoting JAAlbert (Reply 54):
So is the 340 really extremely fuel inefficient?

Depends on your standards. In commercial aviation terms, a 10% difference in fuel burn (everything else being equal) is a lot. Leahy conceded that the 3456 has a 'single-digit penalty' in fuel burn vs the 773ER/7772LR. If that claim is anywhere near the truth, it got to be at least 9%. My guesstimate would be 10-12% for the number of engines alone, plus a about 4-5% for the difference in OEW for comparable layouts.

This source provides a good overview. I'm not inclined to check the figures for 'accuracy' let alone provide 'more accurate figures' on Easter Monday. Only so much: The weight figures are outdated and have developed to the detriment of the 340. The economic assessment is taking into account the A340's extra cargo capacity versus the 777, but if that capacity would be limited due to a foward CG issue, this would indeed ruin the balance, even at 2001(!) fuel prices as used in this source. http://www.aircraft-commerce.com/sto.../Flight%20Operations,%20Sample.pdf

While this reference IMO is exaggerating a little, it gives a good feeling what the fuel burn numbers alone mean in terms of life cycle cost:
http://iagblog.blogspot.com/2006/01/...us-to-offer-cash-back-on-a340.html

Edited for clarity

[Edited 2007-04-09 13:01:19]

[Edited 2007-04-09 13:09:35]
 
OldAeroGuy
Posts: 3928
Joined: Sun Dec 05, 2004 6:50 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 9:23 pm

Quoting Rheinbote (Reply 107):
This source provides a good overview. I'm not inclined to check the figures for 'accuracy' let alone provide 'more accurate figures' on Easter Monday. Only so much: The weight figures are outdated and have developed to the detriment of the 340. The economic assessment is taking into account the A340's extra cargo capacity versus the 777, but if that capacity would be limited due to a foward CG issue, this would indeed ruin the balance, even at 2001(!) fuel prices as used in this source. http://www.aircraft-commerce.com/sto.../Flight%20Operations,%20Sample.pdf

Payload range data are also badly out of date. Both airplanes fly about 7900 nm for the design mission (pax and bags only). The A346IGW does not have the payload range advantage over the 773ER quoted in the article. Therefore the article's claimed A346 cargo advantage does not exist prior to accounting for any forward CG issues.
 
DAYflyer
Posts: 3546
Joined: Wed Sep 08, 2004 9:35 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 9:40 pm

Quoting Teva (Reply 4):
So, if airlines decide to install heavier equipment on the main deck of their nose section, it automatically reduces by the same amount the weight you can put in the holds just under. This is just to keep the aircraft in balance with the rear section.

Unless Airbus misrepresented to the airlines what they could or could not do...
 
Dougloid
Posts: 7248
Joined: Tue Jul 05, 2005 2:44 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 10:28 pm

Quoting Trex8 (Reply 82):
the MD11 is IMHO not a good comparison as MDC just simply didn't hit their projected fuel burn performance figures at all when the MD11 entered service. the A345/6 problem is not that they are way off what was projected, its that with fuel prices as they are, the even a small difference compared to the 77W easily swings the operational costs in the 777s favor.

For some reason, despite all the facts to the contrary people insist on characterizing the MD11 and DC10 as failures. They got bad press back in the day because of some well known fatal accidents. Lest we forget Swissair lost one because of a cockpit fire that started as an electrical malfunction. Could it have been saved? I don't know. .

An example. One time back when I had money me and the Dragon Lady are going somewhere and she says "Oh! I'd never fly on a DC10....they're well known to be unsafe. I saw it on CBS news." So I say, what about this plane? "Oh!" says she, this is nice and smooth and quiet." I say, "Do you know what you've been riding in the last three hours?"

Major Edwin Armstrong said it best. What people know isn't dangerous-it's what they know that ain't so that is.

quote=BoogyJay,reply=59]I think this is an airline issue here, as all data are available in the Weight & Balance Manual. The A346 could possibly be too restrictive as to CG, but the airlines accepted to buy the aircraft based on the specs Airbus gave them.
Of course, this is a totally different issue if Airbus did...[/quote]

I'd say the key question here is whether the heavy CFE up front is being installed on new aircraft at the factory by the factory or whether this is an after delivery retrofit by the airlines. If it's the former, then perhaps the airlines may have an argument here if they're willing to confess to stupidity and lack of independent oversight, namely, reluctance to hire a competent weights engineer, and routinely tossing everything from Airbus weights in the trash.. That's not unheard of. A lot of corporate operators would pull the same stunts when their 731 Jetstars were being delivered: "What?! You never told me anything about this!" Well, of course we did. They just weren't listening.

Weight and balance is a subject nobody wants to hear about until it's too late. This is spoken as a former weights engineer.

On the other hand, if the installations that triggered this latest fiasco took place after the aircraft were delivered, why, the airlines have nobody but themselves to blame. If you buy a Chevy Biscayne and the frame breaks because you loaded four tons of anvils in the trunk, don't blame General Motors unless they told you you could do it.

Now. The horizontal stab on the Airbus has fuel in it like the Md11 did. This is for purposes of trimming the CG in flight to the aft end of the range-it makes for better fuel economy, but it comes at the expense of some stability. That's why they do it.

This story in the press of "pushing the nose down in flight" is preposterous. What I'm getting is that Airbus has told people that excessive weights in the forward part of the aircraft could create a situation where it is possible to load the aircraft out of the CG range, and that therefore they need to restrict the amount of baggage or cargo loaded in the forward hold. That in itself is not unusual.
 
User avatar
PA110
Posts: 1993
Joined: Sat Dec 06, 2003 1:30 am

RE: Carriers Consider Suing Airbus Over A346 CG Is

Mon Apr 09, 2007 11:02 pm

Quoting Brons2 (Reply 93):
An A346? No, I don't think so. An A346 could not fly the mission you described.

This is exactly the problem with civ av. Some "know it all" armchair pilot trying to lecture an actual pilot.

This thread has been fascinating, and many thanks to Zeke, and others who have contributed actual experience. Brons2 and Jetfan727 would do well to just take a back seat and listen and learn from the professionals, instead of shooting their mouths off.
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 09, 2007 11:17 pm

Quoting Zeke (Reply 86):
Had a look at some figures from a past trip I did, taking off at MTOW our GWCG was about 25%, the forward limit is about 18%, aft limit is about 35%, in cruise with the fuel transfer and automatic CG control to reduce fuel burn, the CG remained at about 33%.

Payload, zone load, compartment load?

Quoting Zeke (Reply 86):
Went back at my notes, for a ULH flight taking off at MTOW we averaged about 8.8t per hr for a 16 hr flight, covering about 8600 nm.

Recent 6,000nm regular scheduled trip on a 777-300ER: TOW 768,400lbs (MAX 769,000) Payload 105,000lbs (including 51,000lbs of cargo) flight time 13h 25m (avg w/f -23kts), fuel burn upon initial cruise alt of FL280 was 16,300lb/h (7.4t/h) Brake release to block-in fuel burn 240,000lbs, avg burn per flight hour 17,900lb/h(8.1t/h)



-widebodyphotog

[Edited 2007-04-09 16:52:20]
 
jetfan727
Posts: 24
Joined: Tue Dec 19, 2006 4:33 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 12:48 am

Quoting PA110 (Reply 111):
Jetfan727 would do well to just take a back seat and listen and learn from the professionals, instead of shooting their mouths off.

You would do well to check it out further before giving this kind of patronizing"advice" I was called a "rookie" precisely by the real kind of rookie you are referring to just because I "dared" say that there was too much unjustified A346 bashing and that many of the A346 operators were not so unhappy with their planes, as some people like to state in this forum. Since you have probably no idea of what my professional activities are and whether they are or not aviation related - and this is not your business anyway - I suggest you would consequently direct your remarks to others. My mistake indeed to have intervened, this place is just not worth it
 
User avatar
zeke
Posts: 16470
Joined: Thu Dec 14, 2006 1:42 pm

RE: Carriers Consider Suing Airbus Over A346 CG Is

Tue Apr 10, 2007 12:57 am

Quoting JetMech (Reply 105):

I know it can be done, but like you I have never had to do it. I think for some strange circumstances like if we had to use JP4 fuel and had a fuel tank temp probe u/s we need to do it, but it is so rare (like JP4 fuel). I cannot see any reason why you could not put fuel in the tail if you needed it, it would automatically get transferred forward just before TOD anyway, the in-flight forward CG is further forward than the takeoff, so that should not be a problem.

Quoting Dougloid (Reply 110):
Now. The horizontal stab on the Airbus has fuel in it like the Md11 did. This is for purposes of trimming the CG in flight to the aft end of the range-it makes for better fuel economy, but it comes at the expense of some stability. That's why they do it.

It does not come at the expense of stability, either the horizontal stabiliser has to be generating a down force to counter the thrust/drag couple, or you put fuel in the tail. By putting fuel in the tail the horizontal stabiliser does not need to generate as much down force, which reduces drag.

Quoting Widebodyphotog (Reply 112):
Payload, zone load, compartment load?

Our loadsheets are done over ACARS, so we don't get a detailed breakdown our payload (not including crew and catering) was about 85klb, we were max fuel for the sector due destination wx and the closest online port (not the closest airport) being used as the alternate to protect the passengers as a schedule disruption management contingency.

Quoting Widebodyphotog (Reply 112):

Recent 6,000nm regular scheduled trip on a 777-300ER: TOW 768,400lbs (MAX 769,000) Payload 105,000lbs (including 51,000lbs of cargo) flight time 13h 25m (avg w/f -23kts), fuel burn upon initial cruise alt of FL280 was 16,300lb/h (7.4t/h)

Your initial cruise fuel [email protected] looks wrong, should be above the average, not below. Fuel flow reduces with the time in fight and at higher flight levels, I would expect about 5% greater than the average, that would make it about 8.5t/hr.

Its costs a lot of fuel at the start of a ULH flight to get that extra 1000+nm that we did, on a shorter trip like the 13h 25 min you described above (maybe DXB-JFK), we could have taken about another 25klb, total payload about 110 klb, and still be 30 klb below MZFW on takeoff. Carried fuel for a diversion from the destination to the closest online port which was about another 20klb due to wx plus normal reserves ontop of that.

BTW : initial cruise alt after taking off at MTOW was FL330, our TOW was about 811 klb.
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 1:17 am

Why the extraordinary hostility to Zeke's statements of actual experience? Fine for WBPG to ask for more data, and I note that W's 6000 nm segment for a 773ER is going to be difficult to compare with the 346's 8600 nm segment, even before trying to allow for the possibly huge differences in wind environments for the two flights.

It is not as if there is a flock of other 346 pilots floating around in the wings with entirely different stories. We learn that the 346 cannot fly the sector described and we also learn that the sector is timetabled. At least nobody has argued with him about the number of engines, just whether it is ETOPs ready.

Anyway, it is good to know that one of our regulars has such influence in design that he can agitate for deletion of something that exists. Wow, that is power.  sarcastic 

I join PA110 in thanking Zeke for his direct insights into actual 346 performance.  Smile

The comments of Dougloid were also interesting both in the extent of received wisdom that might be entirely representative and the use of fuel in the stabs.

As to chip on my shoulder, it is a log actually, and I do apologise if I accidentally struck a raw nerve with said log while bowing, as is my wont at such moments. Must be more careful!  angel 
 
Poitin
Posts: 2651
Joined: Wed Jan 25, 2006 6:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 1:30 am

Quoting Zeke (Reply 114):
It does not come at the expense of stability, either the horizontal stabiliser has to be generating a down force to counter the thrust/drag couple, or you put fuel in the tail. By putting fuel in the tail the horizontal stabiliser does not need to generate as much down force, which reduces drag.

All this is true, Zeke, except your going in argument -- stability is lost. While I have not flown 747s and such I have many hours in a Pitts Special, and I know the further back I move the CG, the less stable the aircraft which also makes it more maneuverable. While I have not gone into competitive aerobatics, several people I know doing it actually load lead shot into the main tube of the vertical stabilizer to fine tune the aft CG.. Those airplanes require a gentle and talented hand to fly, but boy can you fly them.

More fuel in the tail moves the CG aft, deduces required down force, deduces drag, improves fuel economy and reduces stability. Now you could argue, who cares because the autopilot or fly-by-wire system controls that. However, stability, as normally defined as the airplane flying itself straight and level, is less.
 
User avatar
N328KF
Posts: 6028
Joined: Tue May 25, 2004 3:50 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 1:38 am

Quoting Zeke (Reply 100):

The 340 has all the ETOPS equipment of the 330, it has cargo fire protection for 240-280 minutes, which is more than the standard 787 model.

240-280 minutes? My understanding was that the 787 was being engineered for ETOPS-320 equivalent.
 
User avatar
zeke
Posts: 16470
Joined: Thu Dec 14, 2006 1:42 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 2:23 am

Quoting Poitin (Reply 115):
All this is true, Zeke, except your going in argument -- stability is lost.

Maybe it was just my interpretation of the wording. The aircraft remains within the normal CG envelope at all times, it remain 2% forward of the rear boundary, in my view, whilst within the CG envelope there is no "expense of stability", it is still stable, my interpretation of the comments was it becomes unstable.

Quoting N328KF (Reply 116):
My understanding was that the 787 was being engineered for ETOPS-320 equivalent.

What I have seen for the 787 it comes with five extinguisher bottles for the cargo area, two which basically get immediately discharged, and three which are metered that top up the compartment for 180 minutes. Options for the -8 and -9 include an optional additional metered bottle to give 240 minutes, or an optional two additional bottles to give 330 minutes.

The standard 787 will be 180 minutes, the standard 340 is 240 minutes.
 
Dougloid
Posts: 7248
Joined: Tue Jul 05, 2005 2:44 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 2:27 am

Quoting Zeke (Reply 113):
Quoting Dougloid (Reply 110):
Now. The horizontal stab on the Airbus has fuel in it like the Md11 did. This is for purposes of trimming the CG in flight to the aft end of the range-it makes for better fuel economy, but it comes at the expense of some stability. That's why they do it.

It does not come at the expense of stability, either the horizontal stabiliser has to be generating a down force to counter the thrust/drag couple, or you put fuel in the tail. By putting fuel in the tail the horizontal stabiliser does not need to generate as much down force, which reduces drag.

Yes, it does. Flying with the CG in the aft part of the range is inherently less stable than when flying in a nose heavy configuration.
 
User avatar
sunrisevalley
Posts: 5392
Joined: Tue Jul 06, 2004 3:26 am

RE: Carriers Consider Suing Airbus Over A346 CG Is

Tue Apr 10, 2007 2:48 am

Quoting Widebodyphotog (Reply 111):
Recent 6,000nm regular scheduled trip on a 777-300ER: TOW 768,400lbs (MAX 769,000) Payload 105,000lbs


If my methodology is correct and the load/ range charts are close to accurate, this puts the passenger ready weight of this particular aircraft at just under 400000lb. Is that about right?
 
woodsboy
Posts: 900
Joined: Sat Mar 18, 2000 5:59 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:11 am

If operators are going to sue Airbus over the A340-600 CG issues, I wonder why nobody ever sued MD or Boing over the CG charactaristics of the MD80 family? Anybody who has done weight and balance on an MD-8X or 90 knows that when you have a full aircraft with full pits and either at or close to MTOW you have a forward CG that is right at the published limits and as you can imagine (spaghetti with wings) the MD80 has an even longer arm, so it would seem, than the A340-600. With the MD-80s they even give you wiggle room with the forward CG above certain weights where you can go farther forward than the normal limits. I worked with the MD and 737 at Alaska Airlines and routinely had MDs operating at their limits with full loads, no real problems other than perhaps a little more fuel burn on longer sectors. The 737, to its credit was much better balanced but your limits were much closer together, especially at MTOW your didnt have much room to go wrong whereas the MD80 gave you a HUGE limit range at the expense of efficiency!
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:25 am

Quoting Zeke (Reply 113):
Your initial cruise fuel [email protected] looks wrong, should be above the average, not below. Fuel flow reduces with the time in fight and at higher flight levels, I would expect about 5% greater than the average, that would make it about 8.5t/hr.

Don't see why that would be as from takeoff to ICA the fuel flow rates are much higher than they are at cruise. The avg I detailed is from takeoff to block-in including all segments in between. Simply total fuel burned divided by total time in the air. That should be higher than any cruise altitude specific figure because of the higher fuel flows in the first portion of the flight are included. For that particular flight flow rate for the climb up to FL280 avg 9.4t/h. The flight landed with 13t of fuel on board. This was a Westbound trip...

By the altitudes FL280 7.4t/h FL300 7.0t/h and FL300 was at that altitude for a looong time, then 6.3t/h at FL320.

Quoting Zeke (Reply 113):
Its costs a lot of fuel at the start of a ULH flight to get that extra 1000+nm that we did, on a shorter trip like the 13h 25 min you described above (maybe DXB-JFK), we could have taken about another 25klb, total payload about 110 klb, and still be 30 klb below MZFW on takeoff. Carried fuel for a diversion from the destination to the closest online port which was about another 20klb due to wx plus normal reserves ontop of that.

Most of the trips we make East or Westbound are at a high percentage of MTOW because the total payloads are so high. Generally in the area of 100-125,000lbs. With so much load in the belly CG problems are non-existant. Fuel policy is lean because the online stations are very close to the planned destinations on either side of the Pacific and we don't need much extra to be comfortable. The biggest hit we'll take in fuel will be 7-9t additional for weather/long divert and that is usually on the Westbound trip.

Quoting Baroque (Reply 114):
Why the extraordinary hostility to Zeke's statements of actual experience? Fine for WBPG to ask for more data, and I note that W's 6000 nm segment for a 773ER is going to be difficult to compare with the 346's 8600 nm segment, even before trying to allow for the possibly huge differences in wind environments for the two flights.

Not really. MTOW is MTOW and both airplanes are at or near that. At departure from MTOW initial cruise altitudes and fuel flows will be the same irrespective of distance flown. The only difference is the mass fraction of fuel on board and time points at which ascents to higher altitudes occur if any. At the end of the flight the airplane with the higher mass fraction of fuel would burn relatively less as it's ZFW is lower so the overall average burn (all segments included) would be less. And let's be clear it was 8,600nm with an 80kt tail wind and 6,000nm with a 23kt headwind. In terms of what the airplane "sees" it's more like a 7,500nm flight (or less) for the Airbus and a 6,300nm flight for the Boeing. Not really a huge difference when considering airplanes at MTOW.

Wind costs or subtracts time in the air for which you add and subtract fuel. When at MTOW additional fuel comes out of the payload which is reduced and when the fuel requirement is reduced payload can be added. At MTOW and given a similar set of atmospheric conditions I'm going to burn the same amount of fuel to get to initial cruise altitude for a 6,000nm flight as a 4,000nm flight. The difference is going to be after that where the airplane on the shorter range mission is going to be heavier for a given weight of fuel and will burn it's fuel over a shorter amount of time than the longer ranged airplane that will end it's cruise lighter and burning fuel at a lower rate.

So if we are to in some way equalize our two examples the 777-300ER would reduce payload, add fuel and the rate of fuel burn becomes lower when averaged over a longer flight while the A340-600 would increase payload and increase the overall rate of fuel burn over a shorter flight.



-widebodyphotog
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:37 am

Quoting SunriseValley (Reply 119):
If my methodology is correct and the load/ range charts are close to accurate, this puts the passenger ready weight of this particular aircraft at just under 400000lb. Is that about right?

More than 5t less than that is all I'll say...



-widebodyphotog
 
SailorOrion
Posts: 1960
Joined: Tue Feb 06, 2001 5:56 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:37 am

Sorry but the fuel burn figures I gave are official LH data. From the preliminary data they have it appears they assume both the 748 and the 388 to be about 10-12% better than the current best model (A343)

SailorOrion
 
ikramerica
Posts: 15188
Joined: Mon May 23, 2005 9:33 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:40 am

Quoting Baroque (Reply 114):
Why the extraordinary hostility to Zeke's statements of actual experience? Fine for WBPG to ask for more data, and I note that W's 6000 nm segment for a 773ER is going to be difficult to compare with the 346's 8600 nm segment, even before trying to allow for the possibly huge differences in wind environments for the two flights.

What 8600nm segment? What plane are we talking about here?

And notice how Zeke and WBP both are not in complete agreement, despite both of them doing this for a living.

I've lived long enough to know that even people who do things day in and day out are not 100% right, 100% experts, 100% without bias.

It's a fool who believes everything he reads or sees just because he has less knowledge of the subject. The sage takes in the information, processes, tries to find out more, and then assesses it. And certain people here try to leverage their jobs/experience to force opinion down our throats as fact.

I am not saying Zeke does that, but there are people who do it.

But i do find that Zeke's experiences don't always jive with the greater market as a whole. Maybe his airline does things differently...
 
widebodyphotog
Posts: 885
Joined: Wed Jun 30, 1999 9:23 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 3:59 am

Quoting Zeke (Reply 117):
Maybe it was just my interpretation of the wording. The aircraft remains within the normal CG envelope at all times, it remain 2% forward of the rear boundary, in my view, whilst within the CG envelope there is no "expense of stability", it is still stable, my interpretation of the comments was it becomes unstable

Agreed, however I believe what the complaint is centers arround what the carriers must do to stay within limits which is reduce load in the forward hold. I don't believe this is a crisis of safety but of operators wanting to maximize revenues and not being able to without comprimising safety.

Quoting Ikramerica (Reply 124):
But i do find that Zeke's experiences don't always jive with the greater market as a whole. Maybe his airline does things differently...

He's got very learned and informed opinions and from what I know about CX their operation is very squared away. Yes other carriers operate differently in some respects but that's not a knock against CX.



-widebodyphotog
 
mham001
Posts: 5745
Joined: Thu Feb 03, 2005 4:52 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 4:10 am

I am not in any way qualified to question a professional, but I would not be so quick to jump on the bandwagon that every professional here pulls. I have seen over the years statements made, such as "everything Boeing makes is garbage" by a known professional(and then attempt to defend the statement). I have seen said professional had his a** handed to him by an equally qualified professional in a debate about the intricacies of their trade similar to this discussion, to the point where I had serious thoughts about not wanting to fly with certain people at the controls. Bottom line, don't take everything you read here as gospel, no matter the qualifications.
 
OldAeroGuy
Posts: 3928
Joined: Sun Dec 05, 2004 6:50 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 4:15 am

Quoting Zeke (Reply 117):
The standard 787 will be 180 minutes, the standard 340 is 240 minutes.

But 180 min. works well for most operators and routes, with no routing changes required to remain within 180 min operating distances. If more diversion time is required, the 787 will be capable of diversion times in excess of 240 min by adding additional fire suppression bottles.

If you don't need the additional capability, the standard 180 ETOPS fit avoids the operational penalty of carrying the additional fire suppression weight.
 
Dougloid
Posts: 7248
Joined: Tue Jul 05, 2005 2:44 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 4:17 am

Quoting Woodsboy (Reply 120):
If operators are going to sue Airbus over the A340-600 CG issues, I wonder why nobody ever sued MD or Boing over the CG charactaristics of the MD80 family?

Because the whiners and professional victims have taken over the airlines, or at least the ones that operate this class of aircraft and pretend to be surprised that this sort of result happened.

It reminds me of some of the dialogue Casablanca:

Rick: I came here for the waters
Louie: Casablanca is in the middle of a desert
Rick: I was misinformed.

Louie: I'm shocked that gambling is going on in this establishment!

Louie: Major Strasser has been shot. Round up the usual suspects!
 
Poitin
Posts: 2651
Joined: Wed Jan 25, 2006 6:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Is

Tue Apr 10, 2007 4:30 am

Quoting Zeke (Reply 117):
Quoting Poitin (Reply 115):
All this is true, Zeke, except your going in argument -- stability is lost.

Maybe it was just my interpretation of the wording. The aircraft remains within the normal CG envelope at all times, it remain 2% forward of the rear boundary, in my view, whilst within the CG envelope there is no "expense of stability", it is still stable, my interpretation of the comments was it becomes unstable.



Quoting Dougloid (Reply 118):
Yes, it does. Flying with the CG in the aft part of the range is inherently less stable than when flying in a nose heavy configuration.

Dougloid is correct.

Perhaps it is semantics, Zeke, but when I learned to fly many many years ago, I was permitted to only fly "stable" aircraft which would, if put into a spin, would recover with the "Jesus Christ" maneuver -- i.e. hands and feet off the controls. My C-175 was such an aircraft -- you had to keep it in a spin. More than once I manhandled it into a spin and it would recover all by itself in two or three turns if I took my hands and feet off the controls. Stability is the natural tendency of a aircraft to return to straight and level flight if left to its on devices and assuming proper trim and CG. Most general aviation aircraft are stable, and this has led to the stupid removal of the spin training requirements for the private pilot license many years ago. While such aircraft will recover, the pilot can still keep it in a spin by simply pulling back on the yoke or stick. Every year pilots spin their aircraft into the ground with the wheel pulled tight into their gut as they screamed in panic all the way down.

I have also flown a Pitts which is "sorta" unstable. If put into a spin, it would stay there until you flew out of it. On the other hand you did not have to hand-fly it all the time. It would continue to straight and level if I took my hands off the controls while fly that way.

I have also flown competition aerobatic Pitts which had their CG moved way back to the back-most "legal" CG and those were airplanes you had to fly all the time. However, they were much more maneuverable that the Pitts I normally flew, which had it CG in the mid-point of its range. The only difference was the location of the CG as compared to the one I normally flew.

Modern military aircraft such as the F16, F22, B-2 and such are completely unstable aircraft. If the fly-by-wire system failed, it would spin out of control in an few seconds.

There are two issues here. One is the A346 "less stable" if the CG is moved back? Clearly it is. The second and more important issue is does it matter? I would serious doubt it would as long as the CG is within specifications and the pilot doesn't do stupid things. In short, it probably wouldn't matter one little bit as the aircraft would fly normally and the fly-by-wire system would make any shaking of the back end disappear. I would have no problem flying or flying in an aircraft which had it's CG moved back, as long as it would be in limits. I suspect this is what you are really trying to say, and I would agree with that.
 
User avatar
SEPilot
Posts: 5753
Joined: Sat Dec 30, 2006 10:21 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 4:35 am

Quoting Dougloid (Reply 128):
Because the whiners and professional victims have taken over the airlines, or at least the ones that operate this class of aircraft and pretend to be surprised that this sort of result happened.

As mentioned earlier, if Airbus gave incorrect data at any stage of the process they are liable to be sued. If Boeing and/or MD said this is what you have, live with it, there are no grounds for a suit.
 
RoyalAtlantis
Posts: 102
Joined: Tue Nov 21, 2006 6:02 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 4:49 am

Quoting Zeke (Reply 85):
Somehow I dont think you have flown on a 345/346.

i see your respect ratings and read your posts...but watch your words - I have flown on CX from JFK-HKG...and AC from YYZ-HKG - so who are you to make the statement "somehow i don't you have flown on a 345/A346?" My experience is mine and this forum is for people to express their knowledge and experience. I'm hoping you're not crew on any of my CX flights because your editorial comments are crap pal. Keep them to yourself when qualifying statements or adding facts/opinions.
 
User avatar
zeke
Posts: 16470
Joined: Thu Dec 14, 2006 1:42 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 5:58 am

Quoting Ikramerica (Reply 124):
What 8600nm segment? What plane are we talking about here?

346 doing HKG-JFK along a route like HKG-TPE-30N 160E-33N 179E-35N 160W-36N 140W-KJFK following the winds.

Quoting RoyalAtlantis (Reply 131):
Keep them to yourself when qualifying statements or adding facts/opinions.

Sorry if that sounded condescending. What you said is completely the opposite of what our crews have said to me, which prompted my comments.

As you would know the rear galley is several meters behind the last rows of seats, and the crew rest is under the rear seats/rear toilets, as they fly 100-150 hours a month on a variety of aircraft, and many have been doing so for over 10 years, I tend to take their observations of sights, smells, and movements as being reliable, many of them have more flying experience than me. I have never flown on a Convair 880, but some of the people I hear from have been around long enough to have worked on them as crew.

When going through clear air turbulence, following a jetstream going across the pacific, the mountain waves over northern China etc, the 346 rides well. What I said is factually correct, no other civil aircraft I know has a structural damping mode specifically added to make the passenger ride smoother, particularly in the rear of an aircraft.
 
Poitin
Posts: 2651
Joined: Wed Jan 25, 2006 6:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 6:22 am

Quoting Zeke (Reply 132):
What I said is factually correct, no other civil aircraft I know has a structural damping mode specifically added to make the passenger ride smoother, particularly in the rear of an aircraft.

I am not sure what you mean by "structural damping mode". Are you referring to the FBW dampening I would expect the electronics to give automatically, or is there some new gizmo on the 340?

And why would not the A320 and A330 have the same dampening?
 
User avatar
zeke
Posts: 16470
Joined: Thu Dec 14, 2006 1:42 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 7:09 am

Quoting Poitin (Reply 133):
I am not sure what you mean by "structural damping mode". Are you referring to the FBW dampening I would expect the electronics to give automatically, or is there some new gizmo on the 340?

From one of the 340 differences documents :

"The flight control laws have been redesigned on the A340-500/600 to damp out structural oscillations and to improve turbulence damping. This has been, in part, helped by a change to the flight control system architecture, such that the autopilot inner loop computations are now carried out by the Primary Flight Control Computers (PRIMs), rather than the Flight Management and Guidance Computers (FMGCs). Previously, the IRSs were used as sensors for the handling functions and separate accelerometers used for comfort functions. Now all sensors, including some additional gyrometers, will be used for both handling and comfort functions."

The 345/346 also has over 10% greater wing loading than the 343 which makes the gust response better as well.
 
Dougloid
Posts: 7248
Joined: Tue Jul 05, 2005 2:44 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 10:00 am

Quoting Zeke (Reply 134):
Quoting Poitin (Reply 133):
I am not sure what you mean by "structural damping mode". Are you referring to the FBW dampening I would expect the electronics to give automatically, or is there some new gizmo on the 340?

From one of the 340 differences documents :

"The flight control laws have been redesigned on the A340-500/600 to damp out structural oscillations and to improve turbulence damping. This has been, in part, helped by a change to the flight control system architecture, such that the autopilot inner loop computations are now carried out by the Primary Flight Control Computers (PRIMs), rather than the Flight Management and Guidance Computers (FMGCs). Previously, the IRSs were used as sensors for the handling functions and separate accelerometers used for comfort functions. Now all sensors, including some additional gyrometers, will be used for both handling and comfort functions."

I had not heard about this but it stands to reason that small FMS directed control movements could do a lot toward ensuring a more comfortable ride by compensating for buffeting and suchlike.
 
User avatar
jetmech
Posts: 2391
Joined: Wed Mar 29, 2006 2:14 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 1:56 pm

Quoting Dougloid (Reply 135):

G'day Dougloid  Smile,

I think the concept had quite an early inception with aircraft. The Bristol Brabazon from the 1940's had a gust alleviation system to reduce turbulence induced bending loads upon it's wings, which had a span of 70m.

http://www.unrealaircraft.com/classics/brab.php

http://rpec.co.uk/engineerswalk/pics/Brabazon.jpg

http://rpec.co.uk/engineerswalk/pics/Brabazon.jpg

Regards, JetMech
 
baroque
Posts: 12302
Joined: Thu Apr 27, 2006 2:15 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 7:33 pm

Quoting Widebodyphotog (Reply 121):
And let's be clear it was 8,600nm with an 80kt tail wind and 6,000nm with a 23kt headwind. In terms of what the airplane "sees" it's more like a 7,500nm flight (or less) for the Airbus and a 6,300nm flight for the Boeing. Not really a huge difference when considering airplanes at MTOW.

I had a feeling there must have been an overall difference in headwinds. That would have to be taken into account, probably segment by segment if changes were made to the air speeds as a result. It is going to be very difficult to get a like against like comparison. A start would be flying the same mission, preferably with the same winds, but even then, they ARE different planes. Even on those revised numbers you would have to find a way to "credit" the 346 with carting the extra fuel for the extra 800nm.

As Zeke explains, the 346s have some fancy methods of making their stability better in terms of the pax. Obviously, there is one unhappy pax, but perhaps many happy pax. I hope to fly CX later this year, we shall see.

Quoting Dougloid (Reply 128):
It reminds me of some of the dialogue Casablanca:

Rick: I came here for the waters
Louie: Casablanca is in the middle of a desert
Rick: I was misinformed.

Or alternatively of the English lady who cabled back to Cooks travel agents on arriving in Venice as follows:
"Roads flooded, please advise".
 
PolymerPlane
Posts: 832
Joined: Thu May 11, 2006 1:12 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 8:21 pm

Quoting Baroque (Reply 137):
Even on those revised numbers you would have to find a way to "credit" the 346 with carting the extra fuel for the extra 800nm.

No, because the 773ER took off near MTOW. That means the plane carried as much weight as it would have if it were doing the same mission as the A346. The overall average fuel burn per hour should have been lower if the 773ER were to do longer mission, since towards the end of the mission the aircraft is much lighter. One kg is still one kg regardless whether it is fuel or payload.

Quoting Baroque (Reply 137):
A start would be flying the same mission, preferably with the same winds, but even then, they ARE different planes.

That's right, they are different plane, thus different efficiency. From rough numbers Zeke and WBP provided the difference is about 10% or more.

Cheers,
PP
 
Flying-Tiger
Posts: 4152
Joined: Mon Aug 23, 1999 5:35 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 8:27 pm

Have heard that Boeing is running into similar problems with the 787 at the moment as well (too heavy F/C-seats), and had to strengthen the floor to be able to have the seats safely installed. Currently the airlines seem to take up every available kg to install even fancier equipment by the day... all comes at a hefty weight penalty.
 
Poitin
Posts: 2651
Joined: Wed Jan 25, 2006 6:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Tue Apr 10, 2007 11:09 pm

Quoting Zeke (Reply 134):
"The flight control laws have been redesigned on the A340-500/600 to damp out structural oscillations and to improve turbulence damping. This has been, in part, helped by a change to the flight control system architecture, such that the autopilot inner loop computations are now carried out by the Primary Flight Control Computers (PRIMs), rather than the Flight Management and Guidance Computers (FMGCs). Previously, the IRSs were used as sensors for the handling functions and separate accelerometers used for comfort functions. Now all sensors, including some additional gyrometers, will be used for both handling and comfort functions."

So it is the FBW system being used in a clever way. Obviously, they added some sensors to detect the turbulence and oscillations, but there is no rocket science here, just smart engineering. I am surprised that they haven't added it to the A320 and A330. I am sure they have it on the A380.

Thank you for explaining.

Quoting JetMech (Reply 136):
I think the concept had quite an early inception with aircraft. The Bristol Brabazon from the 1940's had a gust alleviation system to reduce turbulence induced bending loads upon it's wings, which had a span of 70m.

While the Brabazon had a gust unloading system, it was fairly primitive, and there are quite a few aircraft with such systems installed today. The A346 is either a three axis system, or should be and it completely digital. I would expect the A 380 to have it as well. Heck, you have a FBW system, you might as well use it.
 
Rheinbote
Posts: 1103
Joined: Sun May 21, 2006 9:30 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 3:30 am

Quoting Poitin (Reply 133):
I am not sure what you mean by "structural damping mode". Are you referring to the FBW dampening I would expect the electronics to give automatically, or is there some new gizmo on the 340?

And why would not the A320 and A330 have the same dampening?



Quoting Poitin (Reply 140):
So it is the FBW system being used in a clever way. Obviously, they added some sensors to detect the turbulence and oscillations, but there is no rocket science here, just smart engineering. I am surprised that they haven't added it to the A320 and A330. I am sure they have it on the A380.

What Zeke described (with more detail than I know) is a structural mode control system that may be integrated into an FBW system, but is not necessarily an inherent function of an FBW system. In the A340-600, there are no sensors to detect the turturbulence, just accelerometers which sense the oscillation of the structure as induced by gust(s). These oscillations are dampened using the flight control surfaces already available (the B-1 bomber employs nose vanes). In case of the A340-600 the yaw damper is used to cancel out lateral oscillations of the forward fuselage which originated from an oscillation of the outboard engine/pylon combo IIRC.

The A320 and A330 don not have such a dampening system simply because they don't need one.

I'm not completely sure, but I think the 777-300ER is using a similar system to address the famous 'fish-tailing' problem which should be self-explanatory.
 
aminobwana
Posts: 923
Joined: Tue Apr 10, 2007 7:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 4:01 am

Lets keep this simple:


1) In the specs Airbus must have indicated which is the max. load forward permisible for
max, range flights. It is hardly believable that if let's say the aft economy section is
half empty, the premier class cannot be fully occupied only to maintain the CG in its range

2) It is also hardly believable that airlines have not consulted with Airbus the distribution
of weight in 1st/B class, as the momentum or arm must be considered. And of course.
this is more pertinent if AIRBUS itseld made the installation

3) If the 406 is compared with the 403,
it can be seen that that the additional lenght of 10 m was distributed 6.50m in front and
3.50m after the wing. This obviously, relatively speaking, shifted the CG forward.

4) I would assume thet that the CG is situated in front of the center of the wing.
Therefore, when the specs were changed by reducing the weight of the wing, the
CG was shifted forward again.

5) It is misleading to insist only on the weight of the 1st class (12 seats).
Much more important is the B-Class (54), where the difference compared
with E-class is by far lower, and as there are 6 B-seats in the same area as
12.5 E-seats, the difference should be not a big deal

6) The declaration of AIRBUS/ Mr. Leahy are again, as in the case of the
A380. not credible where he compares the 555 seat A380 with the discontinued
417 seat B747-400 , touting the 35% difference when the reality is 19%
compared with the competing 467 seat B747- 8 -I, telling that the fuel
consumption per seat is much better (true with the 400, but false with the 8-I) etc.
Another example: he compares the A350XWB -800 with the
much smaller B787-8, instead with the comparable B787-900.

7) Why the Airlines have not said nothing publicly for up to 4 1/2 years ??
Primarely, because several of them as LH, AF and IB are precisely in the
countries where the A340 is build, and also becuse Mr. Leahy promised
them to fix the problem. As he did not, now some of them are furious !!

8) And has AIRBUS asked the certifying agencies to amend the original
certification, after the wing design change and the 5 Ton "advise" ???
If airlines were flying a potentially unstable aircraft for years under such
conditions, this would become an extremely serious matter !!

aminobwana
 
Dougloid
Posts: 7248
Joined: Tue Jul 05, 2005 2:44 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 5:23 am

Quoting Aminobwana (Reply 142):
1) In the specs Airbus must have indicated which is the max. load forward permisible for
max, range flights. It is hardly believable that if let's say the aft economy section is
half empty, the premier class cannot be fully occupied only to maintain the CG in its range

If aft economy section is half empty that moves the CG forward yet more.

Quoting Aminobwana (Reply 142):
2) It is also hardly believable that airlines have not consulted with Airbus the distribution
of weight in 1st/B class, as the momentum or arm must be considered. And of course.
this is more pertinent if AIRBUS itseld made the installation

What I said.

Quoting Aminobwana (Reply 142):
4) I would assume thet that the CG is situated in front of the center of the wing.
Therefore, when the specs were changed by reducing the weight of the wing, the
CG was shifted forward again.

It's probably described in per cent MAC (mean aerodynamic chord)

Quoting Aminobwana (Reply 142):
5) It is misleading to insist only on the weight of the 1st class (12 seats).
Much more important is the B-Class (54), where the difference compared
with E-class is by far lower, and as there are 6 B-seats in the same area as
12.5 E-seats, the difference should be not a big deal

Depends on the weight of the cabin furnishings and their arm.

Quoting Aminobwana (Reply 142):
3) If the 406 is compared with the 403,
it can be seen that that the additional lenght of 10 m was distributed 6.50m in front and
3.50m after the wing. This obviously, relatively speaking, shifted the CG forward.

Assuming the CG range was not adjusted. Different versions of the same aircraft may have different CG envelopes.

Quoting Aminobwana (Reply 142):
Lets keep this simple:

I agree. If Airbus did the installation, then they're at least partly to blame. If the airlines did this retrofit after taking delivery, then they're the ones with the problem and they have seen the enemy, and he is us so to speak.
 
aminobwana
Posts: 923
Joined: Tue Apr 10, 2007 7:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 11:28 pm

quoting DOUGLOID reply 143 April 10

to 1) You write: :If aft economy section is half empty that moves the CG forward yet more.

This is my point ! Even if this seems clearly absurd, in such case if the CG shall remain in its range, they must reduce the premium class occupancy !!!

to 4) you write:: It's probably described in per cent MAC (mean aerodynamic chord)

I am no specialist and do not understand your comment. Bear with me ! My question is: do you think that the
CG is in front of the wing, therefore if the weight of the latter became less after the initial certification, , the CG was shifted forward

to 3) you write:: Assuming the CG range was not adjusted. Different versions of the same aircraft may have different CG envelopes

Agreed: But as in my opinion AIRBUS somewhere made a mistake,, it could be precisely here.

to 2) you write:: I agree. If Airbus did the installation, then they're at least partly to blame. If the airlines did this . retrofit after taking delivery, then they're the ones with the problem and they have seen the enemy, and he is us so to speak

Please let me know your qualified opinion regarding if it is compatible with regulations that airlines can make such retrofits without approval of the manufacturer ?? In my opinion, this would be outrageous, as many airlines have not the
technical qualifications to assess the consequences !!

And must not all this information be posted to the certifying agencies before they issue the certification and if there is
a modification afterwards, the certification itself must be ammended ??
If not so, what sense makes the certification at all, if, as it seems happened here, the frontal overweight problem was
noted after 4 years ! Thisis really difficult to believe !

I THINK HERE IS THE CRUX OF THE ISSUE !!!
 
SailorOrion
Posts: 1960
Joined: Tue Feb 06, 2001 5:56 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 11:49 pm

The certification agencies care crap whether your aircraft is overweight or whether the installed (and certified) seats move the CG front. As long as the CG is in the allowed range, it is fine with them...

SailorOrion
 
coa747
Posts: 380
Joined: Wed Jul 13, 2005 3:11 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Wed Apr 11, 2007 11:56 pm

Yeah because Airbus has never stretched the truth, like when they told Cathay that the A340-600 could make New York nonstop, but were careful not to say City. Buffalo or Syracuse yes but not New York City. Same song and dance from Airbus. Fact is I don't think they were totally honest with their customers. Especially now they are desperate to sell the A340 to anyone. Boeing has exceeded customer expectations with the 777 and hasn't left the airlines to discover any nasty surprises. When you sell someone a 200 million dollar airplane they have certain expectations. When you have a problem with it and the manufacture just turns around and says tough deal with it. You aren't likely as an airline to take that very well, and it is likely to be fresh in your mind the next time you consider ordering a product from them.
 
pilot21
Posts: 985
Joined: Sun Oct 24, 1999 8:28 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Thu Apr 12, 2007 12:35 am

Quoting Coa747 (Reply 146):
Yeah because Airbus has never stretched the truth, like when they told Cathay that the A340-600 could make New York nonstop, but were careful not to say City. Buffalo or Syracuse yes but not New York City.

But it can make HKG-JFK nonstop, and does so on a daily basis! A fine ride I had it in too in 2005 flying between those two great Cities!
 
trex8
Posts: 5721
Joined: Sat Nov 02, 2002 9:04 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Thu Apr 12, 2007 1:39 am

Airbus was overweight on the wings with the first few production A346s , which CX got, even then it has not stopped CX flying that route regularly non stop westbound. Might they be making more money on that route than they could be, sure, probably why they are getting 77Ws, but the A346 is clearly running JFK-HKG with heavy loads regularly without problems. I flew that last summer, the plane was almost totally full in Y , few empty seats here and there only, and J was almost completely full as far as I could tell also. My one and only A346 experience. can't say it was particularly memorable in terms of the plane itself compared to any other plane (I'm usually in a UA 777 or 747 and usually E+ so its apples and oranges comparing the seats) though the food was clearly better!
 
aminobwana
Posts: 923
Joined: Tue Apr 10, 2007 7:32 am

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Mon Apr 16, 2007 8:22 am

Quoting Atmx2000 (Thread starter):
SailorOrion From Germany, joined Feb 2001, 1652 posts, RR: 3
Reply 143, posted Wed Apr 11 2007 08:49:55 your local time (4 days 8 hours ago) and read 795 times:


The certification agencies care crap whether your aircraft is overweight or whether the installed
(and certified) seats move the CG front. As long as the CG is in the allowed range, it is fine with them...

----------------------------------------------------------------
My question was:
Please let me know your qualified opinion regarding if it is compatible with regulations that airlines can
make such retrofits without approval of the manufacturer ?? In my opinion, this would be outrageous,
as many airlines have not thetechnical qualifications to assess the consequences !!

And must not all this information be posted to the certifying agencies before they issue the certification
and if there is a modification afterwards, the certification itself must be amended ??
If not so, what sense makes the certification at all, if, as it seems happened here, the frontal overweight
problem was noted after 4 years ! This is really difficult to believe
---------------------------------------------- ------------------

So I have now some questions:

1) If a company which otherwise is reliable and a good, but not technically knowledgeable,
calculates the CG position wrongly, then eventually the plane crashes, then the certification agency
(and the manufacturer) can wash their hands ?? I did not know that Pontius Pilatus headed such a
n Agency

2) I again ask: is it permissible that airlines retrofit substantially the cabins without informing and
consulting with the manufacturer

3) I understand that in the majority of cases, the customer tells the manufacturer what he wants
and eventually purchases himself the goods, but the first installation is made by the manufacturer.
Does he so without verifying ??

4) How it is then possible that 4 years after commercial op, Airbus suddenly tells the the Airlines
to shed 5 Tons (!) from the front part ?? If as you say this is responsibility of the Airlines
(all or several of them ??) is this not the best proof that such decision cannot be left to them ??

I5) Must, I repeat, any of such happening be reported and acknowledged by the certification
agencies ??

I would appreciate that somebody gives me a concrete and concise answer to these questions T
hese are not questions of opinion, but information regarding rules.

Thanks in advance

aminobwana
 
starguy
Posts: 260
Joined: Sat Dec 17, 2005 10:44 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Thu Apr 19, 2007 8:15 pm

The Daily Mirror has reported that Virgin Atlantic are unhappy with their A346 because the weight of the nose section has resulted in the amount of cargo carried on flights being reduced.

http://www.mirror.co.uk/news/topstor...6312%26siteid=89520-name_page.html
 
astuteman
Posts: 7466
Joined: Mon Jan 24, 2005 7:50 pm

RE: Carriers Consider Suing Airbus Over A346 CG Issues

Thu Apr 19, 2007 9:17 pm

Quoting Poitin (Reply 113):
More fuel in the tail moves the CG aft, deduces required down force, deduces drag, improves fuel economy and reduces stability

Coming late to the (fascinating) thread......
But isn't the point here to put more fuel in the tail in order to correct a C of G that is overly forward?
And result in a C of G that is further within the allowed parameters, permitting greater loading flexibility?

Quoting Dougloid (Reply 116):
Yes, it does. Flying with the CG in the aft part of the range is inherently less stable than when flying in a nose heavy configuration.

Ditto........

Regards

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos