A380 MLG Tire Scuffing/Skidding

[Halfnut]

I received this last night. Anyone know what is going on here and please don't shoot the messenger!

Sorry but you'll have to click on the links below to see the photos that came with the email message.

=================

For those of you who aren't passingly familiar with what this is all about ... someone was trying to turn AirBus' great big, brand-new, A380 aircraft a little too sharply (we don't know whether under it's own power, or while it was under tow).

AirBus elected NOT to make their main landing gear system (four separate gear with four wheels apiece) steerable. Why? You save a considerable amount of weight -- not to mention some serious extra cost -- by not doing so. There is a trade-off, however ...

When you have non-steerable gear that are configured like they are on this aircraft, you have scuffing/skidding going on whenever you turn the aircraft. This isn't an unusual design for a wheeled vehicle, though. For instance, a dual-axle semi-trailer does the same thing when it's being maneuvered sharply within a warehouse parking lit. What makes the A380 so special, is the incredible amount of weight on each huge tire, in conjunction with the widely-spaced gear. In concert, these two aspects considerably magnify the inherent problem -- to the point where the asphalt (not just the rubber tire) is taking it in the shorts ... not to mention the stress and overload that's happening to the entire structure between the tire and the gear attaching points in the wing structure. Note the apparent bending of the gear in one of the shots! No, Mildred, that is NOT a good thing to be happening to your aircraft's main landing gear. Unless they're making everything out of rubber, those stress loads have GOT to be off the scale!

As new-aircraft design problems go, this will likely prove to be a very expensive one for AirBus to deal with. It's either that, or the aircraft will only be able to operate in and out of airports that have the extra fifty-acres it will need to get safely turned-around. It'll be interesting to see how they solve this one.

http://img308.imageshack.us/my.php?image=tire33bn.jpg

http://img341.imageshack.us/my.php?image=tire11cc.jpg

http://img341.imageshack.us/my.php?image=tire24vn.jpg

[Leftit2L8]

Dramatic piccies. Might go some way to explain the recently announced 6 month delay ? Maybe it was some kind of test ?

[Seloco]

If those pictures are real then I cannot believe that this damage was caused simply by lateral scuffing in a turn. It looks much more like the results of a high-speed skid on landing; those wheels have gone almost 90 degrees sideways, for goodness sake!

[bzh]

it's ok they have michelin tire...:} :}

[TyroPicard]

You wouldn't want to find that on the walkround!

Looks to me like a pushback - those are the wing gear (4 wheels). The 747 wing gear do not turn either - it's the body gear that turns. Perhaps the weight penalty and complexity is too great for wing gear to swivel?

Skid angle looks about 60 deg... hope they scrapped the tyres....

Cheers, TP

[A4]

I agree with Seloco. I don't believe they are the result of a normal turn / pushback. It's even gouged the tarmac!

Mind you, on a second look if the tug had got to 90° for a "tight" push , then it's not inconcievable that the bogey on the inside of the turn would scuff. That is what it looks like on the first picture which appear to show the inner (turn) bogey pictured from the front.

I hope someone hasn't made a monumental 8all5 up at the design stage.

A4 :uhoh:

Edited after second look at pics.

[BOAC]

C'est un tour de frein à main, n'est-ce-pas?:D

[Bmused55]

One rather large problem for Airbus if this is as originaly decribed.

Making the gear steerable at the back would seems to be a must and plain common sense on an aicraft this size. But, you can bet they did not make them steerable to save weight, considering the thing is overweight as it is.

Have they perhaps shot themselves in the foot on this one? and if this is not connected to the recent announcement about the delaying of deliveries for 6 months... how much longer do you think it will delay the aircraft? And how much longer are the customers going to wait?

[African Tech Rep]

Put Bridgestone on it - they corner better but do take a while to get to temp ;)

[unwiseowl]

Assuming, of course, that these are genuine pictures...................?????????

[Bmused55]

Assuming, of course, that these are genuine pictures...................?????????

If they are not, then what are they?

They depict the outer gear of the a380 scuffed and buckled.
IMO, these are genuine photos... the quality is just too good for fakes.

But, if they are fakes, then of what aircraft are they?

I know of no other aircraft with 6 wheel bogies under the fuselage and 4 wheel bogies under the wing.

[vanhigher]

please please don't let 747 Focal see this, we'll never hear the end ...:bored:

[Jando]

The pictures might well be genuine - perhaps from a test?

However, the story of the original poster is certainly not genuine, just too many factual errors in it.

AirBus elected NOT to make their main landing gear system (four separate gear with four wheels apiece) steerable.

Four gears with four wheels? If I'm not completely blind then I count 6 six wheels under the body gear. Not steerable? As far as I know the body landing gear is steerable, it's the 4-wheeled wing gears that aren't. But then I'm no aircraft engineer and when someone thinks that Airbus and Goodrich (they're actually building the gears) got it all wrong ...

[BahrainLad]

What makes the A380 so special, is the incredible amount of weight on each huge tire

Special? Pavement loading from each wheel is similar to the 747-400 and below that of the 777-300ER.

I'm sure the photos are of a test. Remember when they landed a A340-600 at over MTOW? Almost destroyed the MLG....but the a/c survived.

[Spitoon]

Well I'm keen to hear the full story - I've got a similar problem on my car!

[Flip Flop Flyer]

Have a word with your push-back driver mate; coffe sans biccies!

[Bmused55]

Well I'm keen to hear the full story - I've got a similar problem on my car!

Perhaps reducing your speed round those corners could help. :ok: :E

[Trash Hauler]

I would venture (based on the fact the aircraft is in a testing phase) that this is a test. Whether it passed or not depends on what the parameters were. For my money it passed. The tyres are still on the rims, none appear to be deflated and despite the tear on the tarmac it is relatively minor for the weight of the aircraft.

[canadair]

Perhaps this is just the results from the test of Lufthansa`s standard taxi speeds?:D

[Farrell]

Canadair.....

It was actually a test performed by Ryanair......but it couldn't cope with the turnaround!

[Flight Detent]

This post should be in the Tech Log section !

Same subject brought up on the 13JUL under

"Airbus A380 Undercarriage System"

I didn't show the photos

FD :uhoh:

[RRAAMJET]

I'm wondering what the fuel loading situation was - perhaps heavy wing load and light centre tank loads - combined with hot ambient temps? But the tires buckling like that should not happen. I know of no test on the -400 that produced that effect on wing tires.

Trash Hauler - I disagree. This is not a pass of a normal test that I am aware of. I've spot turned the -400 & 777, and been under tow in tight turns at max weight (which produces a tighter steering angle) and I have never seen the tires peel off the rims. If the piccies are genuine, I'm sure Airbus have some head scratching to do. It is possible this was meant to simulate some ham-fist cranking the steering over to max at too high a ground speed, but even so....you'd expect the nose gear to give up traction first and slide.

I'm very curious, and still envious of those that get to fly this aircraft.

[SMOC]

The rear axle of the body gear is steerable like the 777 MLG a difference is the steerable axle has no brakes fitted.

http://www.airliners.net/open.file/862877/L/

SMOC

[Halfnut]

SMOC,

Thanks for the link to the underside of the A380 but the photos of the tires getting the scuffing/skidding appear to be the four wheel trucks mounted outboard on the wings.

[aintsaying]

Looks like to me this occured during a sharp left turn when pushing the aircraft backwards. Straighten the nose wheels and pull foward, dosen't look like any damage done from these shots. Would like to see a better shot from a few more feet back.

[kiwiman]

I take it, picture 2 and 3 are of a different set of gear - the skid marks don't match up..........

[ZAGORFLY]

Guys!!
1)in my opinion that is an IL86 not a 747, is too low over the wheels plus those brake vents are not boeing (close guess?)
2) The body gear is not steerable,
3) it looks really a test , Who would be there during a Pusch back getting pictures?
4) the kind of tarmac...russian airport?

Sorry Guys!!!
I still think that it is a IL86 however it could be an A 340-600
3 boogies twin tandem MLG
the picture are referring most probably to a test since you can notice in one picture one red ban from a lock pin still in place to avoid the accidental retraction or gear collapse.
in another pics you can see also an observer jusr in the back ground (he looks russian...)sorry. Have a nice day whatever you are.

[Beanbag]

Assuming the pics are genuine, the fact that Airbus put a copyright notice on them suggests they intended them to get out, which in turn suggests that they at least don't think they are commercially embarrassing. (Though I only did Kremlinology 101, not the advanced stuff)

[circseam]

"You cant get better than a quick fit fitter"

On another note, how much weight would of been saved by not having the steerable system?

[PPRuNeUser0162]

stefanoperer - do you seriously believe that's an IL86??? As you said, look at the brake vents and then look at the picture in the link posted by SMOC...

They look the same to me... :hmm:

[Barry Cuda]

Can we assume that Airbus will be lobbying for chicanes on the high speedturn offs at major airports? If they don't get them will they advise the airlines not to land at that airport...?

[sky330]

Take any heavy wide-body, make a tight 90 degrees turn and stopped immediately before rolling forward.

Go down and look at your gear, it's not so extreme but if you have never saw it, I can guaranteed you'll be surprised.

Or look at the gears and tyres during a 180 at minimum radius.

Guess why they say to roll forward at least one fuselage length to remove the stress on gears and tires....

I remerbered vividly the fights with marshaller and tower in Bamako that's absolutly want our 330's to be put in the extreme corner of the apron... :{

For a test at the limit these pictures really don't surprised me.

[jewitts]

I suppose it won't be able to use Orly then?

[Bmused55]

stefanoperer

Show me an IL86 with 4 wheel wing bogies and 6 wheel Body bogies and you might have some credability.

Otherwise, your talking rubbish.

[boofta]

Dear Sky330
It's all well and good to roll forward a fuselage length, but who
will be liable for repairing the tarmac after each 90 degree lineup?

6 months late, 12 month's late

[sky330]

boofta,

Obviously the airport,
now that may put some braking force on the acceptance of A380's from some airport, if it is more a problem than with other wide-bodies.

In quite a few african airports, every aircraft have to make an 180 after every landing or before every take-off, and runway suffered a lot when you do that with a wide-body at MTOW. Still it is an accepted procedure by everyone,
Airport authorities pay the bill for the tarmac, airlines pay the bill for tyres and landing gear maintenance...

[keel beam]

All this fuss about slightly distorted tyres!!! Sky330 is on the right track. I suggest that if any of you sky jockeys have a chance to see a push back from the outside than you will see how much a tyre deforms on a sharp turn...pause for breath... The worn shoulder can be seen on some body gears of Jumbos. So gents/ladies do not fret. The tyres can take it!

[Bmused55]

clearly not on the A380.

I've seen tires deform on push back with tight turns... but never seen the tire come off the rim like this.

[Dr Dave]

Maybe this is my (large-scale) ignorance, but I don't see categorical evidence from the three pics that any of the tyres are off the rim.

Can someone please point out the evidence that a tyre is actually off the rim, rather than being in a highly deformed state, but with the strain within the tyre originating from the rim?

Do aircraft tyres stay inflated when off the rim - all of the tyres here look inflated to me?

[HotDog]

55, I can now see why you call yourself an artist. I am bemused.:}

[Bmused55]

Perhaps off the rim was an incorrect assessment.

Naturaly I meant that these tires have deformed a considerable ammount. And judging by the skid marks have been dragged a good bit.

[El lute]

Beanbag,
Where have you seen an Airbus copyright on any of the three pictures?

[Dr Dave]

El lute

Err - that big notice saying (c) Airbus on the bottom right of each picture is a hint, I would say? ;-))

[El lute]

Beanbag, Dr Dave
Sorry, I seem not to be my usual sharp self.:O

[thefacts]

The test is a normal part of the ground testing of the aircraft, and the results exceeded expectations - the gear is tested to failure. All is fine. The test consists of towing the aircraft, at maximum weight, forward, backward, in normal turns, in tight turns, and laterally. The goal is to assess the landing gear's structural integrity in all directions in abusive cases. The test does not replicate normal aircraft operations.

Below is a story that was posted on Flight International's on-line daily news service - Air Transport Intelligence:

A380 tyres withstand extreme handling tests: Airbus
London (15Jul05, 12:01 GMT, 174 words)
Airbus is claiming that the undercarriage and tyres on its A380 aircraft have performed as expected after being subjected to extreme ground-handling tests last month.
Images show that the tests resulted in deformation and damage to the aircraft’s Michelin tyres but that they performed “at and above” expected levels during the abusive ground-handling tests on 25 June.

The A380 main undercarriage comprises two four-wheel under-wing bogies and, behind them, two six-wheel fuselage-mounted bogies. The rear axle of the six-wheel bogie is normally steerable during push-back and taxiing.
But unless electrical power is supplied to the aircraft during towing - by the aircraft or from generators on the tow-tractor - the axle remains locked.

Airbus states that the undercarriage tests were designed to take the undercarriage and tyres “way beyond the limit of normal operations” and adds: “[The tests] were the equivalent of the structural static airframe tests to destruction.
“Although these tests were designed to test up to maximum deformation and beyond, the gear did exactly what it is supposed to do.”

[GGV]

thefacts - I have to say that your crude effort to deflect speculation and the repeated excercise of bias by the introduction of inconvenient facts is unlikely to work. But it's a nice try nonetheless!

[Leftit2L8]

Have to say, thefacts seems pretty convincing to me. Don't see any reason to be critical at all.

[BahrainLad]

GGV's sarcasm doesn't come across well on the telewebnet....

"Why let the facts get in the way of a good story" indeed.

[Captain104]

Gentlemen,

sorry to disappoint you and your expectations or theories. "Thefacts' s" infos are correct. Forget all the fuss about it. Ask your tech. or fleet pilots in your company involved in introducing the A 380. They (we) are always keen to explain, but not in a public forum.
What a bowl of experts here. :*

Regards

[Flying Torquewrench]

According the following link to a newspaper THEFACTS is right.

http://money.excite.com/jsp/nw/nwdt_rt.jsp?section=news&cat=INDUSTRY&feed=dji&news_id=dji-00081820050715&date=20050715

[mtogw]

http://images.airliners.net/open.file?id=862877&WxsIERv=Nveohf%20N380-841&WdsYXMg=Nveohf%20Vaqhfgevr&QtODMg=Cnevf%20-%20Yr%20Obhetrg%20%28YOT%20%2F%20YSCO%29&ERDLTkt=Senapr&ktODMp=Whar%2019%2C%202005&BP=0&WNEb25u=Oreaneq%20Puneyrf&xsIERvdWdsY=S-JJBJ&MgTUQtODMgKE=Cnevf%20Nve%20Fubj%202005.%20N380.%20Znva%20trn e%20unf%2020%20jurryf%20%21%21%21&YXMgTUQtODMgKERD=8532&NEb25uZWxs=2005-06-20%2005%3A07%3A29&ODJ9dvCE=51&O89Dcjdg=001&static=yes&width=1024&height=695&sok=JURER%20%20%28nvepensg%20%3D%20%27Nveohf%20N380-841%27%29%20%20beqre%20ol%20cubgb_vq%20QRFP&photo_nr=44&prev_id=863012&next_id=862819&size=L
For thsoe that think it isnt the 380

[ZAGORFLY]

I may be wrong, but what I see are 3 legs with 4 whells each
the only two candidate in this configuration are IL86 and A340-600
Yes I understand that the pics is even coming from the Airbuss gallery but the clearance from the body and he whells does'nt look to me the one of the 600.
I may be probably very Wrong, anyway great pics amazing stress test. I can't really figure out how this can happen. Where is the center of rotation ?

I apologize to every body to bothering about the IL86 story.
But I couldn\'t see even the body reflection the 3rd axel of the Body Landing gear. bye

[aintsaying]

I agree with Captain104.
See page two for my comments.

[Bmused55]

I'm convinced by "TheFacts" information.

Good to hear the gear passed the test.

[BRAKES HOT]

i've seen these before. they are pictures from intentionally destructive testing...

[ChristiaanJ]

"... pictures from intentionally destructive testing ... "

Maybe a dumb question, but was this F-WWOW?
If so, are they sure the gear was not over-stressed or are they replacing the gear?
And what about the structure around the attachment points?

[Iceland]

The pictures were taken on 25 June during ground load testing as
part of the standard aircraft verification test. The aircraft was at
maximum ramp weight with rear C of G position and no body gear steering
(steerable aft axle) available. The aircraft was then towed and pushed into
turns at maximum nose gear steering angles. In these 'worst case' scenarios
the strains on the gear are measured to ensure structural integrity. The
tests confirmed that, given the gear deformation built up, no tug driver
would ever bring the aircraft to the extreme steering angles achieved
during this particular load testing.

[S2A Pictures]

Like all new aircraft, weight under stress tests are necessary.

By the look of it, that's exactly what these images illustrate.

Turn the nosewheel, full opposite power and watch what happens.

Will the tyres come off the rims?

Will the tyres burst?

Will the carriage bend as it is supposed to?

All quite normal.

Panic over.

Err, like what Iceland said ...

[moggiee]

All covered in the Flight international article wasn't it? Tests designed to push the gear beyond limits to assess how much abuse the gear can take.

I wonder how close the origin of the scare stories was to Seattle?

[Halfnut]

Air Transport

Airbus A380 Gear Put Through Drills

Aviation Week & Space Technology

07/25/2005, page 42

Michael A. Dornheim
Los Angeles
Robert Wall
Paris

A380 tires damage airport surface during 'abusive' turn test

Gear Concerns

Airbus is being forced to respond to Internet-circulated pictures of A380 tow tests, which show the landing gear carving grooves in the asphalt during turns sharper than normal limits. Reaction pushed the company to issue a letter to "airline focal points" on July 19.

Officials at Airbus and Goodrich, which engineered and builds the main landing gear, insist the results validate their design and they do not plan any changes. "Although spectacular for the non-specialist, actual deformations are not as high as on some other aircraft," Airbus wrote to the airlines. "Preliminary results confirm the design values of loads and deformations."

But while they are happy with the gear, others--such as airport operators--see the torn tarmac and wonder what will happen to their property. Some want more information, such as how strong the damaged asphalt was.

The June 25 tow tests at Toulouse were intended to stress the landing gear during "abusive cases" outside normal operation, Airbus says. During the trials, the gross weight was 546 metric tons (1,204,000 lb.); maximum takeoff weight for the aircraft is 560 tons. The tests consisted of "towing and pushback maneuvers at high weight, with various nose-landing-gear steering angles ranging from typical operational values up to extreme cases, close to bottoming of steering actuators, beyond the allowed towing/pushback limits," Airbus says.

Maximum steering angle for the A380 during towing will be restricted to a standard 60 deg., Airbus says. The tests were performed at 60 deg. and higher, reaching a maximum of 72 deg.

"Given the gear deformation buildup, no truck driver would ever bring the aircraft to the extreme steering angles achieved during this particular loads testing," Airbus says.

The A380 has four main landing gear, two on the body with six-wheel trucks and two on the wing with four-wheel trucks. The wing gear are forward of the body gear. On an aircraft with a simpler single-axle main landing gear, the axes of the nosewheel and the main wheels intersect at the center of the turning radius. But multiple main gear axles form parallel lines that can't intersect at the turning center, and some of the tires have to scrub laterally in a turn. The sharper the turn, the more they scrub. The Boeing 747 alleviates this problem by steering the body gear at low speeds so the axes point toward a common turning center, which reduces scrubbing.

THE ENTIRE A380 body gear doesn't steer, but the aft axle does steer on the six-wheel trucks. If the body steering mechanism is inoperative, the A380 can be dispatched with the wheels aligned and locked. The wing gear do not steer at all. In these photos, it is the wing gear that are scrubbing. The tests were the first in a series to check A380 ground handling. In August-September, Airbus plans to assess minimum turn radius at heavy weight and taxiing the aircraft with engines running. U-turns are also on the to-do list.

Airbus officials have begun trying to explain the situation, saying the tests marked a positive step in verifying that the A380 can taxi using FAA Design Group V or ICAO Code E runway/taxiway systems--a standard measure for those surfaces.

FOR THE JUNE 25 TEST, body wheel steering was deactivated. The aircraft was near its maximum weight, with an aft center of gravity, to represent a worst-case condition. The test procedure consisted in towing/pushing the aircraft out and into a turn. When the turn radius was stabilized, the aircraft was stopped, and pictures of the landing gear were taken.

Airbus officials note that given the roughly 90F temperature on the day of the test, and the fact that the aircraft was turned beyond set limits, "it is not abnormal to have some local deterioration of the asphalt." But one airport official quipped: "Ninety degrees? Is that all?"

Three tires were replaced after the test. This wasn't mandatory, Airbus says, but helped with the flight test schedule.

Airbus expects the A380 to be able to perform U-turns in a similar or smaller space than the A340-600 due to its shorter wheelbase. Moreover, the company points out that with 20 main landing gear wheels, the per-wheel weight on the A380 is lower than Boeing's 777-300ER.
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