Airbus A380 Issue

IROC · IROC's Garage

From an email I received. The email went on to say that they also saw some signficant deflections in the main gear struts under these loads. The photo below shows what happens when you turn an A380 on the tarmac:

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 ...

IROC · IROC's Garage

Another pic:

widebody911 · widebody911's Garage

Send it down to Tyson @ TRE for some adjustments...

Is that the pavement that's chewed up, or is it leaving that much rubber behind?

IROC · IROC's Garage

That's chewed up pavement. I'm sure airport operators will love to see that.

Mike

widebody911 · widebody911's Garage

I'm not an aerospace engineer - and I don't play one on TV - but it seems like frickin' common sense to make something that big steerable.

There's a picture out there of some big cargo plane landing, and it's gear are pointing one way and the plane is pointing another.

Maybe SingPilot and others can shed some light.

IROC · IROC's Garage

Well for sure all aircraft tires take a royal beating in these situations, but it seems the massive size of the A380 is really exacerbating the problem.

Like you said, I'd like to hear feedback from the guys who know more about this.

Mike

Jims5543 · 08-03-2005, 06:03 AM

Oh my God!! Those tires are Michelins! The sidewalls are going to fail!! I am suprised Micheline has not sent a letter advising not to use the tires yet.

widebody911 · widebody911's Garage

Quote:

Originally posted by Jims5543
Oh my God!! Those tires are Michelins! The sidewalls are going to fail!! I am suprised Micheline has not sent a letter advising not to use the tires yet.

It's OK - they're going to put a chicane at the end of the runway to slow down the planes...

singpilot · 08-03-2005, 06:30 AM

I just assumed the French aircraft design team wanted to sell French tires. Almost (can't speak for the French designed types) every Pilot's Operating Handbook advises against locked wheel turns, for this very reason.

Those are pretty amazing pictures. Another (long list) reason to stay out of an Airbus.

island911 · 08-03-2005, 06:31 AM

per PBS.org:

Quote:

Due to recent technological advances, Airbus claims the A380 will be a more efficient plane than its rival, the 747.

Clearly, the AirBUS is newer . .. which means it must be better technologically.

. . .doesn't everyone know that?

Tim Hancock · 08-03-2005, 06:42 AM

I bet the problem is with the tug driver. Some one obviously tried to pivot the plane too sharply while ground positioning it.

Dantilla · 08-03-2005, 06:46 AM

A cousin is a mechanic on both Boeing and Airbus airliners. The term around the maintenance base is "Scarebus".

IROC · IROC's Garage

Quote:

Originally posted by Tim Hancock
I bet the problem is with the tug driver. Some one obviously tried to pivot the plane too sharply while ground positioning it.

This is a distinct possibility. The email mentioned that it was unknown whether the A380 was under it's own power or not at the time...

Mike

artplumber · 08-03-2005, 06:56 AM

Quote:

Originally posted by island911

Clearly, the AirBUS is newer . .. which means it must be better technologically.

. . .doesn't everyone know that?

I think you meant bigger is better?

What does this say about the rest of the plane (engineered from the ground up)?

Tim Hancock · 08-03-2005, 07:14 AM

I could give a rats butt about Airbus vs Boeing, but many aircraft can be damaged due to improper ground handling. Many aircraft have to have pins pulled on linkages, etc and published procedures followed before being towed by tugs. The skid marks obviously show that the plane was being improperly pivoted about that gear leg, it does not neccesarily have anything to do with the design of the aircraft.

artplumber · 08-03-2005, 07:42 AM

Quote:

Originally posted by Tim Hancock
The skid marks obviously show that the plane was being improperly pivoted about that gear leg, it does not neccesarily have anything to do with the design of the aircraft.

Tim, do those ground pullers have the pull to do this? (honest question)

singpilot · 08-03-2005, 07:57 AM

The tugs have the ability to move the aircraft even with locked brakes, or to pivot it with the gear scrubbing just like in the pictures. I suspect that is the case with these pics. You'll note these pics are from Airbus (copyright notice in lower right corner), so they are probably using them to illustrate what NOT to do, and to document the damage.

Tim Hancock · 08-03-2005, 08:03 AM

When the nose gear is pivoted 90 degrees and pushed or pulled at that angle, the inside main gear has to pivot, while the outer gear can roll around the larger radius. This is like when you are trying to turn sharp with a tractor. You stomp on the inside wheel brake and pivot around meanwhile, the inside wheel has to skid as it is not rolling.

What Tom said above is true about some aircraft, but by no means is this the majority.

I doubt this kind of ground handling is required at most airports (severe pivoting turns).

singpilot · 08-03-2005, 08:08 AM

What makes this plane different, is that there are 4 main gear trucks. Even if one truck pivots, the other is scrubbing. Looking closely at these pics (you can see which direction is forward and aft), this pivot happened with the plane moving backwards, meaning it was being pushed with a tug. Yes, this kind of manuvering is not required at any major airport, and in fact the handbooks give the minimum turning radius and maximum angle allowed on the nosegear.

This is what happenes when the book is not followed.

artplumber · 08-03-2005, 09:14 AM

So why not make all or some of the gear trucks steerable?

Some of the airports (eg/SFO, SeaTac) have pretty tight confines. In fact, if my sense of proportion is not out, getting this plane to an interior gate at Atlanta is going to require fairly tight turns.