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Middle Landing Gear On Airbus 340  
User currently offlineOasis From Canada, joined May 2008, 62 posts, RR: 0
Posted (5 years 10 months 1 week 3 days 2 hours ago) and read 5880 times:

Hi
I was wondering what would happen to an A340-200/300 if the middle gear (the one under in between the wings) would be removed (if that is even possible to just have it be removed?) Would the middle part of the fuselage collapse? Because the only difference between an A330-300 and an A340-200/300 is that one has 4 engines, and the A330 doesn't have any gear in the middle. Is it a weight issue? I think I remember seeing a picture of a CX A340 at Kai Tak without the middle gear.

I hope that made sense :P

-Ben


Aeroflot can fly Moscow to LA, I bet your airline can only fly half way
24 replies: All unread, jump to last
 
User currently offlineWILCO737 From Greenland, joined Jun 2004, 8890 posts, RR: 76
Reply 1, posted (5 years 10 months 1 week 3 days 2 hours ago) and read 5871 times:
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Quoting Oasis (Thread starter):

Hi,

I guess this thread should be in Tech/ Ops.

I am not 100% sure for the A340. But for the MD11 you can remove the center landing gear as well. Or let it be retracted. Nothing would collaps but you have a huge reduction in the maximum weights. The MTOW reduces to 220 tons instead of 286 tons. Same for the landing weight. But I don't know the figures there.
So I bet it is possible for the 340 as well. And nothing would collapse.

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineVikkyvik From United States of America, joined Jul 2003, 9388 posts, RR: 27
Reply 2, posted (5 years 10 months 1 week 3 days 2 hours ago) and read 5843 times:
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Quoting WILCO737 (Reply 1):

I am not 100% sure for the A340. But for the MD11 you can remove the center landing gear as well. Or let it be retracted. Nothing would collaps but you have a huge reduction in the maximum weights. The MTOW reduces to 220 tons instead of 286 tons. Same for the landing weight. But I don't know the figures there.
So I bet it is possible for the 340 as well. And nothing would collapse.

Hey WILCO, is it on the MD-11 that the center gear is non-load bearing at lighter weights? As in, it'll actually be off the ground?

I'm pretty sure that's the case for EITHER the MD-11 or the A340....but I don't remember which one.

However, there have been cases when the center gear is inoperable for some reason. The airplane can still fly (I guess the center gear gets MEL'd?), but I'd think the weights are reduced, as Phil said.

Here we go, found one:


View Large View Medium
Click here for bigger photo!

Photo © Mark McWhirter - Contrails Aviation Photography



There used to be a photo with a Cathay Pacific 340 at Kai Tak....but couldn't find that one.



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineBuckfifty From Canada, joined Oct 2001, 1316 posts, RR: 20
Reply 3, posted (5 years 10 months 1 week 3 days 2 hours ago) and read 5843 times:



Quoting Oasis (Thread starter):
Hi
I was wondering what would happen to an A340-200/300 if the middle gear (the one under in between the wings) would be removed (if that is even possible to just have it be removed?) Would the middle part of the fuselage collapse? Because the only difference between an A330-300 and an A340-200/300 is that one has 4 engines, and the A330 doesn't have any gear in the middle. Is it a weight issue? I think I remember seeing a picture of a CX A340 at Kai Tak without the middle gear.

The middle gear itself can be stowed in the uplocked position, with a reduced Max Ramp Weight / Max Takeoff Weight. Otherwise it has no effect at all on the Max Landing Weight. In effect, without the centre gear, the weights which the A340 operate at are more or less those of a maxed out A330. However, this obviously depends on what configurations / standard either aircraft are built to when you do the comparison.

The centre gear itself is not a landing load bearing gear. Therefore, if we had a main gear stuck in the stowed position, we must land without the centre gear in order not to damage the fuselage. The only way to do that is via a gravity extension.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 4, posted (5 years 10 months 1 week 3 days 2 hours ago) and read 5842 times:

Definitely a weight issue. The 340 is designed for longer haul flights with higher weights.

You can probably retract it for maintenance purposes. As Wilco737 points out the MD11 can have it MELd. I believe it was MD11Engineer who posted the checklist for such an event, ending with "inform the pilots of the coming weight and balance nightmare".  Wink



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2128 posts, RR: 56
Reply 5, posted (5 years 10 months 1 week 3 days 1 hour ago) and read 5839 times:



Quoting Buckfifty (Reply 3):
The centre gear itself is not a landing load bearing gear.

What else is its function then-- ornamentation?

Or is it something having to do with the bearing capacity of aprons and taxiways?


User currently offlineBuckfifty From Canada, joined Oct 2001, 1316 posts, RR: 20
Reply 6, posted (5 years 10 months 1 week 3 days 1 hour ago) and read 5835 times:



Quoting WingedMigrator (Reply 5):
Or is it something having to do with the bearing capacity of aprons and taxiways?

As far as I understand it, yes.


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8890 posts, RR: 76
Reply 7, posted (5 years 10 months 1 week 3 days 1 hour ago) and read 5832 times:
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Quoting Vikkyvik (Reply 2):
Hey WILCO, is it on the MD-11 that the center gear is non-load bearing at lighter weights? As in, it'll actually be off the ground?

As far as I know, it has always contact to the ground. Even at lighter weight. I think it was the 340 where it is "airborne" when empty.

Quoting Starlionblue (Reply 4):
As Wilco737 points out the MD11 can have it MELd. I believe it was MD11Engineer who posted the checklist for such an event, ending with "inform the pilots of the coming weight and balance nightmare". Wink

Oh yeah, the weight and balance nightmare. For us cargo it doesn't make any sense to fly without that gear. You cannot take much load with you then. So, better get a new one first  Wink

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineMir From United States of America, joined Jan 2004, 21077 posts, RR: 56
Reply 8, posted (5 years 10 months 1 week 2 days 23 hours ago) and read 5782 times:



Quoting WingedMigrator (Reply 5):
Or is it something having to do with the bearing capacity of aprons and taxiways?

Precisely. Only eight main wheels puts too much load on each for the taxiways to bear. Thus the 340 has ten. The 340NG and 777 have twelve (though the 777 has no center gear). You can go without the center gear on the 340 or MD11, but you're going to be weight restricted so as to not exceed taxiway strength limits.

Until recently, 777-300s and 340-600s couldn't use the taxiway bridges at JFK due to the fact that despite the extra wheels, they still have very high pavement loading, more than what the bridges could withstand. The bridges have since been rebuilt and now there are no restrictions.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineBA777 From United Kingdom, joined Jun 2001, 2167 posts, RR: 7
Reply 9, posted (5 years 10 months 1 week 2 days 22 hours ago) and read 5753 times:

Yep it has to do with the ACN and PCN numbers as mentioned by Mir  Smile

User currently offlineTristarsteve From Sweden, joined Nov 2005, 3928 posts, RR: 34
Reply 10, posted (5 years 10 months 1 week 2 days 22 hours ago) and read 5753 times:

An engineer friend of mine was working in Sanaa on the BA DC10 when it was a scheduled flight there. I think it was the last flight, anyway he had no spare mainwheel, and needed to change a wing gear wheel. So they removed a S wheel from the centre gear and fitted it on the wing posn, then retracted the centre gear and flew the aircraft back to LGW.

User currently offlineHAWK21M From India, joined Jan 2001, 31568 posts, RR: 57
Reply 11, posted (5 years 10 months 1 week 2 days 20 hours ago) and read 5713 times:



Quoting Tristarsteve (Reply 10):
An engineer friend of mine was working in Sanaa on the BA DC10 when it was a scheduled flight there. I think it was the last flight, anyway he had no spare mainwheel, and needed to change a wing gear wheel. So they removed a S wheel from the centre gear and fitted it on the wing posn, then retracted the centre gear and flew the aircraft back to LGW.

Interesting.Reminds me of the MEL move on B752 using the serviceable secondary EICAS display on the u/s EHSI position
 Smile
regds
MEL



Think of the brighter side!
User currently offlineOasis From Canada, joined May 2008, 62 posts, RR: 0
Reply 12, posted (5 years 10 months 1 week 2 days 9 hours ago) and read 5545 times:

thanks for the help guys  Smile and sorry about posting in the wrong forum


Aeroflot can fly Moscow to LA, I bet your airline can only fly half way
User currently offlineFlynavy From , joined Dec 1969, posts, RR:
Reply 13, posted (5 years 10 months 1 week 2 days 9 hours ago) and read 5537 times:



Quoting Buckfifty (Reply 3):
The centre gear itself is not a landing load bearing gear.

 checkmark  This photo clearly shows this:
View Large View Medium
Click here for bigger photo!

Photo © Tango3 - Team Ninervictor



User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 14, posted (5 years 10 months 1 week 2 days 8 hours ago) and read 5523 times:



Quoting WingedMigrator (Reply 5):
is it something having to do with the bearing capacity of aprons and taxiways?



Quoting Buckfifty (Reply 6):
As far as I understand it, yes.

For sure, here in the US, load bearing capacity for airports is driven by wheel configuration.

However, I always assumed, from the placement, that it was specifially increase max zero-fuel weight including weight from centerline tanks which, structurally, behaves like payload.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineAskr From Poland, joined Mar 2008, 45 posts, RR: 0
Reply 15, posted (5 years 10 months 1 week 1 day 23 hours ago) and read 5435 times:

There is a pic in the database of a Varig MD11 or DC-10, cant recall, where the middle landing gear... fell off. Well, at least the bogey.

Maybe MD11 will have a pic of that somewhare  Smile



ATC-PL Wanabe :) - 2nd application is in... 11 July...
User currently offlineBuckFifty From Canada, joined Oct 2001, 1316 posts, RR: 20
Reply 16, posted (5 years 10 months 1 week 1 day 12 hours ago) and read 5331 times:



Quoting SlamClick (Reply 14):
However, I always assumed, from the placement, that it was specifially increase max zero-fuel weight including weight from centerline tanks which, structurally, behaves like payload.

The 333 and 343 both have very similar MZFW's. And without the centre gear down, the 343 is limited to a MTOW which is, again, similar to that of a 333.

With the MLW virtually the same for both aircraft, one would assume that the centreline gear is indeed there to increase the MTOW / MRW, by increasing the footprint for a lower ACN.

The centre tank on the 340, incidentally, is an integral tank in the wingbox, which is different than the pallet loaded ACT. Not sure if anyone uses those anymore...


User currently offlineAskr From Poland, joined Mar 2008, 45 posts, RR: 0
Reply 17, posted (5 years 10 months 1 week 1 day 12 hours ago) and read 5327 times:



Quoting Askr (Reply 15):
There is a pic in the database of a Varig MD11 or DC-10, cant recall, where the middle landing gear... fell off. Well, at least the bogey.

Maybe MD11 will have a pic of that somewhare

Damn, it was supposed to be WILCO737  Wink
Sorry for the mixup  Wink



ATC-PL Wanabe :) - 2nd application is in... 11 July...
User currently offlineVikkyvik From United States of America, joined Jul 2003, 9388 posts, RR: 27
Reply 18, posted (5 years 10 months 1 week 1 day 11 hours ago) and read 5295 times:
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Quoting WILCO737 (Reply 7):
As far as I know, it has always contact to the ground. Even at lighter weight. I think it was the 340 where it is "airborne" when empty.

OK, that's what I thought. Thanks.

Quoting Askr (Reply 17):
Damn, it was supposed to be WILCO737

That's his fault for switching aircraft on us  Wink



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineWILCO737 From Greenland, joined Jun 2004, 8890 posts, RR: 76
Reply 19, posted (5 years 10 months 1 week 1 day 3 hours ago) and read 5230 times:
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Quoting Askr (Reply 17):
Damn, it was supposed to be WILCO737 Wink

 rofl   Wink

No, I don't have a pic of it without the center gear.

Quoting Vikkyvik (Reply 18):
That's his fault for switching aircraft on us Wink

Won't happen for enother 2 more years  Wink hehe

WILCO737 (MD11F) in 2 years (B744)  duck 
 airplane 



It it's not Boeing, I am not going.
User currently offlineAirbus_A340 From Hong Kong, joined Mar 2000, 1560 posts, RR: 19
Reply 20, posted (5 years 10 months 1 week 13 hours ago) and read 5125 times:

Something you might find interesting, when unloaded, the A340 centre landing gear doesn't touch the ground, it hangs a couple of inches off the ground, until loading/refuelling.


People. They make an airline. www.cathaypacific.com
User currently offlineAskr From Poland, joined Mar 2008, 45 posts, RR: 0
Reply 21, posted (5 years 10 months 1 week 10 hours ago) and read 5087 times:

Found it


View Large View Medium
Click here for bigger photo!

Photo © Allan K. B. Ramos


Now I wonder what sort of red stuff on the control panel this incident brought...



[Edited 2008-06-13 15:20:56]


ATC-PL Wanabe :) - 2nd application is in... 11 July...
User currently offlineViscount724 From Switzerland, joined Oct 2006, 24061 posts, RR: 23
Reply 22, posted (5 years 10 months 6 days 7 hours ago) and read 4948 times:



Quoting WILCO737 (Reply 1):
But for the MD11 you can remove the center landing gear as well. Or let it be retracted. Nothing would collaps but you have a huge reduction in the maximum weights.

Reminds me of the following incident involving a World Airways MD-11F departing ANC on a 2-engine ferry flight with the center landing gear retracted.
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20041020X01664&key=1

Longer version:
http://www.ntsb.gov/ntsb/brief2.asp?...020X01664&ntsbno=ANC05IA002&akey=1


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8890 posts, RR: 76
Reply 23, posted (5 years 10 months 6 days 2 hours ago) and read 4914 times:
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Quoting Viscount724 (Reply 22):
Reminds me of the following incident involving a World Airways MD-11F departing ANC on a 2-engine ferry flight with the center landing gear retracted.
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20041020X01664&key=1

Longer version:
http://www.ntsb.gov/ntsb/brief2.asp?...key=1

Oops, something went wrong here  Wink

Thanks for the links, never heard of that incident.

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineDocLightning From United States of America, joined Nov 2005, 18666 posts, RR: 58
Reply 24, posted (5 years 10 months 5 days 17 hours ago) and read 4859 times:



Quoting WILCO737 (Reply 23):
Oops, something went wrong here

I'm only imaging the language in the cockpit. Can you imagine? You apply TO thrust and suddenly you're rotating without having moved anywhere?


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