by188b
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MD-11 Landing Without Central Landing Gear Down?

Sun Jun 26, 2011 11:43 am

Viewed this photo of a MD-11 landing


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Photo © Antti Salo




The aircraft is landing without its centre landing gear down, in what instances would this happen? The photo comments state its rare but is done sometimes.
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CosmicCruiser
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RE: MD-11 Landing Without Central Landing Gear Down?

Sun Jun 26, 2011 1:12 pm

Obviously a problem with the center gear. I've had it once when there was a hydraulic leak at the ctr gear. It was deferred up and we flew CDG-MEM without it. You take a big wgt penalty.
 
474218
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RE: MD-11 Landing Without Central Landing Gear Down?

Sun Jun 26, 2011 1:57 pm

The MD-11 can be operated with the "center gear" retracted, and stowed, provided the aircraft weights are adjusted in accordance with the AFM.
 
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ATA L1011
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 4:18 am

Quoting 474218 (Reply 2):
The MD-11 can be operated with the "center gear" retracted, and stowed, provided the aircraft weights are adjusted in accordance with the AFM.


Exactly, same goes with the DC-10-30/40. Quite often JAL use to operate the 40 with the center gear stowed.
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Max Q
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 5:24 am

I understand operating with the centre gear retracted for maintenance reasons,


But why would you want to keep it retracted otherwise ?



You will have a higher weight 'footprint' on the remaining gear.




I must be missing something, what is the point ?
The best contribution to safety is a competent Pilot.
 
wilco737
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 5:47 am

Quoting Max Q (Reply 4):
But why would you want to keep it retracted otherwise ?

Maybe some problems with the retraction mechanism. So you can fly it with center gear retracted. And of course you have weight restrictions. There are charts how to adjust your MTOW and MLAW etc etc.

Quoting Max Q (Reply 4):
You will have a higher weight 'footprint' on the remaining gear.

Yes, you will. But due to the lower allowable weights the difference isn't too high. There are charts for that case as well where you can check where you can land and take off.

wilco737
  
 
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LAXintl
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 6:58 am

As I recall JAL actually physically removed the center gear on some of its DC-10-40 fleet in later years as they served domestic and regional routes which operated at low weights anyhow.
The removal of the gear reduced the empty weight of the aircraft which helped reduce fuel burn.

I also recall from a friend down at MDC, that Fedex was looking to do the same on its DC-10-30 fleet following the introduction of the MD-11, as the DC-10-30 no longer operating long haul services for FX being relegated back into domestic only. I never heard what the final outcome was.
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LAXintl
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 7:08 am

This quite old thread makes mention of both JAL and Condor in Germany removing the center gear.
http://www.airliners.net/aviation-forums/tech_ops/print.main?id=83372
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413X3
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 8:11 am

The DC-10-10 didn't have a center landing gear, did the MD-11 ever have this option? I would imagine if you always fly below max weights you can remove it to save on maint costs.
 
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Starlionblue
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 11:57 am

Quoting wilco737 (Reply 5):
Quoting Max Q (Reply 4):
But why would you want to keep it retracted otherwise ?

Maybe some problems with the retraction mechanism. So you can fly it with center gear retracted. And of course you have weight restrictions. There are charts how to adjust your MTOW and MLAW etc etc.

I recall a thread years ago where MD11Engineer gave an abbreviated checklist for dispatching without the center gear. The last item was "inform the pilots of the upcoming weight and balance nightmare". 
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wilco737
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 12:07 pm

Quoting Starlionblue (Reply 9):
The last item was "inform the pilots of the upcoming weight and balance nightmare". 

Excellent  Sounds scary  

I never had a flight without center gear, so I never took a real close look at the charts, but I am sure the restrictions are quite high...

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474218
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 12:29 pm

Quoting 413X3 (Reply 8):
I would imagine if you always fly below max weights you can remove it to save on maint costs.


Permanent removal of the center gear would require a Service Bulletin (or STC) as operation using the MMEL is limited. In the case of the MD-11 Center Gear it is ten (10) calendar days.
 
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LAXintl
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 6:16 pm

Checked with a friend who was with MDC in the 70/80s and had the following.

Off the top of his head he says JAL indeed removed the center-gear of aircraft, and matter of fact had some DC-10-40D (domestic ops) delivered from LGB sans the center-gear. In later years they removed them off the DC-10-40I (Intl version) when they stopped doing long-haul.

He also says he recalls there an analysis done with Air NZ that showed and eventually had them operate its trans-Tasman services to Australia with the gear retracted as the procedure would lower landing fees on the aircraft for the airline.

He also states he believe it was CP Air in Canada would operate with retracted gear sometimes when aircraft flew shorter haul stuff. Plus he recalls UK operator (maybe Laker) that did the same with its -30s when they ran charters to places like Spain which also was result of landing fee savings.
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bohica
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RE: MD-11 Landing Without Central Landing Gear Down?

Mon Jun 27, 2011 7:47 pm

Quoting 474218 (Reply 2):
The MD-11 can be operated with the "center gear" retracted, and stowed, provided the aircraft weights are adjusted in accordance with the AFM.

According to the following link you can do the same with an A340:

http://www.pprune.org/tech-log/11935...ada-a340s-without-centre-gear.html

[Edited 2011-06-27 12:49:29]
 
Viscount724
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RE: MD-11 Landing Without Central Landing Gear Down?

Tue Jun 28, 2011 1:53 am

Quoting Starlionblue (Reply 9):
Quoting wilco737 (Reply 5):
Quoting Max Q (Reply 4):
But why would you want to keep it retracted otherwise ?

Maybe some problems with the retraction mechanism. So you can fly it with center gear retracted. And of course you have weight restrictions. There are charts how to adjust your MTOW and MLAW etc etc.

I recall a thread years ago where MD11Engineer gave an abbreviated checklist for dispatching without the center gear. The last item was "inform the pilots of the upcoming weight and balance nightmare"

Reminds me of the following World Airways MD-11F incident at ANC on a 2-engine ferry flight to ATL with the center gear retracted. The crew was apparently unaware that this significantly changed the weight and balance and when power was applied for takeoff the tail tipped backwards and struck the runway. Apparently the change in center of gravity with the center gear retracted does not affect the DC-10, and the MD-11's 2-engine ferry manual was copied from the DC-10 manual and thus did not mention the C of G shift with the center gear retracted on the MD-11.
http://www.ntsb.gov/aviationquery/br...ef.aspx?ev_id=20041020X01664&key=1

Click the link at the bottom for detailed report.

[Edited 2011-06-27 18:58:15]

[Edited 2011-06-27 18:59:18]
 
Max Q
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RE: MD-11 Landing Without Central Landing Gear Down?

Tue Jun 28, 2011 3:27 am

Quoting LAXintl (Reply 12):


He also says he recalls there an analysis done with Air NZ that showed and eventually had them operate its trans-Tasman services to Australia with the gear retracted as the procedure would lower landing fees on the aircraft for the airline.

He also states he believe it was CP Air in Canada would operate with retracted gear sometimes when aircraft flew shorter haul stuff. Plus he recalls UK operator (maybe Laker) that did the same with its -30s when they ran charters to places like Spain which also was result of landing fee savings.

I have heard this before as well but it still doesn't make sense, leaving the centre gear retracted does not 'make the Aircraft lighter'


Unless, by leaving it retracted you are 'proving' you are staying under the weight limits for that configuration thus lowering
your landing fees.
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LAXintl
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RE: MD-11 Landing Without Central Landing Gear Down?

Tue Jun 28, 2011 4:23 am

Quoting Max Q (Reply 15):
I have heard this before as well but it still doesn't make sense, leaving the centre gear retracted does not 'make the Aircraft lighter'
Unless, by leaving it retracted you are 'proving' you are staying under the weight limits for that configuration thus lowering
your landing fees.


Yeah basically without the gear the max certified operating weights are less, so the gross number which things like overflight and landing fees are computed is lower.

A bit akin to British Airways which has a portion of its 747-400 fleet known as 744 Lite, operating sans the tail tank plumbing and lower gross weight. The model is mostly used on shorter London-East Coast services with lower OEW and structural weights which save it money at the end of the day.
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glen
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RE: MD-11 Landing Without Central Landing Gear Down?

Wed Jun 29, 2011 2:38 pm

Quoting wilco737 (Reply 10):
but I am sure the restrictions are quite high

I just checked my old books: MTOW 201.8t (cntr gear retracted) vs. 286t
MLW 181.4t vs. 199.5t (pax version)
Quite an impressive weight penalty.
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wilco737
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RE: MD-11 Landing Without Central Landing Gear Down?

Wed Jun 29, 2011 3:59 pm

Quoting glen (Reply 17):
I just checked my old books: MTOW 201.8t (cntr gear retracted) vs. 286t
MLW 181.4t vs. 199.5t (pax version)
Quite an impressive weight penalty.

Thanks. I put my books already away so that I couldn't look it up.

It is indeed impressive how many weight you have to reduce.

wilco737
  
 
futureatp
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RE: MD-11 Landing Without Central Landing Gear Down?

Sat Jul 02, 2011 9:37 am

My 2cents...

The fuel capacity on the DC10-30 (-40 as well) and MD11 is much higher than the -10 model. I dont have my charts with me but all of the additional fuel on the -30 is in the center aux tank. The MD11 also has an additional small tail tank. But with the extra weight of the fuel requires the center landing gear. If your not going to carry the fuel the center gear would not be needed. I think the -30 holds around 36,000 us gal and the MD11 holds over 38,000 us gal. I cannot remember what the -10 holds but it may only be around 20,000us gal. Multiply by 6.7lbs a gallon... you got a lot of weight difference in full fuel.

All FX -30s that I see have their center gear and none of the their MX people have mentioned such a program to remove it.
 
CosmicCruiser
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RE: MD-11 Landing Without Central Landing Gear Down?

Sat Jul 02, 2011 4:28 pm

I'm not at home to see charts but the flight I did with the ctr gr up was wgt limited to 478,000 lbs best I remember. That was a big hit. We crossed the Atl at 410 best i recall and landed with min fuel.
 
qblue
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RE: MD-11 Landing Without Central Landing Gear Down?

Tue Jul 05, 2011 5:53 am

Well just a follow-on to the center landing gear question. Now that the MD11 have landed with the center gear retracted but they find out that they have a heavy load outbound. Can the gear be lowered while on ground or do they need jacks to lift the aircraft? Do they have to fly off again just to lower the gear?
 
Viscount724
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RE: MD-11 Landing Without Central Landing Gear Down?

Wed Jul 06, 2011 5:06 am

Quoting futureatp (Reply 19):
I think the -30 holds around 36,000 us gal and the MD11 holds over 38,000 us gal. I cannot remember what the -10 holds but it may only be around 20,000us gal. Multiply by 6.7lbs a gallon... you got a lot of weight difference in full fuel.

Per Boeing website aircraft data, standard usable fuel (without any optional tanks), in US gallons::

DC-10-10: 21,762 gal.
DC-10-30: 36.652 gal.
MD-11: 38,615 gal.
 
IFIXCF6
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RE: MD-11 Landing Without Central Landing Gear Down?

Thu Jul 07, 2011 3:20 am

Quoting qblue (Reply 21):
Well just a follow-on to the center landing gear question. Now that the MD11 have landed with the center gear retracted but they find out that they have a heavy load outbound. Can the gear be lowered while on ground or do they need jacks to lift the aircraft? Do they have to fly off again just to lower the gear?

The MD11 (and DC10-30/40) are capable of lowering the center gear both with hydraulic power or mechanical/gravity. Extending the center gear on the ground with hydraulics is not a good idea, and with the strut inflated will probably result in damage to the structure. This is due to the angle of the strut (not straight up/down). In maintenance, we would lower the gear with "freefall extension" and a deflated strut. With shraeder valve open, roll the tires back, until the downlock clicks in place, and service the strut. This assumes all else is good-i.e. no discrepencies on the gear.

Mike
 
FriendlySkiesUK
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RE: MD-11 Landing Without Central Landing Gear Down?

Sat Jul 16, 2011 1:59 am

This maybe a slight lead on from the question about the MD11 landing with the centre gear retracted.

If the aircraft was for example operating a short haul flight (below three hours) with the light load and it had been planned (for whatever reason) for the centre gear to be retracted for landing – would this effect breaking action?

If you were landing the MD11 on auto breaking ‘MAX’ would this mean you would need to have the centre gear down to achieve truly maximum breaking?

One would have thought so, as you’re putting the breaking energy through ten wheels not eight – but I thought I would ask the question.

Friendlyskiesuk
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