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MD-11 Landing Without Central Landing Gear Down?  
User currently offlineby188b From United Kingdom, joined Jul 2003, 710 posts, RR: 0
Posted (3 years 5 months 5 days 15 hours ago) and read 8846 times:

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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24 replies: All unread, jump to last
 
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 1, posted (3 years 5 months 5 days 14 hours ago) and read 8794 times:

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.

User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 2, posted (3 years 5 months 5 days 13 hours ago) and read 8761 times:

The MD-11 can be operated with the "center gear" retracted, and stowed, provided the aircraft weights are adjusted in accordance with the AFM.

User currently offlineATA L1011 From United States of America, joined Feb 2001, 1388 posts, RR: 6
Reply 3, posted (3 years 5 months 4 days 23 hours ago) and read 8432 times:

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.



Treat others as you expect to be treated!
User currently offlineMax Q From United States of America, joined May 2001, 4751 posts, RR: 18
Reply 4, posted (3 years 5 months 4 days 22 hours ago) and read 8406 times:

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.
User currently offlinewilco737 From Greenland, joined Jun 2004, 9103 posts, RR: 76
Reply 5, posted (3 years 5 months 4 days 21 hours ago) and read 8396 times:
AIRLINERS.NET CREW
HEAD MODERATOR

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
  



It it's not Boeing, I am not going.
User currently offlineLAXintl From United States of America, joined May 2000, 26025 posts, RR: 50
Reply 6, posted (3 years 5 months 4 days 20 hours ago) and read 8358 times:

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.



From the desert to the sea, to all of Southern California
User currently offlineLAXintl From United States of America, joined May 2000, 26025 posts, RR: 50
Reply 7, posted (3 years 5 months 4 days 20 hours ago) and read 8348 times:

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



From the desert to the sea, to all of Southern California
User currently offline413X3 From United States of America, joined Jul 2008, 1983 posts, RR: 0
Reply 8, posted (3 years 5 months 4 days 19 hours ago) and read 8325 times:

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.

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17118 posts, RR: 66
Reply 9, posted (3 years 5 months 4 days 15 hours ago) and read 8238 times:

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". 



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinewilco737 From Greenland, joined Jun 2004, 9103 posts, RR: 76
Reply 10, posted (3 years 5 months 4 days 15 hours ago) and read 8234 times:
AIRLINERS.NET CREW
HEAD MODERATOR

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...

wilco737
  



It it's not Boeing, I am not going.
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 11, posted (3 years 5 months 4 days 15 hours ago) and read 8215 times:

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.


User currently offlineLAXintl From United States of America, joined May 2000, 26025 posts, RR: 50
Reply 12, posted (3 years 5 months 4 days 9 hours ago) and read 8083 times:

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.



From the desert to the sea, to all of Southern California
User currently offlinebohica From United States of America, joined Feb 2004, 2740 posts, RR: 0
Reply 13, posted (3 years 5 months 4 days 7 hours ago) and read 8017 times:

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]

User currently offlineViscount724 From Switzerland, joined Oct 2006, 25871 posts, RR: 22
Reply 14, posted (3 years 5 months 4 days 1 hour ago) and read 7850 times:

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]

User currently offlineMax Q From United States of America, joined May 2001, 4751 posts, RR: 18
Reply 15, posted (3 years 5 months 4 days ago) and read 7807 times:

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.



The best contribution to safety is a competent Pilot.
User currently offlineLAXintl From United States of America, joined May 2000, 26025 posts, RR: 50
Reply 16, posted (3 years 5 months 3 days 23 hours ago) and read 7791 times:

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.



From the desert to the sea, to all of Southern California
User currently offlineglen From Switzerland, joined Jun 2005, 225 posts, RR: 2
Reply 17, posted (3 years 5 months 2 days 13 hours ago) and read 7419 times:

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.



"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein
User currently offlinewilco737 From Greenland, joined Jun 2004, 9103 posts, RR: 76
Reply 18, posted (3 years 5 months 2 days 11 hours ago) and read 7385 times:
AIRLINERS.NET CREW
HEAD MODERATOR

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
  



It it's not Boeing, I am not going.
User currently offlinefutureatp From United States of America, joined Feb 2000, 222 posts, RR: 0
Reply 19, posted (3 years 4 months 4 weeks 1 day 18 hours ago) and read 7017 times:

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.


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 20, posted (3 years 4 months 4 weeks 1 day 11 hours ago) and read 6907 times:

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.

User currently offlineqblue From Canada, joined Jun 2004, 161 posts, RR: 0
Reply 21, posted (3 years 4 months 3 weeks 5 days 21 hours ago) and read 6558 times:

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?

User currently offlineViscount724 From Switzerland, joined Oct 2006, 25871 posts, RR: 22
Reply 22, posted (3 years 4 months 3 weeks 4 days 22 hours ago) and read 6407 times:

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.


User currently offlineIFIXCF6 From United States of America, joined Sep 2004, 108 posts, RR: 0
Reply 23, posted (3 years 4 months 3 weeks 4 days ago) and read 6228 times:

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


User currently offlinefriendlyskiesuk From UK - England, joined Jul 2011, 25 posts, RR: 0
Reply 24, posted (3 years 4 months 2 weeks 2 days 1 hour ago) and read 5769 times:

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



Katie
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