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Another MD11 Accident:

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Another MD11 Accident:

Old 18th Oct 2012, 22:46
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The fracture follows more or less the crown of the piston, at least initially.

Boy compression or shear, a lot of both.
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Old 18th Oct 2012, 22:51
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Further thought.

If I am correct, and it is a half hole that is visible in each broken tube, why on earth would a designer intentionally make a vent hole in the leg tube? Shirley it would be better to vent it in the closures at either end?

Secondly, had the stress chap/chapess allowed for the fact that upon rotation at take-off, the mlg carries more mass than when at rest, and hence more tension in the back of the leg because it is now angled forwards? To explain. It's possible that at rotation it is probable that the mass perceived by the back wheels is more than the total static mass of the aircraft.
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Old 18th Oct 2012, 22:56
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Shirley the truck swivels on the center axle? You are thinking the wheels are rigidly fixed at ninety degrees to strut/piston?
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Old 18th Oct 2012, 23:15
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It seems the DC-10/MD-11 family was an engineering disaster...from non-forgiving gear, leading edge devices which retract with engine failure, causing fatal stall, mis-designed cargo doors, floors which collapse which wipe out control cables, serial back-flips. How can anyone, with a straight face, say this aircraft isn't a deathtrap? Oh yes, a 'good operator' should be able to land without flight controls or leading edge slat retraction with engine failure at takeoff, right? Oops, almost forgot the center engine explosion which caused loss of all hydraulics, resulting in another fatal crash, all due to lack of a fuse (which rival L-1011 had) to protect at least one hydraulic system. The original engineers should have been jailed.

Last edited by Semaphore Sam; 18th Oct 2012 at 23:19.
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Old 18th Oct 2012, 23:27
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Responsibility for removal

Apologies if I'm being pedantic. It took 46 hours to haul the Centurion MD-11 off the runway; in that time it now appears that over 500 other Viracopos flights - pax and cargo - were directly affected; Azul (a passenger operation run by David Neely of JetBlue fame and based at Viracopos) had 15 aircraft trapped and that impacted their operations all down the line.

Viracopos is in transition, being jointly run by Infraero and the new concessionaires who take on full responsibility in January 2013. Infraero at the time were reported to have said responsibility for removal laid with the operators, Centurion. The A/C removal kit had to be hired from TAM, not sure whether brought from Sao Carlos or Sao Jose dos Campos. I don't know who paid for the TAM kit - Infraero, Centurion or their insurers - but the bottom line is it took nearly two days to get the aircraft off the runway.

My question is for the airport and cargo operators: whose responsibility is it to remove a damaged aircraft from a runway?
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Old 19th Oct 2012, 04:05
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At the risk of stating the obvious, is it not the case that the horizontal tail on this a/c is way too small, no doubt in order to save fuel.

Isn't that behind all these landing accidents?
Hi Shy Talk.

The stab of the MD11 is just fine. The stabilizer is smaller than the one on DC10, but remember the MD11 has a longer fuselage (about 11 meters if I remember correct). And all that nonsense about dynamic instability is not true either. This is usually confused with that the cruise cg is aft during cruise, and has nothing to do with instability, although it true that margins are reduced, but well within designed flight envelope.

MD11 drivers have to know what they are flying, since the design creates some points that require attention. MD11 wing has one of the highest wing loading index of civil aircraft, and this creates the need for a higher approach speed. Higher app speed gives higher decent in ft/min. When flying near Vref during approach, if the speed is allowed to decrease slightly the sink rate increases quickly. This will result in a high sink rate upon landing. A natural reaction from the pilot is to pull the yoke to arrest the sink rate. Since the main landing gear is aft of the pivot point of the aircraft, if pulling the yoke below 15-10ft, the result is that the main gear is accelerated down into the ground with an already high sink rate = kabummm!!!!

After the first landing, because the pilot is trying to arrest the flare by pulling the yoke, the pitch attitude is high, and the aircraft bounces into flight again. At this stage the MD11 is still in one peace.

The next thing is that the pilot tries to pitch down, but since the aircraft have now gone well below Vref, the stabilizer is running out of efficiency and the natural effect is that the nose pitches down as well.

Then the pilot tries to counter act this by pulling again on the yoke, and then we are back to what happen in the first place with the main gear aft of the pivot point, high sink rate, high wing loading, high rate of decent. At this stage the MD11 will impact the runway with some 2,5-3 G. Then it bounces again and the last impact will give some 4G, well beyond any civil aircraft design limits.

All this have nothing to do with design flaws or what ever people think.
The recovery is just to ad thrust to arrest the sink rate. If this happens after Bitching Betty starts to count down, then a go around must be executed.

So MD11 requires different technique. If this is not understood the MD11 is not forgiving like say the 747. Nothing to do with design flaws.


Best regards
An ex MD11 driver

Last edited by Danish Pilot; 19th Oct 2012 at 04:12.
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Old 19th Oct 2012, 04:29
  #47 (permalink)  
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Danish Pilot.


I just can't see how you can deny the MD11 design is not flawed, one accident follows another on a regular basis with this Aircraft.


No other manufacturer's widebody's have ended up on their back on numerous occasions after their wing's literally broke off.


Even the best trained, best maintained operators (LH) have had serious accidents and write offs.


What would be a hard landing on any Boeing, Lockheed or Airbus regularly turns into a catastrophe for the MD11.



It is, by any measure very unforgiving of any Pilot not performing at their best
and this describes most of us occasionally, certainly including me.

Last edited by stilton; 19th Oct 2012 at 04:30.
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Old 19th Oct 2012, 05:58
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Wink

Hi Stilton.

A Porsche 911 handles different from a Ferrari, but that doesn't mean one has a design problem over the other.

MD11 is certified to same requirement as other aircraft (Lockheed, Boeing...etc...) and does this well.

A fairly large amount of MD11 have gone upside down. You cannot land the MD11 with the same technique as you would in say a Boeing 744, and in this particular area the MD11 differs from other. But that is not design flaw.

If this is not understood and trained, then you will pay as number one on checkout to St. Peter.

A 747 cannot roll much into the wind during a crosswind landing, because the outer engines would hit the ground. This is not a design flaw, but the natural effect of the aircraft design. If this is not understood by the pilot = kabummm!
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Old 19th Oct 2012, 07:06
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Since the main landing gear is aft of the pivot point of the aircraft
I'd be interested to know what aircraft don't have the MLG aft of the C of G.
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Old 19th Oct 2012, 08:13
  #50 (permalink)  
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I cannot agree Danish Pilot.


The MD11's poor safety record speaks for itself, comparing it to differing models of sports cars is just not relevant or realistic.


It's true you will bang a pod if you land with too much wing down in a B744, but I can guarantee you the wing won't come off
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Old 19th Oct 2012, 08:28
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...in this event the CG was aft of the MLG...
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Old 19th Oct 2012, 09:44
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DouglasFlyer, that's naughty. The picture is a loading error. If you slide pallets rearwards without a tailsteady, things are going to go pear shaped!

I think Shy Talk above on this page has it. I have closely observed the MD-11 and always been convinced it is a misdesign, which for a development of a type, is appalling. There are just 2 issues in my opinion:
The horizontal tailplane is too small,
The wing should be further forward.

On final approach/slow speed, the tailplane goes severely leading edge down. I've actually been amazed at the degree I have seen. Combined with too-small an area, I suspect the pilots are running out of elevator effectiveness as the speed falls further in a bounce. I always felt no aeroplane should fly like that. The degree of slow-speed trim required shows the MD-11 wing should be quite a lot further forward. It would look 'right' too- it has always looked like an out of balance rod. See Picture

I can just imagine what DP Davies (Author 'Handling the Big Jets') who did the original British certification of the B747, would make of this monstrosity! It's safety record clearly shows it is a problem aircraft.

I would like to refer you to a previous discussion here and ManAdaSystem Post Number 19 which banged on about exactly this. An aeroplane that requires exceptional pilot skill to avoid crashing has a fatal flaw! How many times are we going to be back here discussing the same issue?

Last edited by Notso Fantastic; 19th Oct 2012 at 10:10.
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Old 19th Oct 2012, 10:42
  #53 (permalink)  

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Even the best trained, best maintained operators (LH) have had serious accidents and write offs.
Not so, American Airlines flew them MD 11s for years without crashing 'em.
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Old 19th Oct 2012, 12:14
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Stilton:
I cannot agree Danish Pilot.
The MD11's poor safety record speaks for itself, comparing it to differing models of sports cars is just not relevant or realistic.

It's true you will bang a pod if you land with too much wing down in a B744, but I can guarantee you the wing won't come off
Fair enough, no one says you have to agree. I know what is fact The point with the cars was just to point out that one thing has nothing to do with the other.

Notso Fantastic
On final approach/slow speed, the tailplane goes severely leading edge down. I've actually been amazed at the degree I have seen. Combined with too-small an area, I suspect the pilots are running out of elevator effectiveness as the speed falls further in a bounce. I always felt no aeroplane should fly like that. The degree of slow-speed trim required shows the MD-11 wing should be quite a lot further forward. It would look 'right' too- it has always looked like an out of balance rod. See Picture
An aeroplane that requires exceptional pilot skill to avoid crashing has a fatal flaw! How many times are we going to be back here discussing the same issue?
Well.... how scientific...!!

The MD11 does not require special superman skills, donīt know where you get that from. It requires knowledge and good airmanship.

Anyway, I made my point. Nothing is wrong with MD11. Take it from someone who has flown it and not just looked at pictures.....

Last edited by Danish Pilot; 19th Oct 2012 at 12:15.
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Old 19th Oct 2012, 13:12
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Everybody take a deep breath and look at the picture.

This was not a wing failure. The strut broke in shear. Totally unrelated to Narita.

The MD11F is a wonderful plane - I flew it for seven years at two companies.

She lands fast and has a glass jaw. You have to disregard the "automation pyramid" that MacDac taught and hand fly enough to keep your skills. But that's what we're paid for, right?
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Old 19th Oct 2012, 13:17
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I totally agree with Danish pilot and Huck. The MD11 is an excellent airplane I have 5,000 + hours and counting and it is the best airplane that I've ever flown. Just have to be careful and always be ahead of it, like any other airplane.
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Old 19th Oct 2012, 13:17
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I consider my abilities as a pilot as average. I flew the MD-11 for more than 8 years as a commander. She needed a high awareness from 300 feet until touchdown, but neither a hardlanding nor a bounce happened to me (even no flip over) even in adverse wind-conditions. When I did the transition to the A-330 and A-340 for the last 7 years of my career I experienced a much easier plane to land. But I also experienced a much more difficult plane to fly in gusty weather - the high wingload of the MD-11 has advantages in these conditions.
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Old 19th Oct 2012, 13:57
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Danish Pilot said,

Hi Shy Talk.

The stab of the MD11 is just fine. The stabilizer is smaller than the one on DC10, but remember the MD11 has a longer fuselage (about 11 meters if I remember correct). And all that nonsense about dynamic instability is not true either. This is usually confused with that the cruise cg is aft during cruise, and has nothing to do with instability, although it true that margins are reduced, but well within designed flight envelope.

MD11 drivers have to know what they are flying, since the design creates some points that require attention. MD11 wing has one of the highest wing loading index of civil aircraft, and this creates the need for a higher approach speed. Higher app speed gives higher decent in ft/min. When flying near Vref during approach, if the speed is allowed to decrease slightly the sink rate increases quickly. This will result in a high sink rate upon landing. A natural reaction from the pilot is to pull the yoke to arrest the sink rate. Since the main landing gear is aft of the pivot point of the aircraft, if pulling the yoke below 15-10ft, the result is that the main gear is accelerated down into the ground with an already high sink rate = kabummm!!!!

After the first landing, because the pilot is trying to arrest the flare by pulling the yoke, the pitch attitude is high, and the aircraft bounces into flight again. At this stage the MD11 is still in one peace.

The next thing is that the pilot tries to pitch down, but since the aircraft have now gone well below Vref, the stabilizer is running out of efficiency and the natural effect is that the nose pitches down as well.

Then the pilot tries to counter act this by pulling again on the yoke, and then we are back to what happen in the first place with the main gear aft of the pivot point, high sink rate, high wing loading, high rate of decent. At this stage the MD11 will impact the runway with some 2,5-3 G. Then it bounces again and the last impact will give some 4G, well beyond any civil aircraft design limits.

All this have nothing to do with design flaws or what ever people think.
The recovery is just to ad thrust to arrest the sink rate. If this happens after Bitching Betty starts to count down, then a go around must be executed.

So MD11 requires different technique. If this is not understood the MD11 is not forgiving like say the 747. Nothing to do with design flaws.


Best regards
An ex MD11 driver
Danish Pilot describes the deficiencies of the MD-11 very well.

I think we all agree that the MD-11's handling characteristics make it look like a piece of crap when compared to its more forgiving and easier to fly competitors from a pilot's point of view.

From an Airline Executive's point of view, significant shortfalls in the aircraft's performance revealed in early on-going early testing in 1991 did not endear the aircraft to the airlines which began to cancel orders.

The MD-11 certainly marked the end of the long manufacturing life of the once wonderful company, Douglas Aircraft Company which had by that time morphed into the McDonnell-Douglas Commercial Aircraft Division.
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Old 19th Oct 2012, 14:44
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This was not a wing failure. The strut broke in shear. Totally unrelated to Narita.
The only thing it may have in common is side load on a gear after several bounces and a loss of vital a/s.
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Old 19th Oct 2012, 14:54
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In Narita, the wing broke in negative, the gear strut survived. The defining data would be whether the failure load was exceeded per specification in either accident/incident....

At Heathrow, with BA038, (777), the main gear collapsed and ended in trail as the airframe skidded to a stop, as here.

The failures that cause the loss of the flight path (MD11 short final) are pilot related, and the design of the aircraft is intended to be short coupled, no one is going to move the wing, or put plugs in the Stab.....

Last edited by Lyman; 19th Oct 2012 at 14:57.
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