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Jetlagged
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RE: Technical Differences Between L-1011 And DC-10

Sun Sep 12, 2010 11:38 pm

Quoting OldAeroGuy (Reply 97):
Not really. Separating the LE/TE controls makes it more likely that the LE will be operated incorrectly. The accident report lists "Lack of any mechanism to prevent retraction of the droops at too low a speed after flap-retraction". (page 55, underlying cause 7)

You originally said the problem was the droop retraction before the flaps were retracted, thus splitting the levers was unsafe. This says "after flap retraction". Either way, the cause was the sudden change in stall AOA when the droops retracted. This would have happened had the control been combined. The basic reason for this was the captain's order to retract the droops (quite possibly with his judgement impaired by a heart attack) and the F/O's failure to check the speed (or question the command having done so). Thus procedures for the PNF to check speed before retracting flaps is much more pertinent than how the controls are designed.

Quoting OldAeroGuy (Reply 97):
"1. The dangers inherent in premature retraction of the leading-edge droops or slats are demonstrably so great that a speed-operated baulk to prevent such retraction is required and we so recommend."

Indeed, and Airbus adopted such a mechanism on the A300 too. Is there such a speed operated baulk on any contemporary Boeing design, or even some later ones? If not, then according to your argument they are all unsafe.

Quoting OldAeroGuy (Reply 97):
Much more unlikely if the LE retraction was the last detent on a common high lift system control lever. Several actions have to take place before the LE is retracted. In addition, gates on the high lift quadrant call attention to the state of the control. Typical design practice is to put the last gate at the LE retract position.

But combining the controls does not prevent the crew retracting the LE devices prematurely if no automatic system is in place to physically block control movement. All a gate can do is prevent inadvertent LE retraction. Unlike an automatic baulk, it can't prevent deliberate retraction in response to the PF's command.

Quoting OldAeroGuy (Reply 97):
Totally out of keeping with modern design practice though. Changes like this happen for a reason.

Maybe, but splitting the controls is not inherently unsafe. It's not good ergonomics, and it's an unnecessary complication, but at the time of the Trident LE devices were new and so a concensus on good design practice for their control system had not yet emerged.

Quoting OldAeroGuy (Reply 97):
Not in normal mode.

Still splittable though.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Max Q
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 1:27 am

Quoting thegeek (Reply 95):

Good point. Can I re-phrase the question then: Did the 747 require the same remediation as the DC-10 regarding floor venting? Would a collapsed floor on a 747/L-1011 have severed control lines?

Not on the 747 because, at least some of the Control lines are routed just below the ceiling
The best contribution to safety is a competent Pilot.


GGg
 
474218
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 2:08 am

Quoting Max Q (Reply 101):
Not on the 747 because, at least some of the Control lines are routed just below the ceiling


How can the "Control lines" (control cables) be routed just below the ceiling? That would make them in the cabin.

Suggest reading the following:

Quoting 474218 (Reply 96):
AD 75-15-05

MCDONNELL DOUGLAS, LOCKHEED, BOEING, AND AIRBUS INDUSTRIE McDonnell Douglas Model DC-10 Series, Lockheed Model L-1011 Series, Boeing Model B-747 Series, and Airbus Industrie Model A-300 Series Airplanes:



Note the reference to the "Boeing Model B-747 Series"

[Edited 2010-09-12 19:53:41]
 
OldAeroGuy
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 4:12 am

Quoting jetlagged (Reply 100):
You originally said the problem was the droop retraction before the flaps were retracted, thus splitting the levers was unsafe. This says "after flap retraction". Either way, the cause was the sudden change in stall AOA when the droops retracted.

An initial flap retraction was made, but trailing edge flaps were still deployed when the droops were retracted. If the TE had been completely retracted, then the crew would have ignored the TE flap retraction speeds as well. It appears rather obvious that the crew confused the LE control for the TE control and retracted the wrong device.

That's why the Accident Review had a LE retraction speed baulk as their #1 recommendation. Since the recommendation was taken up, doesn't this indicate that there was a design deficiency?

Quoting jetlagged (Reply 100):
This would have happened had the control been combined.

Highly doubtful since the high lift control would have been cycled through the various flap positions prior to the LE retraction. There would have been ample opportunities for checking retraction speeds at each position.

Quoting jetlagged (Reply 100):
Is there such a speed operated baulk on any contemporary Boeing design, or even some later ones? If not, then according to your argument they are all unsafe.

No, because none of them separate the LE control from the TE control except for non-normal conditions when crew awareness is heightened due to the abnormality of the condition.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
sfotom
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 8:34 am

The fact that the DC 10 has the ability to split the slat/ flap handle has nothing to do with the AA Chicago crash.

The DC 10 has separate cable runs for the LE (leading edge) slats and TE (trailing edge) flaps and normally they are both joined together by means of the cockpit handles connected to each other. This allows one set to be operated in the event of a cable jam or other failure of the other system.

In comparison, the 747 has only one cable run from the cockpit to the flap control valve. When the TE flaps actually extend they also provide a signal to extend the leading edge. The 747 LE and TE can also be operated independently however by use of the alternate flap system switches on the overhead panel. (I'm using the 747 as an alternate example because I'm on the road an don't have access to my L-1011 materials, I don't remember the LE/TE control path on the L-1011 and whether it also can be operated independently)

In any event, the reason the LE slats retracted on the Chicago crash is that the slat control cables for the left wing were ripped out when the engine and pylon departed the aircraft. The feature to split the cockpit slat/ flap handles was never used and the handles remained connected.
 
474218
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 1:18 pm

Quoting sfotom (Reply 104):
I don't remember the LE/TE control path on the L-1011 and whether it also can be operated independently)


On the L-1011 operation of the slats and flaps is controlled by the flap handle. Movement of the flap handle from the 0 to 4 degree detent allows the full extension of the slats. Conversely movement of the flap handle from the 4 to 0 degree detent allows full retraction of the slats.

Splitting the L-1011 flap and slat system can only be accomplished by:

1. Locking out the slats, using the slat lock switch on the FE's panel.

2. An asymmetrical condition that locks the slat or flap system down.

3. An over-speed condition that locks the slat system down.

4. A failed cable(s) after the slat programmer.

5. A mechanical or hydraulic failure in either the flap or slat drive system the prevents it from moving.

6. Manually locking the flap system with the asymmetry brake, this can only be accomplished on the ground.
 
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Jetlagged
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RE: Technical Differences Between L-1011 And DC-10

Mon Sep 13, 2010 2:50 pm

Quoting OldAeroGuy (Reply 103):
An initial flap retraction was made, but trailing edge flaps were still deployed when the droops were retracted. If the TE had been completely retracted, then the crew would have ignored the TE flap retraction speeds as well. It appears rather obvious that the crew confused the LE control for the TE control and retracted the wrong device.

Obvious is not a word which should be used like that for a supposition about an accident. Without a CVR (another report recommendation) no one can say with any certainty who ordered the droop retraction, whether speed was checked and who carried it the order. Or whether the partial flap extension, if such was the case, was a factor. Nor can you assume that the crew moved the droop lever instead of the flap lever.

The aerodynamic cause of the accident was the premature droop retraction causing immediate stall. The crew then overrode the stick pusher. This was a crew error, for whatever reason, not a design failure. The underlying cause of the accident was the pilot's heart condition and resulting incapicitation.

Quoting OldAeroGuy (Reply 103):
That's why the Accident Review had a LE retraction speed baulk as their #1 recommendation. Since the recommendation was taken up, doesn't this indicate that there was a design deficiency?

The report does not say, as far as I'm aware, that the lack of a speed baulk caused the accident. The main cause was thought to be the captains incapacitation, and the lack of any training to deal with that situation. The report assumes the Capt either ordered the droops up or moved them himself. It also says that the aircraft was carrying out noise abatement procedures (flaps fully up, thrust reduced), and had been for some 21 seconds until the droops were retracted. So that says to me (I don't have a copy of the actual report) that the TE flaps were already retracted. Also speed was below schedule for the noise procedure (163 kts, not 177 kts) indicating the capain was not properly concentrating and so not maintaining the correct climb speed or configuration.

There already was a mechanical droop lever baulk, which was manually operated by the crew. A speed controlled baulk may have prevented the accident, but lack of one didn't cause it.

Quoting OldAeroGuy (Reply 103):
Highly doubtful since the high lift control would have been cycled through the various flap positions prior to the LE retraction. There would have been ample opportunities for checking retraction speeds at each position.

It's still possible to retract slats prematurely though. In this accident procedures weren't being followed closely. Flight crew were far more lax in procedures in those days too, compared to today.

Quoting OldAeroGuy (Reply 103):
No, because none of them separate the LE control from the TE control except for non-normal conditions when crew awareness is heightened due to the abnormality of the condition.

Yet Airbus considered it necessary to include a speed baulk on the A300B, which uses a single lever. The fact is that if the PF orders flaps up and the F/O complies without a speed check then this accident could happen in a contemporary Boeing design too, such as the 727 or 737-200.

Apart from droop baulks the report recommended CVRs and better follow up of previous similar incidents (in an echo of the THY DC-10). IIRC the screening of pilots with ECG at medicals was also a result of this accident.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
OldAeroGuy
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RE: Technical Differences Between L-1011 And DC-10

Tue Sep 14, 2010 4:13 am

Quoting jetlagged (Reply 106):
The report does not say, as far as I'm aware, that the lack of a speed baulk caused the accident.

I've given you a link to the accident report and a quote of the report statement on an underlying cause of the accident. You can read it yourself from the report.

Quoting OldAeroGuy (Reply 97):
The accident report lists "Lack of any mechanism to prevent retraction of the droops at too low a speed after flap-retraction". (page 55, underlying cause 7)

http://www.aaib.gov.uk/cms_resources...I.pdf
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
Max Q
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RE: Technical Differences Between L-1011 And DC-10

Wed Sep 15, 2010 3:28 am

Quoting 474218 (Reply 102):
How can the "Control lines" (control cables) be routed just below the ceiling? That would make them in the cabin.

You are correct, that was not the best description.



'Above the Passenger ceiling' is a better one and is what I meant.
The best contribution to safety is a competent Pilot.


GGg
 
411A
Posts: 1788
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RE: Technical Differences Between L-1011 And DC-10

Wed Sep 15, 2010 8:05 pm

***I know this caused a few performance issues, in that the L1011 had to be rolling at a fair old whack before they could apply full power to the number 2,***
Sorry, not true, except on the -500 model, with significant surface cross winds present, upon takeoff.

One wonders, just where do to some folks get this total misinformation?

And further, one poster incorrectly stated that the engines on the -200 model were the same as the -500 model.
ALSO, totally incorrect.
-200 model....RB.211-524B02 engines.
-500 model, RB.211-524B402 engines.
Quite a large difference in achieved performance.

With some folks, FACTS are hard to understand.
No surprise.
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Technical Differences Between L-1011 And DC-10

Wed Sep 15, 2010 10:51 pm

Quoting 411A (Reply 109):
And further, one poster incorrectly stated that the engines on the -200 model were the same as the -500 model.
ALSO, totally incorrect.
-200 model....RB.211-524B02 engines.
-500 model, RB.211-524B402 engines.
Quite a large difference in achieved performance.

Not according to the T.C.D.S.

The following engines are approved for use on the L-1011-385-1-15 (L-1011-200)

3 Rolls-Royce RB.211-524B-02 engines
or
3 Rolls-Royce RB.211-524B3-02 engines
or
3 Rolls-Royce RB.211-524B4-02 engines
or
3 Rolls-Royce RB.211-524B4-D-02 engines

The following engines are approved for use on the L-1011-385-3 (L-1011-500)

3 Rolls-Royce RB.211-524B-02 engines
or
3 Rolls-Royce RB.211-524B3-02 engines
or
3 Rolls-Royce RB.211-524B4-02 engines
or
3 Rolls-Royce RB.211-524B4-D-02 engines

So all L-1011 approved RB-211-524 subtypes could be used on either the -200 or -500.

Specific performance data for each engine subtype was provided in the AFM.

Additionally Lockheed could provide a Service Bulletin that would allow inter-mixing the different engines sub types.
 
411A
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RE: Technical Differences Between L-1011 And DC-10

Thu Sep 16, 2010 12:50 am

Quoting 474218 (Reply 110):
Additionally Lockheed could provide a Service Bulletin that would allow inter-mixing the different engines sub types.

Quite a large difference between approved, and what was done in actual airline service, with 'as delivered' airplanes.
NO -200 airplanes were delivered with RB.211-524B402 engines, just as one example.
Intermix notwithstanding.
And further, in order to actually install an RB.211-524B402 engine on a -200 model, in the number two engine position, requires modification of the engine adaptor ring.

Just the facts.
 
epten
Posts: 194
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RE: Technical Differences Between L-1011 And DC-10

Thu Sep 16, 2010 9:48 am

Quoting AirframeAS (Reply 12):
If someone were to tell me that, my rebuttal would be "If it (L-1011) was more technically advanced, then why did the DC-10 outsell the L-1011?"

This is a classic exaple of an invalid argument (appeal to popularity).

Is Madonna the best, technically most developed singer with greatest vocal range? She sure sold more albums than any other female singer.

[Edited 2010-09-16 02:48:33]
 
474218
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RE: Technical Differences Between L-1011 And DC-10

Thu Sep 16, 2010 1:15 pm

Quoting 411A (Reply 111):
NO -200 airplanes were delivered with RB.211-524B402 engines, just as one example.


I will have to dig out my "as delivered list" but I am almost positive the at a minimum the two British Air Tours -200 (s/n 1211/1212) were equipped with B4-02 engines.
 
TrijetsRMissed
Posts: 1983
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RE: Technical Differences Between L-1011 And DC-10

Sat Sep 18, 2010 11:19 pm

Quoting sfotom (Reply 98):
Following the AA crash, a number of AA aircraft were found with cracks in the same area and pattern as the lost aircraft, they did not find any of these cracks on the united aircraft, or on any other DC 10s that did not use "forklift from the side" method of engine change.

Cracks were found on AA, UA, and CO aircraft. Crane or forklift - it didn't matter. NW did not remove the engine and pylon together, and hence never were impacted by this issue. (Temp grounding notwithstanding)
There's nothing quite like a trijet.
 
b741
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RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 3:33 am

According to a 1978 publication, the DC-10 had the most technologically advanced flight-deck at the time.
Being Bilingual, I Speak English And Aviation
 
411A
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Joined: Mon Nov 12, 2001 10:34 am

RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 3:39 am

Quoting 474218 (Reply 113):
1212

I've flown s/n 1212 extensively in the past...-524B02 engines installed, in all three positions.
 
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Starlionblue
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RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 4:14 am

Quoting b741 (Reply 115):
According to a 1978 publication, the DC-10 had the most technologically advanced flight-deck at the time.

That's a fairly vague statement and could well just have been regurgitation of McDonnell Douglas marketing. What was the publication?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 7:45 am

Quoting 474218 (Reply 17):
Back in the 1970 there was a saying that was going around: The perfect airliner would be:

1. Designed by Lockheed

2. Built by Boeing

3. Sold my Douglas

   I like that!!!!!!

Quoting Pihero (Reply 25):
What we could say, as a fact, is that the Tristar was designed from it's start as a"system", built around the first civilian integrated avionics, and that's constitutes the very difference between both tri-jets.

Very much agree. IMHO, it was very much ahead of its time. The flight control AFDS schematic that 474218 posted in the runaway stabilizer trim showed it... Was the first computer-intervened/optimized (albeit not FBW) flight control system of any jetliner? The next jetline that had this was the 320 if I remember correctly...

Quoting Pihero (Reply 25):
In many ways, looking at Airbus architectures -especially the hydraulics - is seeing the heritage of the "Tripod". (Before the 380, that is ...)

I think it goes beyond just the HYDs. The FBW architecture also digitized the stabilizer commands, similar to the flying stabilizer of the Tristar.

Quoting thegeek (Reply 40):
Which actually was a similar situation to the one in Brazil,

I think it is different. The TAM case had 1 thrust lever still in climb/ A/T detent. AFAIK, the LH accident in Poland was attributed to poor crew action and poor information received regarding the wind conditions (they ended up landing on a wet runway with a 20kt tailwind).

Quoting MD-90 (Reply 45):
3. 386 DC-10s built compared to 250 L-1011s shows that Douglas sold 64% more DC-10s, which is a pretty commanding lead but the fact is neither company made money on their respective programs overall, although Douglas again had a big leg up with the 60 aircraft KC-10 gift from the government thrown to a grumpy McDonnell.
Quoting jetlagged (Reply 56):
The Hindenburg did not crash due to a design flaw.

Putting a flammable skin on a body filled with flammable gas isn't? The Hindenburg is the same as a petrol station allowing smokers to walk next to the pumps filling a car.

Quoting jetlagged (Reply 56):
MD-80 series

The Lion Air accident in SOC/WARQ is "suspect" on this issue. Having being informed of discussions with the surviving crewmember and accident investigators and FDR data (not sure if those details ended up in the final report or not), but the spoilers retracted and did not deploy again despite the speedbrake handle being in the deployed position. However, this is suspect only, and that even without that problem, the aircraft was likely to have ended up with a runway excursion regardless.

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
b741
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RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 5:25 pm

Sorry, my mistake. The publication stated that the DC10 was the most advanced flight-deck illustrated in the book. They go on to state that the Tristar and A300B are more advanced. I might have thought the A300 less advanced.
Being Bilingual, I Speak English And Aviation
 
411A
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RE: Technical Differences Between L-1011 And DC-10

Tue Sep 21, 2010 7:01 pm

Quoting b741 (Reply 119):
I might have thought the A300 less advanced.

It was, without a doubt.
A comprehensive study of the various aircraft systems redundancy features, would tell the tale.
Do NOT be deceived by FD appearances.
IE: Beauty is a lot more than skin deep.
 
thegeek
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RE: Technical Differences Between L-1011 And DC-10

Wed Sep 22, 2010 3:19 am

Quoting mandala499 (Reply 118):
The TAM case had 1 thrust lever still in climb/ A/T detent. AFAIK, the LH accident in Poland was attributed to poor crew action and poor information received regarding the wind conditions

Ok, but leaving the thrust level in climb was a "poor crew action" in retrospect. Also the computer didn't give any more "information" than "retard, retard", which didn't make it clear what the consequences of not doing so were. Although if the crew had listened to the computer everyone probably would have lived.
 
mandala499
Posts: 6600
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RE: Technical Differences Between L-1011 And DC-10

Wed Sep 22, 2010 6:23 am

Quoting thegeek (Reply 121):
Ok, but leaving the thrust level in climb was a "poor crew action" in retrospect.

Retrospect or not... it was definitely "poor crew action", the problem is... why did it happen? One locked (dispatched as such) reverser may have resulted the crew being confused with the old procedure which was both thrust levers to idle, and then only reverse on the one with the good reverser. That procedure, if I remember correctly, was already changed into both levers to idle and both into reverse despite only having 1 good reverser... The change was to prevent confusion in the sequence of events in the high workload of a landing. Unfortunately, the TAM accident proved the danger of the previous version of the procedure. Some companies have gone further to dictate manual thrust only for non-autolands (but that is probably based on their experience from previous non-FBW aircraft).

Quoting thegeek (Reply 121):
Also the computer didn't give any more "information" than "retard, retard", which didn't make it clear what the consequences of not doing so were.

The automated voice "retard" is a reminder and not a command. One idles the throttles on landing, chop it to idle or smoothly reduce to idle, but be idle upon touchdown.... Be you in a Boeing or Airbus, MD, Lockheed (just to keep it within the topic)...

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !

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