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Starlionblue
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 1:36 am

Quoting 777WT (Reply 48):
In a report related to this, they showed an image of the AA's A300 rudder which has a layer of composite or metal added to both sides of it and, holes were drilled and multiple bolts were installed.

This was traced back to the building of the AA's A300. In the hanger, there was a storm outside and the plane's tail hit the ground during the storm. Airbus looked at the rudder and saw damage, they decided to fix it instead of replacing the whole thing.

They didn't put it in the log and didn't tell AA about this. Surely AA would have rejected the aircraft if they did tell them.

That's one thing should be looked at too.

Probably it should be looked at, but things like this happen all the time. You can't assume the rudder was less than sound just because it had been repaired. Aircraft components are repaired constantly.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
philb
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 1:46 am

Quoting 777WT (Reply 48):
In a report related to this,

Your source?

Quoting 777WT (Reply 48):
This was traced back to the building of the AA's A300. In the hanger, there was a storm outside and the plane's tail hit the ground during the storm. Airbus looked at the rudder and saw damage, they decided to fix it instead of replacing the whole thing.

They didn't put it in the log and didn't tell AA about this. Surely AA would have rejected the aircraft if they did tell them.

Hope you can prove that. You are promulgating a sourceless statement that a multinational manufacturer carried out a procedure that could, prima facie, have been considered by some unsafe and you have linked it to an accident that claimed the lives of passengers and crew and, not only did they do that, but hid their actions.

Wow, heady stuff. I hope you have impeccable sources or an excellent lawyer.
 
redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 1:50 am

Quoting Scorpio (Reply 45):
Yes. Once. Not repeatedly as happened on AA587. Finnwings stated it correctly in reply 42:

Sorry, in all my flight training and in all the manuals I have, no where does it state that an abrupt movement means ONE movement. Indeed, I just checked with the CFI who did my BFR a few months ago and he stated the rule still applies for Va.

My point was that pilots have always been taught that abrupt control inputs will not damage an airplane as long as it's below Va. Granted, since AA587, everyone is taking a second look at this basic tenet but, to my earlier point, pilots, including the first office of AA587, were ingrained with the belief that abrupt movement below Va will not damage a plane. That is the very reason AA stipulated in its flight manuals that aggressive inputs were standard OP for keeping the aircraft under control (if below Va).

Quoting Starlionblue (Reply 47):
You can break a plane at speeds below Va with control inputs.



Yes, you can, as was proven by AA587. However, if it can be done then it is a sign that the Va limitations are not accurate for that aircraft type. Va is intended to identify for a pilot a LIMITING speed - the maximum speed at which the pilot can make abrupt control movements. If you can break the plane below Va then that simply means the Va is not accurate and, more importantly, does not serve the purpose for which it is indicated.

Quoting Starlionblue (Reply 47):
But you can break a plane at speeds below Va with control inputs. Just make repeated inputs to the stops in opposite directions. It's that simple.

Obviously that statement is true for a 300. I don't think you can apply such a blanket statement to any aircraft.

Quoting 777WT (Reply 48):
This was traced back to the building of the AA's A300. In the hanger, there was a storm outside and the plane's tail hit the ground during the storm. Airbus looked at the rudder and saw damage, they decided to fix it instead of replacing the whole thing.

Sorry, but that is not entirely accurate. The plane that fell back on its tail was determined not to have been the 300 involved in AA587. The plane you referenced was traced to it's owner (AA?) and inspected and found to be in good order so whatever repairs Airbus effected at the plant were in fact sturdy and sound.
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coa747
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 2:00 am

Because a determination can no be made as to whether the rudder movements occurred as a result of pilot inputs or as a result of the rudder fluttering as it began to unhinge it seems all the more reason to further investigate the issue. I too can not see that Airbus response to the un-commanded rudder issues to be sufficient. The design should have been more closely scrutinized following these reports. Movement of the rudder pedals cannot automatically infer that the pilot made those inputs. The possibility exists that the inputs were made but exaggerated by the flight control system which is documented to have had issues the day of flight. The flight control system was reset prior to departure to clear a pitch trim issue as noted in the logbook.
 
mrocktor
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 2:38 am

Quoting RedFlyer (Reply 38):
Not true, you should not be able to "break" a plane as long as it's speed is maintained below Va (design maneuvering speed).

Yes you can. Regulations assume that certain extreme inputs are performed (as in a "rudder kick"). They do not intend to make the aircraft immune to every possible pilot input.

Quoting NAV20 (Reply 41):
it produces rudder 'feel' that is the direct opposite of what all pilots will have grown used to from their first flying lesson

Spot on, the rudder becomes more sensitive to a pedal input instead of less, and the variable stop does nothing to mitigate this (as it only affects maximum deflection, not the dynamics of deflection within the available range). I believe this is the main contributing cause to the accident, and an expensive lesson learned.

Quoting RedFlyer (Reply 43):
Sorry, wrong. Va, which goes down as a plane's weight goes down, represents the maximum speed at which you can use FULL, ABRUPT control movement without stressing the airframe.

You can use FULL ABRUPT control movement. Just not repeatedly, read what he said - he's right.

Quoting Coa747 (Reply 53):
Movement of the rudder pedals cannot automatically infer that the pilot made those inputs.

Although the system is hydromechanic, that does not mean there is mechanical feedback of a rudder deflection to the pedals. I don't know if there is on the A300 and I'd venture the guess that you don't know either.

Quoting Coa747 (Reply 53):
The flight control system was reset prior to departure to clear a pitch trim issue as noted in the logbook.

Completely irrelevant to the rudder system, as far as I know.

mrocktor
 
redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 3:05 am

Quoting Mrocktor (Reply 54):
You can use FULL ABRUPT control movement. Just not repeatedly, read what he said - he's right.

Ok, fair enough - being that your profile says you're an aeronautical engineer, I will have to defer to your expertise. So that begs the question: what constitutes "repeatedly"? One full movement in one direction and another back in the opposite direction? Two full movements in either direction? Three? More?

Also, if your assertion is considered standard knowledge, there's a whole cadre of pilots and engineers out there that need to be "retrained" in that line of thinking. After all, until recently AA itself didn't think that aggressive control movement below Va would prove deleterious to an airframe. Hence their published OP for regaining control of an aircraft through "aggressive use of rudder inputs."
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777236ER
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 3:23 am

Quoting RedFlyer (Reply 43):
Sorry, wrong. Va, which goes down as a plane's weight goes down, represents the maximum speed at which you can use FULL, ABRUPT control movement without stressing the airframe.

Sorry, wrong. Full abrupt control movement (ie. manoeuvres...), just not repeated movement. Read what I wrote.
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redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 4:46 am

Quoting 777236ER (Reply 56):
Sorry, wrong. Full abrupt control movement (ie. manoeuvres...), just not repeated movement. Read what I wrote.

And as I asked Mrocktor, what constitutes "repeated" movement?

Keep in mind, if a pilot needs to make an abrupt control change - for whatever reason - that abrupt control change will in all likelihood put the aircraft into an attitude that is not desirable nor maintainable. Therefore, the pilot will need to make, at a minimum, a counter - and equally abrupt -maneuver to put the aircraft back into a normal flight envelope.

So, again, what constitutes "repeated" movement? Can someone define it?

Certainly if one does abrupt, and extreme control movements repeatedly without stopping the airframe will eventually fail, but that should not occur after after just a few movements and, more importantly, under circumstances expected to be encountered in a service (as opposed to a test) flight.

While the co-pilot of AA587 made several abrupt rudder inputs, I don't think anyone honestly believes they were beyond what could be expected to happen at some point in an airliner's service life. Perhaps the inputs were excessive for that particular situation AA587 encountered but no one can say two full rudder swings over the span of a few seconds would be deleterious to the integrity of the airframe.
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777wt
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 5:20 am

It was in reference to this photo:
http://www.ntsb.gov/events/2001/AA587/AA587_15.jpg

Look at the bottom of this page, all of them are rudder attachments.
http://www.ntsb.gov/events/2001/AA587/tailcomp.htm

Related info:http://www.iasa.com.au/folders/Safety_Issues/others/aa587/images/vertfin.gif

And the storm story with the plane, it's not the exact one I read but couldn't find the article which had this photo in it with the story.

Quote:

Related Quote
AMR 22.30 unch.
delayed 20 mins - disclaimer
Quote Data provided by Reuters



Wednesday January 2, 5:42 am Eastern Time
Airbus says no record that NY jet damaged in storm
(UPDATE: Rewrites with Airbus comment, changes dateline from WASHINGTON)

PARIS, Jan 2 (Reuters) - European plane maker Airbus has no record that the A300 jet that crashed moments after taking off in New York last November was damaged in a storm before it was delivered to American Airlines (NYSE:AMR - news), an Airbus spokeswoman said on Wednesday.

The spokeswoman was responding to questions following a report in the Washington Post which said investigators were looking into evidence that the plane in question had been blown backwards onto its tail during a violent storm in 1987 while awaiting final work at an Airbus factory.

``There is no record in the papers of the plane of something like that,'' an Airbus spokeswoman told Reuters. ``Under normal circumstances, there would be a repair indicated.''

Citing unidentified sources close to the investigation, the Post said the plane was carefully inspected after the storm and no damage was found.

The newspaper said there was no indication the alleged incident had anything to do with the November crash, but investigators looking into the crash that killed 260 on board and five people on the ground said they could not overlook the incident.

U.S. investigators have not determined the cause of the crash but have focused on the composite makeup of the tail section of the A300-600 series and extreme rudder movements just after the aircraft passed through a relatively common bout of turbulence from a bigger plane flying several miles ahead.

Investigators believe the A300's vertical stabilizer, or tail fin, and its rudder fell off before American Airlines flight 587 crashed 103 seconds after taking off from New York's John F. Kennedy Airport bound for Santo Domingo, Dominican Republic.

American Airlines is owned by AMR Corp. Airbus, based in Toulouse, France, is owned by European Aeronautic, Defense & Space Co. and BAE Systems Plc (quote from Yahoo! UK & Ireland: BA.L).

From: http://www.dr1.com/forums/archive/index.php/t-15018.html

Quoting Philb (Reply 51):
Your source?


Hope you can prove that. You are promulgating a sourceless statement that a multinational manufacturer carried out a procedure that could, prima facie, have been considered by some unsafe and you have linked it to an accident that claimed the lives of passengers and crew and, not only did they do that, but hid their actions.

Wow, heady stuff. I hope you have impeccable sources or an excellent lawyer.
 
777236ER
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 5:25 am

Quoting RedFlyer (Reply 57):

So, again, what constitutes "repeated" movement? Can someone define it?

Full movement one-way, followed by full-movement the other way is certified. The manoeuvring speed is for manoeuvres - none of which require repeated significant rudder input.

Quoting RedFlyer (Reply 57):



While the co-pilot of AA587 made several abrupt rudder inputs, I don't think anyone honestly believes they were beyond what could be expected to happen at some point in an airliner's service life.

Other airline pilots did, other airlines did, aviation authorities did, the manufacturers did.

The rudder is not to be used in flight, other than for approach and low speed climb out. Simple as.

Quoting RedFlyer (Reply 57):
but no one can say two full rudder swings over the span of a few seconds would be deleterious to the integrity of the airframe.

Yes it can. The PF made three stop-to-stop rudder reversals, that's left-right-left-right-left-right. It was against his training, manufacturer recommendations, FAA-approved manuals and training. It was pilot error.

Quoting 777236ER (Reply 56):
After all, until recently AA itself didn't think that aggressive control movement below Va would prove deleterious to an airframe. Hence their published OP for regaining control of an aircraft through "aggressive use of rudder inputs."

The NTSB (who I, as every flier in the world should, trust) say rudder input is not trained for recovery of a clean aircraft.
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redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 5:52 am

Quoting 777236ER (Reply 59):
Other airline pilots did

Is that why there was a chorus of pilots that protested the results of the NTSB?

Quoting 777236ER (Reply 59):
other airlines did

Operating procedures are known to vary from airline to airline. That doesn't mean one is right nor the other wrong.

Quoting 777236ER (Reply 59):
aviation authorities did

Sorry, but I believe operating procedures for a particular aircraft type go through a review process by the local aviation authority, which in this case was the FAA. I don't believe airlines can publish OP at their whim.
A government big enough to take away a constitutionally guaranteed right is a government big enough to take away any guaranteed right. A government big enough to give you everything you need is a government big enough to take away everything you have.
 
777236ER
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 6:05 am

Quoting RedFlyer (Reply 60):

Is that why there was a chorus of pilots that protested the results of the NTSB?

Notice how that chorus comes from either AA, or unions.

Quoting RedFlyer (Reply 60):
Sorry, but I believe operating procedures for a particular aircraft type go through a review process by the local aviation authority, which in this case was the FAA. I don't believe airlines can publish OP at their whim.

The FAA can't be expected to scrutinise every single aspect of AA's training. The NTSB found AA training didn't emphasis the non-use of rudder at altitude, although it did touch on it.

The crash was primarily pilot error, end of story.
Your bone's got a little machine
 
GPHOTO
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 6:40 am

Pilot Error is a very emotive term and certainly seems to have stirred up some of the posters here. It is that emotiveness that causes many of the problems with public interpretation of airliner accidents. In order to fully understand what happens in an accident, you need to leave that emotiveness behind.

Too many people assume that Pilot Error means that the pilot was an idiot, incompetent or should never have been in the cockpit. However, it means what it says, that the pilot made an error. Its a very blunt and often harsh term and having read a number of accident investigations, I can almost always feel a great deal of sympathy for the pilot involved.

It may be because the pilot WAS an idiot, incompetent or should never have been cockpit - but I can't immediately recall any Pilot Error accidents where this was so. In the vast majority of cases, a perfectly competent pilot, maybe even a highly experienced one with a perfect record and full marks in all his assessments can be caught out by a situation rapidly getting out of control. Sometimes events happen too fast for a correct analysis by the pilot - we always have the benefit of hindsight when talking about incidents here and plenty of time to digest the information we get. We also have the luxury of having information not available to the pilot at the time. All these things give us a clearer picture than the pilots can have and sufficient time to make the right decision.

Pilot Error causes more airliner accidents (the figures are worse for non-airliner air accidents) than anything else. There are many sources of information for this,
see here for one.

I have every faith in airline pilots. Airliner flying is one the most professional, well controlled and safe operations that human beings have ever conducted, but every now and then, even the best can make a slip, a mistake, misjudge a situation or do something inexplicable that they would never normally do. And sometimes, very rarely, that can bring a plane down.

Don't be afraid to accept the Pilot Error verdict for any incident where it has been found to be involved. Accept what it truly means, not what your heart thinks it means and do not judge them harshly.

Regards,

Jim
Erm, is this thing on?
 
GPHOTO
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 6:53 am

Quoting Newark777 (Reply 2):
It's always easier to just blame the dead pilot after the fact.

Or the surviving pilot. Fact is, most accidents ARE caused by pilot error.

There have been cases of pilots being unfairly blacked - the Manchester United disaster is considered to be one such case. See here for more information.

Best regards,

Jim
Erm, is this thing on?
 
philb
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 6:55 am

777WT,

The quote from Reuters you have posted confirms that there was no record of the aircraft involved in the accident having suffered the damage you state in your original post. It certainly does not say that the incident was covered up as you so strongly state:

Quoting 777WT (Reply 48):
They didn't put it in the log and didn't tell AA about this. Surely AA would have rejected the aircraft if they did tell them.

...and the piece does say that the NTSB could not overlook the (alleged) incident:

Quoting 777WT (Reply 58):
The newspaper said there was no indication the alleged incident had anything to do with the November crash, but investigators looking into the crash that killed 260 on board and five people on the ground said they could not overlook the incident.

Obviously they checked it out and found no reason to link the two events.

So why do you think that the storyshould be checked out again now and where do yo get the idea of an Airbus cover up?
 
redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 8:09 am

Quoting 777236ER (Reply 61):
The crash was primarily pilot error, end of story.

I hardly think it's the "end of [the] story." Given past investigations of the NTSB which were re-opened (the UA 747 that blew a cargo door over the Pacific comes to mind) after being petitioned by various interested parties, I think that's a pretty arrogant attitude. Besides, who are you to claim "end of story"? That's just your opinion. If you think it's end of story then read another thread and don't annoy those of us who would like to analyze the events further.

Best regards,
A government big enough to take away a constitutionally guaranteed right is a government big enough to take away any guaranteed right. A government big enough to give you everything you need is a government big enough to take away everything you have.
 
HPnonrev99
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 9:02 am

Quoting Coa747 (Thread starter):
As a grad student enrolled in the Safety Science program at Embry-Riddle, who hopes to go to work for the NTSB after graduation

If you want to go work for the NTSB, I don't think publishing an article where you "doubt the boards findings" is a good way to get your foot in the door!!
Coming soon to an airport near you.
 
HPnonrev99
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 9:25 am

Quoting Coa747 (Reply 32):
You can not tell me that flight control issues on the A300 were not serious before the 587 crash as I have proved their were

You cited 3 incidents over 17 years. Hardly proves anything!

Quoting Coa747 (Reply 53):
The flight control system was reset prior to departure to clear a pitch trim issue as noted in the logbook.

The ELAC (pitch trim computer as you call it) has nothing to do with the rudder. You should get to know your Airbus systems a little better before biting off more than you can chew.
Coming soon to an airport near you.
 
aeroweanie
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 10:12 am

 
redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 10:24 am

Quoting 777236ER (Reply 61):
Notice how that chorus comes from either AA, or unions.

While I'll agree that AA and it's union have been the most vocal, I've spoken to a number of commercial airline pilots from different airlines, as well as pilots at the local airport that I fly my plane from, that were stunned by the findings. While they all agree that they weren't sure of the benefits of agressive rudder inputs in the upset encountered by AA587, they were, to a person, shocked that the vertical stab would separate.

Quoting 777236ER (Reply 59):
The PF made three stop-to-stop rudder reversals, that's left-right-left-right-left-right.

And how do you know the airframe integrity breach did not occur after the FIRST rudder swing (which we all agree should be tolerable) with the resulting two swings simply contributing to the vertical stabilizer separation?
A government big enough to take away a constitutionally guaranteed right is a government big enough to take away any guaranteed right. A government big enough to give you everything you need is a government big enough to take away everything you have.
 
redflyer
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 11:28 am

Quoting HPnonrev99 (Reply 66):
If you want to go work for the NTSB, I don't think publishing an article where you "doubt the boards findings" is a good way to get your foot in the door!!

Why is that? Solid and irrefutable scientific analysis is contingent upon proving or disproving alternate theories and facts. And not necessarily at the same time. In the absence of any other hard facts, the NTSB went with the most plausible explanation. That is not to say that its findings cannot be reversed at a future date and with the presentment of additional information.

Your logic implies that to obtain entry into the NTSB, Coa747 has to agree with everything they say. "Herd" mentality is not conducive to obtaining the objective - one need only look at what a "herd" mentality resulted in with the two shuttle disasters endured by NASA.
A government big enough to take away a constitutionally guaranteed right is a government big enough to take away any guaranteed right. A government big enough to give you everything you need is a government big enough to take away everything you have.
 
MissedApproach
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 11:47 am

Quoting Coa747 (Thread starter):
mechanics trouble-shooting an A300's rudder problem found composite delamination and a bent rudder control rod.



Quoting Coa747 (Thread starter):
What happens over 13 years of 14,934 cycles and 37,550 flight hours when a composite fin is subjected to in-flight turbulence at different altitudes after a heat or cold soak with possible long-term moisture intrusion.

I asked something along these lines in a thread after the AA587 report was released. While composites aren't really all that new to aviation, I don't believe the behavior of composites is understood nearly as well as metallurgy.

Quoting Starrion (Reply 5):
Has any more information regarding the Air Transat A300 the had the rudder disintergrate on departure from Havana been released?

As mentioned this was an A310, but aren't some structures the same as the A300? I thought the empennage & fuse cross section were the same. Anyway, the investigation is still in progress, the most recent update can be found here: http://www.tsb.gc.ca/en/reports/air/2005/index.asp
Can you hear me now?
 
aeroweanie
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 2:11 pm

Quoting Coa747 (Thread starter):
5. Airbus parameters for stress-testing its composite fins were not realistic given the real world operating conditions of the aircraft. The tests were carried out at a constant ground temperature of 70 degrees C and 70% humidity while American Airlines A300's routinely experienced temperature shifts of 83 degrees C from the ramp at Miami to altitude and a humidity swing of 80% or more. Composite structures become brittle when cold and soft when heated. What happens over 13 years of 14,934 cycles and 37,550 flight hours when a composite fin is subjected to in-flight turbulence at different altitudes after a heat or cold soak with possible long-term moisture intrusion.

This is nice conjecture, but had nothing to do with the failure. If you look at the FAA presentation I linked to in reply 68, you will find the tail failed at more than 150% of limit load. Hence, the tail was overdesigned.

What the FAA presentation shows is that the pilot made rudder inputs at a frequency that coupled with the aircraft's dutch roll mode. This caused the overswings to be greater than the normal max yaw angle of the aircraft, resulting in abnormally high loads on the tail. The tail then failed, past its design ultimate load (150% of limit load).

As the FAA presentation notes, the A300-600 rudder is unusually sensitive, due to the design legacy where the A310 rear fuselage and tail was combined with the A300B4 to create the A300-600.
 
NAV20
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 3:09 pm

Quoting GPHOTO (Reply 63):
Fact is, most accidents ARE caused by pilot error.

That's a pretty drastic over-simplification, GPPHOTO. Suppose you're driving a car in snow and ice, and you skid and have an accident? There's an element of 'driver error' in that - for a start, you decided to get out of bed that morning; then you decided to go driving; and if you'd kept your speed down to 5 mph all the way, you probably wouldn't have skidded at all....

Virtually all aircraft accidents are the result of a 'cascade' of events, which COMBINE to produce the accident. And that is exactly what the NTSB concluded; three main causes, pilot error, Airbus rudder systems, and AA training. Three additional possible contributing causes that it didn't mention in its final conclusions were the level of departure separation allowed by the ATC controllers at Kennedy, the fact that the controller actually directed both the previous JA flight and AA587 on exactly the same course on climb-out, heading straight for the George Washington Bridge ("Fly the Bridge Climb.."), and of course the turbulence itself.

Beyond that, you have to look at the role of organisations like the NTSB. It is not to apportion blame; it is to analyse the causes of an accident and (as its name implies) make recommendations to increase future safety. And it wouldn't be practical for it to cause the whole industry to grind to a halt - by grounding whole marques of aircraft until they have been modified, stopping entire airlines from operating until they have retrained their pilots, closing whole airports until they have re-jigged their ATC arrangements. Or to destroy public confidence by indicating that all these matters probably played a part. So a conclusion that the 'main cause' was 'pilot error' suits pretty well everyone - except, of course, the pilot, but he/she is usually dead and past caring.

As aeroplanes get more complicated, there's an additional factor creeping in now; that the pilot is supposed to understand the way the various systems work, and in what circumstances they may overrule his commands; as well as the structural limits of each aeroplane type. Suppose Sten Molin had survived, to undergo hours of cross-examination by three or four sets of hungry lawyers?

"So, Mr. Molin, you applied left rudder. Why?"

"The plane was banking sharply to the right, the nose was dropping, and I could feel a sideslip, and that the aircraft was losing more height. I also pulled the column back, applied left yoke to try to level the wings, and called for full power."

"Please could we just concentrate on the rudder movements for the moment; those are what we are examining at the moment? Now, less than two seconds later, you applied RIGHT rudder - why?"

"The turbulence had caused the aircraft to begin rolling the other way, to the left. So I reversed the rudder - not just the rudder, all the flying controls....."

"Please concentrate on the rudder. Were you aware at this time that the manufacturer had recommended that abrupt movements of the rudder were to be avoided in conditions of turbulence?"

"I'd heard something about that. But this was an emergency, we were losing height fast, the aircraft was in danger. I suppose.....er....I suppose I had to disregard that......"

"I SEE, Mr. Molin - you CHOSE to disregard the manufacturer's safety recommendations? Is that what you're saying.....?


[Edited 2005-08-25 08:23:58]
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
GPHOTO
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RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 4:10 pm

Quoting NAV20 (Reply 73):
That's a pretty drastic over-simplification, GPPHOTO.

Oh, I agree with you. What I am trying to say is that people should be more understanding of what the term Pilot Error means, people attach too emotive an interpretation. It means the pilot did something which was a factor in the incident. There are posters here who are trying to say the pilot did nothing wrong, its all the fault of Airbus, blah, blah, blah. This is wrong.

The pilot will have had reasons why he did what he did and would NOT have acted that way if he thought for one moment he was putting his aircraft, its passengers or crew in danger. But his rudder actions overstressed the airframe beyond it's limits and it broke.

Quoting NAV20 (Reply 73):
"I'd heard something about that. But this was an emergency, we were losing height fast, the aircraft was in danger. I suppose.....er....I suppose I had to disregard that......"

This was my favourite line of your post. I know its hypothetical, but its a good example of what I am trying to get at, obviously not very well. The pilot will have performed those actions for what he felt were good reasons at the time, he will have been trying to control the aircraft appropriately (as he felt). Unfortunately, those actions damaged the aircraft.

Quoting NAV20 (Reply 73):
Beyond that, you have to look at the role of organisations like the NTSB. It is not to apportion blame

Correct, and, incidentally neither am I. The most important thing about accident investigation is that all factors are considered and all appropriate actions carried forward to prevent (or limit the chaces of) reoccurence.

Must go to work now, talk later.

Regards,

Jim
Erm, is this thing on?
 
GBan
Posts: 488
Joined: Thu Jun 16, 2005 5:10 pm

RE: American Airlines 587 A Closer Look

Thu Aug 25, 2005 4:26 pm

Quoting RedFlyer (Reply 70):
Your logic implies that to obtain entry into the NTSB, Coa747 has to agree with everything they say. "Herd" mentality is not conducive to obtaining the objective - one need only look at what a "herd" mentality resulted in with the two shuttle disasters endured by NASA.

I don't think the point is whether he "agrees to everything they say". The point is that he unfortunately provided numerous wrong "facts" and mixed facts with opinion. To be honest, after reading the posts I wouldn't hire him in my company. Furtunately this does not hurt him, he won't apply for an engineering job in Germany  Wink
 
coa747
Topic Author
Posts: 380
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 12:23 am

Thank you for all the profession career advice. It is nice to know that so many of you have an opinion as to my abilities having never met me. I didn’t know you had to be an aviation expert to post in this forum. If anyone had actual bothered to read my first post you would see that I am a STUDENT! I never claimed to be an expert. Some of my information was incorrect and I have been called on it. I acccept that as I am a STUDENT and I posted this topic to stimulate discussion and gain some insite from experts like Mrocktor and learn something. Healthy discussion is good and obviously others liked the topic and have contributed valuable posts. I say again contrary to what some believe not everything in life is a A vs. B war! The NTSB has gotten in wrong before and I’m not saying they have this time I just would have liked to see them look into some of the pilot reports. I mentioned two examples from a 68+ page incident log.

United 811 should have taught us all something. How could the board come to a finding of the probable cause without even examining the cargo door which was at the bottom of the Pacific ocean and should have been the center of the investigation. It wasn’t until a group led by Lee Campbell’s parents demanded the door be recovered that the search was started. Even after recovering the door and the evidence proved that the boards theory was incorrect they would not change the finding. It took two Pan Am 747 incidents to change the boards mind. First Pan Am flight departed Heathrow and could not pressurize at altitude and returned to land and the crew discovered the cargo door was open by 4 inches. Second incident occurred on the ground at JFK when the aircraft was ready to depart when it was discovered the door had opened itself uncommanded. Faced with this evidence the NTSB modified its finding. It is always healthy to question other peoples findings when things don’t add up.
 
kevi747
Posts: 991
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 1:51 am

Quoting Coa747 (Thread starter):
uncommanded yawing severe enough to force buckling and popping sounds from passenger exit doors,

That happens on every A300 flight. Those doors are very loud. The popping used to scare me, but I'm used to it now. But I love working on the A300 because of the Caribbean destinations it goes to and the size/layout of the cabin. But no one can deny that its a complete piece of crap. It breaks down all the time, and we NEVER arrive on time because of the mechanical problems. And they aren't that old either. The interiors are just torn to hell from all the use they get. Plus the air conditioner never works, and the cabin always hotter than hell while on the ground. But other than that, it's great.  Wink
"Reality has a well-known liberal bias." --Stephen Colbert
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 2:06 am

Kevi747 what causes the doors to pop? So the A300 at least American’s would qualify as hanger queens. What routes are they mostly used on. I know they are used from JFK to the Dominican a lot and I would imagine to San Juan but what others? Has American considered getting rid of them if they are so unreliable?
 
mrocktor
Posts: 1391
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 2:09 am

Quoting RedFlyer (Reply 55):
So that begs the question: what constitutes "repeatedly"? One full movement in one direction and another back in the opposite direction? Two full movements in either direction? Three? More?

Agressive control inputs are assumed to be countering a disturbance, such as a sudden gust, an engine failure and so on. Thus it is assumed that an agressive input is made to counteract the disturbance, and that after that gradual maneuvering is possible.

The requirement as cited by 777236ER is consistent with this scenario.

Quoting RedFlyer (Reply 60):
Is that why there was a chorus of pilots that protested the results of the NTSB?

Never take seriously what a lawyer says. True or false wouldn't matter, the pilots union would try to evade their share of responsibility for the accident anyway.

Quoting RedFlyer (Reply 60):
Operating procedures are known to vary from airline to airline. That doesn't mean one is right nor the other wrong.

True, and inconsistency in this matter was cited as a contributing cause to the accident.

Quoting GPHOTO (Reply 62):
Too many people assume that Pilot Error means that the pilot was an idiot, incompetent or should never have been in the cockpit. However, it means what it says, that the pilot made an error. Its a very blunt and often harsh term and having read a number of accident investigations, I can almost always feel a great deal of sympathy for the pilot involved.

EXCELLENT!

Quoting GPHOTO (Reply 62):
Pilot Error causes more airliner accidents (the figures are worse for non-airliner air accidents) than anything else. There are many sources of information for this,
see here for one.

As NAV20 argued in his post, this is not only due to the fallibility inherent to human beings. The fact is that we (and I mean aircraft design engineers) design aircraft to give the pilot more and more chances of saving a potentially catastrophic situation. This means that for most situations there is something the pilot could have done to save the day. This contributes to the "pilot error" statistic, but in truth is a reflection of the improving safety level of aviation in general.

Basically, it means that for a crash to happen the plane must fail and the pilot must fail. Sometimes it happens, but there is no avoiding that entirely.

Today the considerations about "human factors" are a big deal in designing aircraft systems. We no longer are content to imagine a system failure and draft up a procedure for it. We construct a scenario, what does the pilot know? How does the aircraft behave? How will the pilot interpret the scenario and how can we design the system to induce him to make the right decision?

mrocktor
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 2:44 am

Mrocktor are you a human factors specialist? This is my specific area of interest in my graduate studies. The human factor is perhaps the most complex element of a crash and the most difficult to discern. Most people see human factors as simply what the pilot did and what happened but it is much more complex than that. You have to consider his interactions with aircraft systems both mechanical and human. Why did he choose to make the decisions he did and what factors influenced those decisions. Stress is one of the most difficult elements to reproduce and our understanding of how it affects a person is very limited. This is one element that current training in the simulator can not replicate. Take American 965 as an example. We know the main cause of the crash was human error but what factors contributed to it. Why did the captain decide to deviate from procedure and accept a straight in approach knowing he was too high and too close in. What factors led him to forget to stow the spoilers. This is what I believe is missing from the 587 investigation. There is no explanation as to why the captain made the inputs he did.
 
FinnWings
Posts: 633
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 3:44 am

Quoting NAV20 (Reply 49):
No problem, FinnWings, glad you realised that I wasn't just contradicting you for its own sake. Nice to talk to someone else who can imagine what it might be like to be at the control of a big airliner that is being thrown into 20+-degree banks in both directions at only 2,000 feet.....

Can't answer all the questions you raise in a short post, but I'd urge you to read the full NTSB Report; I put a link on above, if you can't find it I'll happily repost it.

Thanks a lot of those nice words, NAV20!  veryhappy 
I'll definitely try to read the full NTSB report soon like you recommended when I have more time!

Quoting Kevi747 (Reply 77):
But no one can deny that its a complete piece of crap. It breaks down all the time, and we NEVER arrive on time because of the mechanical problems.

Well, perhaps the A300 isn't state-of-the-art these days anymore and surely AA has logged huge amount hours on those birds during the past years. What comes to mx issues, I would be very careful to claim that the aircraft is "piece of crap". A300 is very reliable workhorse and considering the age of those aircrafts I highly doubt that there is more mx issues than with equally old MD-80s or B737s on AA fleet or otherwise that reflects more like the quality of AA maintenance than A300.

Quoting RedFlyer (Reply 52):
Sorry, in all my flight training and in all the manuals I have, no where does it state that an abrupt movement means ONE movement.

No problem RedFlyer, I wouldn't believe either if someone would suggest something like that in the internet, especially if most of the other pilots and CFIs would disagree. My "eye opener" was an aerospace engineer who told to me about this issue and showed some stress calculations+actual certifying methods aircrafts.

Quoting Coa747 (Reply 76):
Thank you for all the profession career advice. It is nice to know that so many of you have an opinion as to my abilities having never met me. I didn’t know you had to be an aviation expert to post in this forum. If anyone had actual bothered to read my first post you would see that I am a STUDENT! I never claimed to be an expert.

Coa747, please be patient... This forum could be a little bit harsh place sometimes, but you don't definitely need to be an expert to write here. This is great place to ask questions and usually you'll get a wide variety of answers and a lot of different opinions. Most of here are able to discuss about things in a constructive way, but just like in the real life others aren't able to do that. Don't worry about that minority...but you should be able to handle negative feedback as well. You started up an interesting discussion which got many replies. On behalf of me, welcome to A.net!

Best Regards,
FinnWings
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 5:10 am

Thanks for the welcome FinnWings. I don't mind the criticism that is how you learn. I have learned a lot of great information from the posts in this topic. I guess I just haven't figured out how to filter out the small minority who insist on being rude and hostile. I posted my second topic a while ago so we will see how it goes.
 
GPHOTO
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 5:21 am

Damn, I wrote a real long piece and wiped it somehow. I'm not going to do it again. In short, I'm just going to repeat the message I joined in this debate for (and it isn't aimed at any one individual, just trying to clear up misconceptions about a term often seen but rarely understood) - the term pilot error is used in relation to a large range of pilot attributable accidents ranging from genuine incompetence to just damn unlucky. You cannot and should not view the term 'Pilot Error' on its own, either to criticise a pilot or to accuse others of using him as a scapegoat who will carry the can for what went wrong. It must be viewed in the context of the report as a whole.

The AA 587 accident will have as its primary cause 'pilot error' because the pilot was responsible for the control inputs that over-stressed the airframe, inputs that should not have been applied. The pilot wasn't stupid - he wouldn't have applied those inputs if he thought it would get him (or anyone else) killed. The investigators will have investigated various scenarios as to WHY the pilot did so, in great detail, including asking questions of AAs training program and the manufacturers advice to its customers. None of the posters here have done any of these things, nor have we asked the pilot why he felt his was the correct response. For that reason I see no purpose in trying to find fault or difference with the report until I see a significant number of aviation professionals call attention to any discrepancies.

Coa747:

Good luck on your choice of career, its one I sometimes wish I had chosen. I hope you find you have little work to do in your chosen profession, if you see what I am getting at. Don't be afraid to investigate every avenue and consider every oddity.

Can I recommend the work of Macarthur Job to you, or anyone who wants a readable and interesting analysis of many major accidents. He and his illustrator have managed to deliver books which manage to easily convey what happened, the work of the accident investigators and what they found (and more importantly, why they reach their conclusions) without the overly-sensational narratives that appear in many texts aimed at the casual reader. These situations contain enough drama on their own. The text is well supplemented by illustrations and voice transcripts which allow you to visualise with ease how things occured, why and how the chain of events fits together. I am sure you will find his work of great value.

Best regards,

Jim
Erm, is this thing on?
 
VuelingAirbus
Posts: 112
Joined: Fri Aug 26, 2005 4:44 am

RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 5:30 am

Hello everyone... After several years of using this site i finally decided to sign up (yeah!!!). I want to introduce myself very quickly in my very first post. I am currently a First Officer on Airbus A320 with 4500 total time (including 1500 hrs. on MD-83 and 2700 hrs. on the A320 family). That should be enough about me and now to this very interesting post.

I can remember this accident very well because it happened during a pilot/managment meeting in my previous company where we were discussing pay-cuts (shortly after 9/11) and the emotions it stirred up. I don't want to blame the pilots of AA 587 because they reacted as trained (or close to it). However - I was trained that i MUST NOT use the rudder inflight except to decrap or in case of engine failure. And as far as i can remember the training at AA was mainly upset recovery due to a stall (not to counteract turbulence).

On a side note (and i dont want to point fingers here - especially at someone who recently had his BFR) - but an easy search with google came up with two very interesting links i want to share with you.

http://www.ntsb.gov/events/2001/AA587/exhibits/240009.pdf

http://www.flyingmag.com/article.asp?section_id=12&article_id=527

here the most important quotes from the BOEING COMMERCIAL AIRPLANE GROUPFLIGHT OPERATIONS TECHNICAL BULLETIN (note it comes from Boeing and not Airbus):

aggressive maneuvering using “sequential full opposite rudder inputs” can potentially lead to “structural loads that exceed those addressed by the requirements

When the rudder is reversed at this sequential over yaw/sideslip angle, the rudder induced fin force is added to the sideslip induced fin force (See Figure 4 & 5). The resulting structural loads can exceed the limit loads and possibly the ultimate loads, which can result in structural damage.

A structural design maneuvering speed, Va, is defined for evaluating airplane structural design. At or below this speed, Boeing airplanes are capable of sustaining a single input to any set of control surfaces (elevators, ailerons, rudder(s)) to their maximum available authority (as limited by control surface limiters, blowdown, or control stops). These control surface inputs are to be in one axis (not in combination) and do not include control input reversal or oscillatory inputs.

In simple pilot terms, if you are in a stall, don’t use the rudder; if you are not in a stall, you don’t need the rudder. The rudder in a large transport airplane is typically used for trim, engine failure, and crosswind takeoff and landing. Only under an extreme condition, such as loss of a flap, mid air collision, or where an airplane has pitched to a very high pitch attitude and a pushover or thrust change has already been unsuccessful, should careful rudder input in the direction of the desired roll be considered to induce a rolling maneuver to start the nose down or provide the desired bank angle. A rudder input is never the preferred initial response for events such as a wake vortex encounter, windshear encounter, or to reduce bank angle preceding an imminent stall recovery.


please dont't flame me for the lenght of the post but i think it should clearly answer some questiond and clarify misunderstandings...

I am glad to be a A.Net member now - its a great site...
 
kevi747
Posts: 991
Joined: Sat Apr 14, 2001 5:59 pm

RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 5:50 am

Quoting FinnWings (Reply 81):
, I would be very careful to claim that the aircraft is "piece of crap". A300 is very reliable workhorse

You are absolutely wrong. A300 flights are consistently delayed and or cancelled because of mechanical problems.

Quoting FinnWings (Reply 81):
I highly doubt that there is more mx issues than with equally old MD-80s or B737s on AA fleet or otherwise that reflects more like the quality of AA maintenance than A300.

Once again you are completely wrong. If it was all of our airplane types constantly breaking down then I would agree with you. And yes, of course, other aircraft are delayed and go out of service from time to time, but not near as often as the Airbus. I fly the A300 more than any other airplane, both because of the destinations it flies to, the PAX it carries, and the size of the cabin. (Plus I'm pretty junior and its all I can hold.  Wink ) But it is not known amongst pilots, F/A's, mechanics, agents, or anyone else working at the airline to be anything close to "reliable:.

Plus, they are so damned hot all the time.

Quoting Coa747 (Reply 78):
Kevi747 what causes the doors to pop?

A mechanic told me that when the door is closed it has a bunch of contact points within the door frame that come into contact with points on the door itself. It kind of just rests there until after takeoff when the airplane starts to pressurize causing the door to be sealed tightly. The popping is caused:

a) on the ground by the door shifting in its frame as the airplane bumps around on the taxiways; and

b) in the air (usually just after T/O) as the pressure starts to push the door against its pressure points in the door frame. Once it has pressurized it's pushed against the doorframe so hard it can't move anymore and the popping stops.

Do you get what I'm saying? The mechanic made me understand it (and it was easier because we were standing next to the door actually looking at it) but I don't know if I described it well. Anyway, sometimes the sound is VERY loud and scares the PAX.
"Reality has a well-known liberal bias." --Stephen Colbert
 
mrocktor
Posts: 1391
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 5:55 am

Quoting Coa747 (Reply 80):
Mrocktor are you a human factors specialist?

No, though much of my work includes human factors discussions with the specialists.

Quoting Coa747 (Reply 80):
There is no explanation as to why the captain made the inputs he did.

I would sugest looking at the attitude and attitude rate of change (accelerations) of the aircraft during the incident. Don't forget to allow for the fact that pilot responses are delayed with regards to the stimuli that prompted them.

This video is a good watch. The pilot is clearly fighting the aircraft when he performs the detent to detent rudder movemets. Also, he was far from a dangerous attitude before the PIO (pilot induced oscillation) began.

mrocktor
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 6:08 am

Thanks for the explanation Kevi747. I would have to say as a passenger that would certainly scare me. I wonder why other types don't make that sound as they pressurize?

GPHOTO thanks for the words of encouragement. Yes I definetly agree Air Disaster volumes 1-4 are very informative and the illustrations are precise and accurate. They really helps one understand some very technical subjects. Everyone interested in Aviation should read them.

I am curious as to if anyone knows the blowdown limits of the A300 rudder at the speed 587 was traveling when it broke up.

The only reference I have is for the 737 and that is around 22 degrees from the neutral position at 300 knots. With full deflection under no aerodynamic loads being 26 degrees.
 
GBan
Posts: 488
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 6:24 am

Quoting Coa747 (Reply 76):
If anyone had actual bothered to read my first post you would see that I am a STUDENT!



Quoting Coa747 (Reply 82):
I guess I just haven't figured out how to filter out the small minority who insist on being rude and hostile.

Coa747, I did read your first post stating that you are a student and that you hope to work for the NTSB some time. Otherwise I wouldn't have made a statement on employment chances. I am sorry if it came over "rude and hostile" when I said that I would not employ you after reading all your posts.

Quoting Coa747 (Reply 76):
The NTSB has gotten in wrong before and I’m not saying they have this time I just would have liked to see them look into some of the pilot reports. I mentioned two examples from a 68+ page incident log.

If this is your message we agree. Your initial posts did sound different.

Have a good time on A.Net!

Quoting VuelingAirbus (Reply 84):
please dont't flame me for the lenght of the post but i think it should clearly answer some questiond and clarify misunderstandings...

I personally don't mind lengthy posts if they are like yours! Welcome and thanks for sharing this information!
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 6:33 am

Sorry for the ranting GBan I can see how my earlier posts came across that way. My fault, I didn't compose my thoughts very well. No harm done. Thanks for sharing your thoughts I have learned a lot and will try not to take things so personal next time.
 
coa747
Topic Author
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 7:11 am

In an earlier post I had made cryptic mention of Boeing aircraft having a system to limit the amount of rudder deflection in flight. This is what I was trying to get at. The 737NG has a load limiter to limit rudder authority in flight. I would assume this would be to prevent rudder deflection to the extent that structural failure occurs. My question is does the A300 have a system such as this in place. It would seem this should be included on all commercial aircraft either through retrofit or standard on all new production as it would help prevent the rudder from over traveling during flight and causing a structural failure or a hard over.
Load Limiter - NG

The NG's do not have an RPR but a Load Limiter instead. At speeds above 137kts, hydraulic system A pressure to the rudder PCU is reduced (to 1450psi). This reduces rudder output force by 25% which reduces rudder authority at blowdown after take-off and before landing. On the new rudder system (2003 onwards), both hydraulic system A and B pressure is reduced (to 2200psi) within the main PCU above 137kts.

Source is: http://www.b737.org.uk/theruddersystem.htm
 
VuelingAirbus
Posts: 112
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 7:50 am

The problem is/was not the limited/unresticted travel of the rudder. Modern transport aircraft (and believe it or not even the A300 falls into that category) are designed to limit rudder travel as the aircraft speed increases. This is done by different design philosophies (for example some aircraft limit the actual rudder travel but others limit the pedals). The Airbus A300 rudder travel limiter starts at 165 knoths and gradualy limits the rudder travel. At 250 knots (the actual speed of AA587 when the accident happened) the rudder travel is limited to 10 degrees versus a maximum of 30 degrees deflection below 165. This is due to the fact that the faster you fly the more effective the rudder becomes. So the actual deflection does not really matter, as it is also restricted in the Airbus A300. The problem is that you can - and as proven will - exceed certified limits if you give reversal rudder inputs (in plain language - NO civil transport aircraft is designed for that kind of maneuver). The pilot induced (and i dont blame him because he reacted as trained) a catastrophic oscilation which led to the seperation of the rudder due an exceedance of the ultimate design limit of the rudder.

let me give you another example of the problem with composite tailplanes. our flight attendants were always complaining that in an A321 you have almost severe turbulence in the aft galley and in the front of the aircraft you didn't feel anything. Airbus was pioneering the use of compisites when they launched the A310/A300 but from a material standpoint composites are less flexible than aluminium. So if you have gusts hitting the vertical stabalizer it does not get absorbed and therfore the whole back of the aircraft is exposed to it. Aluminium bends much more so it takes away (lets say absorbes much more of the energy) and therefore the tail moves much less. And every flight attendant will agree the it is a pain having to fly in the back of an Airbus during turbulence.

Nevertheless it was tested and fulfilled all requirements set by JAA and FAA - in this accident the tail seperates above ultimate load - it is a very unfortunate accident, but let us learn from it and not blame the pilots or manufacturer. Like any other accident - let us learn from it and not waste more lifes than the ones already been lost - lets make pilots aware that it is possible to overstress their aircraft and train them accordingly...
 
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777wt
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 8:01 am

Quoting Philb (Reply 64):

Where would have that story of the a/c tail hitting the ground arised from then. It was brought up so it could have some info, pherps interview the techs who built that plane from that time?

Hell you could make a car at a factory and if it fell off the guide into the pit, you could pull it back up, repair the frame and replace the damaged parts and send it on it's way down the line which it will end up on a dealer's lot to be brought by the customer which in return will turn out to be a leamon.
 
boysteve
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 8:31 am

I watched a Discovery channel documentary on this incident. After the full investigation both Airbus and Boeing issued a statement warning of excessive rudder movement. It was concluded that Airbus knew that it might be an issue but hadn't disclosed it before. Boeing had either acted in the same way, or didn't know that this phenomena could also affect their aircraft. Neither manufacturer sued the program makers after broadcast!
 
coa747
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 8:31 am

Doesn't the airflow over the tail also have a natural dapening effect that prevents its from being fully deflected to its full extent as would be the case if it was stationary on the ramp. Doesn't this effect increase with speed progressively limiting its deflection even further. I understand now. So there is really no way to prevent a pilot from overstressing the airframe through excessive rudder inputs. So what purpose does the limiter have? Is it an extra safety margin. In the US Air 427 crash the rudder did go hard over didn't it or did it just experience flutter before it jammed? What could cause an uncommanded rudder movement?
 
VuelingAirbus
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 9:03 am

in short words (short because i dont want to be known as the one who has neverending posts)... i would recommend to google some of the questions you have or just simply take the time to click and read some of the very usefull links provided by fellow A.netters... Put yourself into the shoes of an engineer who most likely does not have to operate/pilot the aircraft (and Airbus seems to have more of them than Boeing - as a proof you just have to compare flight crew manuals). The engineer designs the aircraft to fullfill regulatory requirenments, in that case load limits. The rudder travel limiter could therefore also be called a load limiter. To be more specific - the rudder travel limiter limits the travel to a value which keeps the load on the fin constant as speed increases (30 degrees at 165 knots to 4 degrees at above 350 knots). In other words for the same rudder input to create less load on the fin you need to fly less than 165 knots (as the rudder reaches its mechanical stop at 30 degrees) - above 165 knots you have the same load on the fin with the same input as the rudder travel (deflection) is limited...

I hope that answers your question about the rudder travel limiter...

RGDS

[Edited 2005-08-26 02:16:04]
 
coa747
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 9:51 am

Okay thanks for the explanation. That makes more sense now. I will see what information I can find on the other questions. Thanks for your expertise.

So out of the initial questions I raised I believe all but two have been answered or explained.

1. report from American pilots detailing specific incidents of uncommanded rudder deflection on the A300. (Unresolved) but posibly not relevant to crash also popping sound has been explained as routine.

2. FedEx experienced related issues with its Airbus fleet also not included in the final report. (Unresolved but not relavent to crash as fin was found to be structurally sound)

3. Manufacturer modified the A300 control system software for passenger comfort following the crash of flight 587. (Partially resolved, has direct link to point 1)

4. The accident aircraft's previous day log entry recorded significant problems with the computerized flight management system. (Yaw damper issue seems to be relevant)

5. Airbus parameters for stress-testing (Not relevant to crash but intersting to note as they do not seem to be a good model for in service conditions)

6. Airbus internal memo (not new information as all aircraft are vulnerable to this type of failure)
 
VuelingAirbus
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 10:03 am

i found another link which is dated from 1998 (two years before the accident) and let me quote:

We also spent a lot of time discussing the use of rudder....

We finally got the training managers to agree to play down the use of rudder in their existing courses. But we do not say never use the rudder at low speed. We say that, if necessary, the aileron inputs can be assisted by coordinated rudder in the direction of the desired roll. We also caution that "excessive rudder can cause excessive sideslip, which could lead to departure from controlled flight".



http://www.pilotosdeiberia.com/areat...airbus_sfo/17airpl_upset_recov.htm

there was another incident involving an American A300 in 1997 and that lead to the conclusions Airbus published regarding the use of rudder (see second link)

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001208X07893&key=1

so it can be summarized that Airbus was aware of the misuse of rudder and it expressed its concerns to the airlines but some (namely American) didn't want to implement those recomendations - so noone can say it came as a suprise and i am sorry to say that and especialy with respect to the victims of AA587 but the training conducted by American was sooner or later leading to the events which unfortunatly caused the accident...
 
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Starlionblue
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 12:35 pm

Quoting Coa747 (Reply 94):
Doesn't the airflow over the tail also have a natural dapening effect that prevents its from being fully deflected to its full extent as would be the case if it was stationary on the ramp. Doesn't this effect increase with speed progressively limiting its deflection even further.

In theory yes. Obviously at higher speed airflow will tend to make a control surface resist deflection more than at low speed. However given hydraulic aids this may not translate to a greater stiffness in the controls. And therein lies the problem.
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RE: American Airlines 587 A Closer Look

Fri Aug 26, 2005 12:40 pm

Quoting VuelingAirbus (Reply 84):
Hello everyone... After several years of using this site i finally decided to sign up (yeah!!!). I want to introduce myself very quickly in my very first post.

VuelingAirbus: your posts - especially for one who just joined - are most refreshing, insightful, professional, and polite. For starters, welcome to my RU list!

My gripe all along with this thread, and perhaps I was not sufficiently on point, is that all pilots have been taught for many years that abrupt control inputs below Va will not have a deleterious affect on an airframe. I know because that is what was ingrained in me and also because shortly after the AA587 report I spoke with several airline pilot acquaintenances of mine and they were very surprised as well. While they all said they didn't understand the use of rudder to counter the affects of turbulence, they were nevertheless surprised that the vertical stab would detach from the airframe, especially at such a low speed (don't forget, the aircraft was still on its initial climb, having been airborne for only something like 90 seconds).

Whether anyone on this forum wants to believe it or not, there is a common belief in the industry that there was more to this accident than mere use of aggressive rudder inputs or even that the 300's rudder was overly sensitive. Most people I've spoken with believe the rudder/vertical stab was already prone to failure. (NOTE: I AM NOT SAYING IT IS A DEFECT WITH THE AIRBUS 300 BUT, RATHER, THAT THE VERTICAL STAB WAS ALREADY WEAKENED OR DAMAGED). The reason being this was the only time an incident like this occured without any external factors. If you think about how many millions of hours have been flown in various large jets over the decades, how many have suffered a catastrophic failure such as this from mere aggressive use of controls? More to the point, does anyone really think the copilot of AA587 was the only pilot throughout the past few decades and millions of hours of flight who did something with control inputs that he/she wasn't supposed to do?

As far as I'm concerned, there are two issues here: the first being the use of rudder to counter the affects of turbulence and the second being the detachment of the vertical stab at such a low speed. If all you do is take a look at the first issue then, yes, the pilot is to blame because he used the rudder for something that it was never intended for. However, that still does not address entirely the issue of why the vertical stab separated at such a LOW speed.

In any event, VuelingAirbus, your inputs and references are most welcome. I hope to see more of your posts on this forum.

Best regards,
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