Interesting note about AA Airbus crash in NYC

[Rainboe]

airsupport,

If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.

Well the exact cause of several 737 rudder hardover crashes was never precisely pinned down, so why are 737s flying today? Because we know the problem, we've been trained how to handle it and it is a known risk. So are you saying that we don't know the fin problem? Since my basic training, I was told in no uncertain terms to leave the rudder alone- it's for engine failure, spin recovery, aerobatics. If I ever tried to cheat on approach and slip a little rudder in to line up, I got very short treatment. If I touched the rudder on approach on large jets, I had rude comments made. I think the whole of British aviation is aware you don't mess about with rudder. So how does the public feel watching an AA Captain at the accident hearing answering earnestly "no Sir, we didn't know you couldn't apply rudder like that!" There comes a time when trying to protect one man's reputation becomes counter-productive to safety. I suggest the lesson is drilled home without doubt- no professional pilot should be flying unaware that the fin is not designed for this, and certainly not stressed for it, on any other jet either.

[bubbers44]

Can I watch your first landing in a taildragger like a Twin Beach landing in a crab?

[barit1]

Some folks have Multi-engine licenses "Restricted to centerline thrust only".

For a few decades I've advocated licenses "restricted to tricycle undercarriage" until tailwheel competency is demonstrated.

[airsupport]

Rainboe,
There you go, twisting my words AGAIN.
I said

If the fin of a serviceable Airliner can be ripped off purely by Pilot cockpit inputs, then I for one don't think that Airliner should be flying.

The B737 incidents you are on about IF TRUE, were with an UNSERVICABLE Airliner/s.
Just as was the case I still feel with the AA A300 out of JFK.
I still honestly think that if any serviceable Airliner (that is no faulty components or weakened structure) can be brought down PURELY by mechanically allowable (whether normal or not) Pilot inputs then it should NOT be flying.

[Rainboe]

I'm not twisting your words, but I do not believe any Boeing fin could take the strain this fin was put under either If I recall correctly, the photographs of the breakages that occurred showed the metal lugs parted company at the attachments- I'm not sure how much the carbon fibre fin was actually involved in the separation.
I have flown DHC Chipmunk and Auster tailwheels. That class of aeroplane has a much tougher structure with the fin integral with the fuselage structure. Perch a fin on top of the fuselage and attached at the base by lugs, and you have a modern airliner construction that won't take abuse, especially at faster speeds.

[DozyWannabe]

Originally Posted by airsupport

I still honestly think that if any serviceable Airliner (that is no faulty components or weakened structure) can be brought down PURELY by mechanically allowable (whether normal or not) Pilot inputs then it should NOT be flying.

I repeat Mad (Flt) Scientists reply from earlier, which you've apparently missed - or maybe you're wilfully ignoring:

Originally Posted by Mad (Flt) Scientist)

You just grounded every single aircraft flying

Once again, severe enough pilot inputs will cause catastrophic damage to every aircraft out there. There's no doubt about that; the only variable is the degree of severity required, but push them hard enough and they all will break.

*caveat: except POSSIBLY FBW-envelope protected types *cough*Airbus*cough* - but even those may not be fully immune. We don't design aircraft to be flown in a carefree manner, generally, and never in a careless manner.

I'd be tempted to be more specific and say that you'd be grounding every airliner out there, but his point still stands. Have a look at the first few pages of this article:

http://www.flyingmag.com/article.asp...article_id=527

Va (AKA Manouevering Speed) has been a fact of life for pilots for decades - although it was primarily concerned with structural integrity involving wings and horizontal stabilisers, the vertical stab was apparently not originally considered in these calculations.

The simple fact is that your criteria, i.e. being able to rip the vertical stabiliser off through pilot action alone - are applicable to pretty much every large transport-category aircraft currently flying, be they Boeing, Airbus, Tupolev... whatever.

[Mad (Flt) Scientist]

Originally Posted by DozyWannabe

I'd be tempted to be more specific and say that you'd be grounding every airliner out there,

Yes, my apologies, I carelessly used "aircraft"; obviously there are some aircraft that may be exceptions.

[airsupport]

Originally Posted by DozyWannabe

I repeat Mad (Flt) Scientists reply from earlier, which you've apparently missed - or maybe you're wilfully ignoring:
I'd be tempted to be more specific and say that you'd be grounding every airliner out there, but his point still stands. Have a look at the first few pages of this article:
http://www.flyingmag.com/article.asp...article_id=527
Va (AKA Manouevering Speed) has been a fact of life for pilots for decades - although it was primarily concerned with structural integrity involving wings and horizontal stabilisers, the vertical stab was apparently not originally considered in these calculations.
The simple fact is that your criteria, i.e. being able to rip the vertical stabiliser off through pilot action alone - are applicable to pretty much every large transport-category aircraft currently flying, be they Boeing, Airbus, Tupolev... whatever.

Yes I ignored it, I was hoping to keep the discussions logical.

IF (which I hope is NOT true) there are ANY Commercial Airliners out there now, where failure of primary structure and loss of the hull with all the souls on board, can be caused by ONLY (mechanically or electronically) allowable movements of Pilot controls, without any defects on the Aircraft, then they should be grounded IMMEDIATELY.

The scenario is just too ridiculous to to be true, hopefully.

Can you imagine the outcry if this was true say with a car, that on a particular make and model of car, in perfect working order, simply moving one of the pedals "too far or hard" would cause loss of the car and all the lives on board?

That car would quite rightly be removed from the roads immediately, just as these Airliners (IF what you say is true) should be removed from the skies IMMEDIATELY.

[Mad (Flt) Scientist]

It was ALREADY widely known, even before this accident, that full application of controls at speeds above Va - so called "manoeuvring speed" - could cause structural failure.

All that happened here was the exposure to the fact that aggressive control input, even below Va, can cause catastrophic effects.

To take your motoring analogy - any car will spin if handled badly in a corner. Many high vehicles will topple similarly. Full throttle will, if applied long enough, overspeed the tyres above their rated speeds. gear changes from top to first, or reverse, will destroy the engine. Sudden braking may cause skids and loss of control.

And we haven't started yet on the ability to drive into walls, other vehicles, etc.

All machinery must be operated with, and treated with, respect. Airline pilots require training and licensing to qualify them to operate the complex, and dangerous, machines they fly. If the machines were foolproof, the airlines could save a lot of training bills by simply hiring fools.

[airsupport]

I give up.

It is a waste of time expecting sensible debate here, I will save it for the picnic.

[Rainboe]

One gets a similar feeling to know there appears to be a large group of pilots, apparently uniquely American, and from one particular large airline with an eagle on a silver tail, who are professing complete ignorance to any limitation on being able to mistreat aeroplane controls without having structural failure 'as long as you are below Va'. Large airliners are not F16s, and treating an airliner rudder as if you are flying a Pitts Special with multiple rapid reversals is just not on. What is more frightening is there appears to be an airline full of pilots who can only point to 'design defect' and not recognise the real cause. Your picnic, whatever it is, needs to be a comprehensive breakdown of how to handle unusual attitudes and recommended techniques on the controls.

[Shore Guy]

Gentlemen and Ladies (not so much in order of preference or political correctness, but order of “who does it”),


I am not familiar with the basic and advanced training concepts in areas other than North America, but……

I would wager a months pay that pilots on the west side of the Atlantic, at a ration of 9 to 1 or greater, would have, prior to AA 587, said that if all systems were operating normally (specifically rudder limiter), that “stop to stop” would be within Part 25 certification limits and would NOT have resulted in catastrophic airframe damage. I was wrong…..We were wrong.

After the accident, and after research, it became apparent that even NACA documents from the twenties showed this was not true. But we were not educated or trained of such, in fact, for many of us, the opposite. There is reference on the web still today that –

” VA
design maneuvering speed (stalling speed at the maximum legal G-force, and hence the maximum speed at which abrupt, full deflection, control inputs will not cause the aircraft to exceed its G-force limit). Maneuvering speed is limited by aircraft structural characteristics.

1-18-07



Not true, as a result of the investigation into AA 587.


Perhaps the pilot/pilots involved were “rough” with the airframe. But with existing knowledge, no one would have thought they would compromise the airframe, resulting in a catastrophic failure.

Yes, the Advanced Manueveing Course may have been a contributor. So may have the “Rube Golberg” Rudder Limeter system incorporated in the A-300 series (what were they thinking?).

Unfortunatly in this business, wreckage and bodies are the major empasis for education. Sad but true.

“There but for the grace of God……..”

[Rainboe]

Just as a reminder, control useage can be viewed here:
http://www.alexisparkinn.com/photoga...-animation.wmv

Whilst I can appreciate there may be some adverse opinion of the design, there is also equal adverse opinion of piloting technique in this incident.

[Clandestino]

Originally Posted by Mad (Flt) Scientist

*caveat: except POSSIBLY FBW-envelope protected types *cough*Airbus*cough* - but even those may not be fully immune.

A320s envelope protection through FBW does not extend to yaw/sideslip. And that´s because, once again, rudder is not primary control on any transport category aircraft and shouldn´t be used as such. (not pointed at you Mad(flt)Sceintist, i got your point, just for the ones who might say that Airbus should protect their airplanes in yaw too). Of course you can and will use it to roll the plane but only after all of your ailerons and roll spoilers are rendered inoperative and that´s fairly unlikely event. Rolling with rudder while your roll control channel is operative will most likely lead to PIO (or APC if you´re newspeak´s fan) and PIO leads to... AA587. Just take a look at NTSB animation of cockpit control movements.

Despite JT´s warning to play the ball and not the man, I really, but really have the urge to comment on some posters here. I think it was mid 2002 when we got the letter from mr Caldarelli of ATR, not to use rudder for roll control and warning we might shed a tail if we don´t obey. Soon after that, the yellow FCOM pages arrived and by winter they were replaced by white pages, conveying the same message. Recently I´ve exchanged ATR FCOM for A320´s and there was the message again: don´t roll airplane with rudder and don´t cycle rudder, because when oscillations start, flying below Va does not offer protection. I think that every FCOM (AFM, POH. OM-B...) of the transport category airplane in the world has the same warning nowadays, as a result of AA587 accident. So people who are unable to grasp the significance of the warning, either don´t have the FCOM, or worse, have the FCOM but don´t bother to read it. I hope that no one here falls within bounds of second cathegory.

[Mad (Flt) Scientist]

Originally Posted by airsupport

I give up.
It is a waste of time expecting sensible debate here, I will save it for the picnic.

What kind of nonsensible contribution do you find in my statements?
It is a matter of simple engineering fact that aircraft are not designed - and not REQUIRED to be designed - to be immune to the consequences of any conceivable pilot input. I'll add to the last post by clandestino that every single one of our types has a similarly worded AFM/FCOM warning about the consequences of excessive control use.

You appear to be expecting 100% guarantees in your aircraft design; it doesn't exist in either structures or systems, and isn't required.

[airsupport]

Originally Posted by Mad (Flt) Scientist

What kind of nonsensible contribution do you find in my statements?
It is a matter of simple engineering fact that aircraft are not designed - and not REQUIRED to be designed - to be immune to the consequences of any conceivable pilot input. I'll add to the last post by clandestino that every single one of our types has a similarly worded AFM/FCOM warning about the consequences of excessive control use.
You appear to be expecting 100% guarantees in your aircraft design; it doesn't exist in either structures or systems, and isn't required.

Well that explains your position on this, by "every single one of our types", I take you work for Airbus?

You admit here that your aircraft are not designed to withstand all the stresses that may occur during flight, yet still it is not your fault, you blame the dead Pilot.

[Tree]

A point of interest:

The 737 rudder hard-overs did not cause the fin to separate.

[Mad (Flt) Scientist]

Originally Posted by airsupport

Well that explains your position on this, by "every single one of our types", I take you work for Airbus?
You admit here that your aircraft are not designed to withstand all the stresses that may occur during flight, yet still it is not your fault, you blame the dead Pilot.

Actually, no I do not work for Airbus, and never have. I have no reason to be biased towards them, or to blame anyone. I find it interesting that you assume that I must be coming from a position of inherent bias.

Once again, because you seem determined to ignore this point:
This could have happened similarly to any airliner in service today.

No-one - not Airbus, not Boeing, not Embraer, not Bombardier, no-one - designs their aircraft to sustain any conceivable control inputs. It's not an "admission", it's a simple statement of fact. Furthermore, the regulations to which all those aircraft are certified don't REQUIRE any conceivable control inputs to be considered; there are very specific cases defined, and if you do something more extreme than those cases, you are in unknown, and potentially VERY dangerous territory.

And if you read the NTSB report you'll see that they don't "blame the dead pilot" -at least not solely. As always, any accident has a number of causes, and the manner in which the aircraft was flown was but one part of the puzzle. There do seem to be some specifics of the flight control design which renders this design more vulnerable to such an event.

[Mad (Flt) Scientist]

Originally Posted by Tree

A point of interest:
The 737 rudder hard-overs did not cause the fin to separate.

The regulations for rudder load manoeuvres DO require that you be able to sustain a single full authority control application, so it's not surprising that the 737's didn't suffer fin failures in that event.

Oscillatory/reversing rudder inputs are outside the regulatory requirements, aircraft are not designed to withstand them, and that is unfortunately what happened in this accident.

[Mad (Flt) Scientist]

Finally, can I draw your attentions towards the recommendations section of the NTSB report:

Develop and disseminate guidance to transport-category pilots that
emphasizes that multiple full deflection, alternating flight control inputs
should not be necessary to control a transport-category airplane and that
such inputs might be indicative of an adverse aircraft-pilot coupling event
and thus should be avoided. (A-04-59)

Amend all relevant regulatory and advisory materials to clarify that
operating at or below maneuvering speed does not provide structural
protection against multiple full control inputs in one axis or full control
inputs in more than one axis at the same time. (A-04-60)

Taken together, these recommendations are the reason we have cauitionary notes in our AFMs, and why I believe EVERYBODY has such notes - we were basically ordered to put them in following the accident. Because they apply to everyone.