or better built planes puglist

and if you want a placard for stall recovery, I'm sure Air France will lead the way in placing the placard on their airbus fleet.

and I'll take a band aid any day...its better than an open wound.



by the way puglist


one plane I flew says don't move control wheel more than half way above FL400

now certainly I know that, but there is a placard...

oh maybe there should be one of those on the A300 too

I suppose for now that PPRuNe serves as a placard, I hope :)
As far as "better planes" go, the weight of reinforcing the VS to survive such abuse would be prohibitive

As illustrated in tdracer's post #100, and testified in the FAA's Final Rule on the matter, the 'placard' is now in the Airplane Flight Manuals of all transport category airplanes flying in the US.

Is that true? As a layman I would think that although the load factor at Va may exceed nlimit, the load would not exceed limit load. But then I don't know much about structures.

Is this what you are referring to?


Is 1997. recent or there was another incident recently that no one around seems to know about?

I remember that one too but this one about 20 years ago was on final approach to MIA requiring a go around because of uncommanded rudder movements that they could not stop. I would guess the NTSB would have blamed the pilots if they had crashed as they both thought was going to happen. I will try to find the report and post it.

A300 rudder actuator
 

HN39

The limit load (assuming the aircraft is designed by manoeuvre loads not by gust loads) would be 2.5g at MTOW and fwd CG limit. Strictly speaking that should be at MTOW less whatever fuel you burn to get there, but WTH! At Va you can just pull 2.5g at whatever weight has been used to define Va.

So if you are at a weight close to MTOW and at a speed above Va for that weight then you could in principle exceed both the 2.5g limit and the limit load. But at those conditions it is unlikely that one could pull enough 'g' to get anywhere near ultimate load (3.75g @ MTOW) if only because to get to a weight/airspeed condition where one could pull 3.75g one would have to burn off enough fuel to reduce the weight well below MTOW.

bubbers44

Thank you for posting that report, but since it says several times that re-engaging the yaw dampers made things slightly easier, and since the problem was diagnosed as a failed autopilot yaw actuator clutch I don't see how your position re yaw damper failure as a possible cause of AA587 rudder movements can be sustained. Comment?

Lucas Aerospace, which is now known as TRW Aeronautical Systems obviously builds parts for Boeing and others as well.

And as stated above nothing to do with yaw dampers.

Thanks Owain,

I probably misunderstood PA's remark.

As I said I was using the info the FO gave me after the incident. I didn't read this report until a couple of hours ago. I agree they found rudder actuator clutch problems. I am curious how that would cause uncommanded rudder deflections. Seems like the rudder would either work or not work.

I wonder, with the placard reading “don’t move the control wheel more than half-way above FL400” … I would presume that you would feel perfectly comfortable in moving the control wheel to ½ of it’s maximum throw (I would presume that would be somewhere in the neighborhood of 67 degrees either side of neutral, right?) even if you were operating at FL410. Since you’re comfortable in moving the control wheel this way, how about moving it to 67 degrees left, and then immediately moving it to 67 degrees right, and then back to 67 degrees left, and then back to 67 degrees right, and keep that up for some 6 to 8 repetitions. Please note, the control wheel would not be moved more than half-way, so there would be no problem … right?

And, since there is apparently no placcard saying anything about a similar use of the rudder - would you consder doing the same control deflections - this time to the "stop" (physical or rudder limiter) for that same 6 or 7 repetitions. No placcard ... so ... no problem? Maybe, taking a clue from the lateral control placard, you might consider limiting your rudder inputs and reversals to only the same ½ value?

Well, said – and, of course, quite accurate. And, in that same vein, with perhaps more than a little naiveté on my part, it would be my hope that ALL the readers here would take everything posted here as a potential fact until researched or thought through - or determined to be a perspective from a preconceived and/or prejudicial position and not necessarily willing to have the facts or truth lead to the ultimately correct conclusion. As for me personally, I choose to remain anonymous. The only reason for this decision, as I’ve said previously, is that I don’t think my employer would be appreciative of my “sounding off” (as you know I do) in such a public forum. I have a reputation with my employer for doing the same thing on the job and I pay for it regularly … but what I say is almost always retained within the organization in which I toil, and at least I still have my job - and I hope to keep it. However, if I were the janitor at the local Trailways Station – I can suspect what my “believability” might be … and, conversely, if I were the Senior Advisor to the FAA Administrator or the NTSB Deputy Chairman, whatever I say might (just might) enjoy some undeserved acceptance with little or no scrutiny. So, I prefer to offer what I offer in the hopes that I’ve made my points clearly and honestly enough to not depend on such “positional authority” to have anyone who reads what I say understand the accuracy of my comments.

Unless you are doing 8pt hesitation rolls rarely do you need much more than 20 percent control movement in any aircraft.

With all due respect, sincerely meant, I’m not at all sure that the Wake Turbulence training they received was insufficient or even wrong. Recall that the tail was twisted off the airplane due to the F/O’s indiscriminate use of rapid rudder and wheel control inputs to the stops and just as rapid reversals of both controllers on repeated occasions … BUT … that was the SECOND vortex encounter. The FIRST encounter was transitioned without incident – by the same F/O, doing exactly what he had been trained to do – essentially rely on the inherent stability of transport category airplanes, aided ever so slightly by very minor control wheel inputs to aid or hasten return to wings-level. In fact the rudder controls were barely moved and the rudder surface was barely displaced.

I guess we'll never know why this F/O did what he did the SECOND time he encountered a wing tip vortex on the SAME departure ... 5 or 6 seconds after the first encounter recovery ... but it certainly wasn't what he was trained to do.....

I guess he forgot everything he did a few seconds before and since that worked so well decided to stomp on the rudders until the tail fell off on the second encounter. Then again did anybody check the rudder actuator clutch? If it happened once it could happen again. I wonder if it was the same airplane?

The upset training we got we all knew was to use the rudder in low speed upsets on approach to maximize recovery not for 250 knot speeds. It had nothing to do with AA Airbus crash in my opinion.

On the surface that might look like an excellent question. But, I think the report indicates that when this particular error manifested itself on the approach into Miami (I think) the airplane was apparently found to have had maintenance cross-connecting the autopilot servos (wasn’t it) and they said that it was extremely difficult to move the rudder pedals. The rudder pedals on AA587 were apparently quite easily moved … as the F/O move them from stop to stop some 5 times in 7 seconds. That doesn’t sound like “very difficult to move.”

So you think FDR rudder inputs are measured at the pedals, not at the rudders?
I would like to see what the FDR showed on the MIA Incident when they couldn't move the rudder pedals but the rudder was out of control yawing the aircraft.

Miami Dutch roll • Oct 4, 2013 1:47:44 AM
I say it again AA587 was steady in the turbulent airflow before the unappropriate sharing actions on pedals. Miami is confirmed to have started as a dutch roll due to yaw A/P failure.

A real dutch roll is an OSCILLATION from one side to another with increasing bank due to resonance.

Despite you have a yaw movement in the dutch roll, the names says it well it s a ROLL oscillation, to be corrected with the stick not with pedals.

Don't confuse dutch roll with a low prestall flight that you control with rudder. A stall probably will evoluate to a spin on one side not with that bank oscillation from one side to the other.

Spiral is another situation with bank on a single side.

Lazy eight is already a little different : the dynamic oscillation is present but stays on the step of resonance. The flight remains not really unstable.

In the dutch roll the pilot has a very active role when he flies as learned.

Controling a dutch roll gets really scabrous if you feed his closed loop with energy: and we know that reserves of energy are unlimited so long te plane is not on the ground and stopped (potential and kinetic energy). If you "play" a little more with oscillations or configration or thrust, you continuesly tansfer energy bags... that is very bad! If you know nothing about dutch roll, but have identified it, and have some room under you, the best is to put feet on the ground and hand on the knees : not very easy for a pilot in emergency!! If you are near of the ground, first go around, get altitude...
I suppose you had already applied oscillation abnormal procedure (yaw damper off/alt probably).

Using only the half, or 20%, of the control is not sufisant to overcome quickly a dutch roll. You have to use controls as some exact moment and at exact speed, after you leaved an exact number of seconds action on controls.

The dutch roll closed loop may be controled if you do not pull your plane in furious dynamic. Help the plane to find back quietly his first (!!) order natural oscillation (stopping to shake it!) , don't try to compute in your head when piloting an emergency a second, third, fourth degree system you builded yourself by that shaking : it is just impossible.

Let us jump here equations which don't figure in the well known n/speed stall and gusts enveloppe. But sailors know something looking like dytch roll, the French name is "roulis rythmique". Another similar dynamic is that of the toreador : banderillas are used to oblige the animal to use only first degre movement.

The dynamic of the dutch roll affects not only the position and attitude and bank of the dutch rolled pkane, but also the airflow around the plane, resulting in the very strong effect catching the plane as in a net and doing very difficult some movements. Miami report shows that phenomena which has to do with our bad knowledge of ..theory of lift.

AA587 wasn't a dutch roll. It started with wake turbulence and ended up with rudder movement causing the VS to fail. The question is was it pilot induced or did the airplane do it. I believe the airplane did it. Our MIA incident at their speed if repeated could be why it happened. I think the FDR actually measures the rudder movement, not pedal movement so would like to see the read out of the MIA incident vs JFK crash and compare them. MIA, the pilots couldn't move the rudder pedals but JFK it shows full deflection. Did anybody ever bother to compare them? Probably not. If I was in the NTSB I would because the FO is being blamed for what the rudders did but I don't think he pushed the rudders, the A300 systems did again. I could be wrong but I don't think so.

Something I'm finding very disturbing about this thread is the suggestion/implication that the NTSB and FAA are incompetent or corrupt. I'm wondering how many of the people making these suggestions have actually dealt with the FAA during an aircraft certification, or worked with the NTSB during an air safety investigation?

Having done both (I became a DER 25 years ago and I've been involved in multiple air-safety investigations), I find the implications insulting to those involved. My experiences have been just the opposite - people obsessed with covering every possible detail, with impeccable ethics and integrity.

Bubbers, do you honestly believe no one in the NTSB considered the possibility that the rudder movements were uncommanded, and looked at data/research that convinced them otherwise? Does Teldorserious really think that they faked the data that said the tail failed at 2.2x design load (well above the FAR mandated 1.5x)? These are not mindless government agencies we're talking about - they are real flesh and blood people. People that know that other peoples lives literally depend on them getting it right.

Now, that doesn't mean I always agree with the FAA/NTSB - heck I can think of times when the FAA and NSTB couldn't agree with each other, and even times when different branches of the FAA couldn't agree with each other. But these fell into the realm of honest differences of opinion between engineers - something that happens with some regularity between even the best engineers.

So, before you make another post slandering these people, you might want to think about what exactly you're posting.:ugh:

As for aircraft design parameters that would allow a pilot (or terrorist) to break an airplane tail on purpose, it seems to me that a pilot (or terrorist in control of an aircraft) has the ability to intentionally crash an airplane pretty much any time they want, no matter how strong we make the tail :mad:

tdracer – Please accept my compliments for a well worded and very well positioned post.

There are some here who are somewhat more knowledgeable about some things whereas others may not be – and that’s simply a fact of life. Throwing insults at peopole or organizations just because the work they do may not be understood or appreciated – is the height of ignorance spiced with laziness. Thanks for bringing a level head to the table.

As I’ve been trying to convince some here, this accident was NOT caused by the wingtip vortices generated by the preceding JAL747. Yes, that preceding airplane did generate wingtip vortices – and yes, AA587 encountered both of them. The first encounter was handled professionally and rather easily by the pilot flying (the F/O) and his response was precisely what he was taught. However, the second encounter was not handled well at all … and it was contrary to what he had been trained to do. He was trained - and he did perform correctly … the first time. The question should be, why did he do almost the opposite of what he had just done very successfully?

Additionally, there are some here who stubbornly hold to the concept that the rudder displacements – clearly seen on the FDR – were a result of the vortex encounter – not rudder pedal inputs. HOWEVER, as I’ve also been trying to convey to these folks, the rudder was displaced by the pilot flying – and done deliberately (and could easily be described as a “panic” response – which is what I believe caused him to respond so distinctively different from the way he had just responded to exactly the same kind of stimulus) all of which were excessive, and most of which were at - or beyond - the control limits … and reversed each of those inputs at least 5 times in a 7 second period. And, before those same naysayers jump on this issue claiming that rudder pedal position is not an FDR parameter – YES IT IS. While it wasn’t originally installed on the A300-600 at construction, American DID install a modification (to be in compliance with the requirement that was to soon become effective) that recorded the control wheel, control column, and rudder pedal positions on the FDR. And NO, these are not back-driven controls – and that is the reason for the requirement for the completing the FAA-mandated modification … to be able to record those control position inputs as well as the resulting control surface positions. The FDR clearly shows that the rudder pedals were used to command the rudder surface position. In fact, the NTSB had produced an animation of the FDR readouts showing the cockpit controller positions (column, wheel, and pedal) as well as rudder position with superimposed markers showing the relevant control limitations that adjusted as airspeed increased. I used to have a copy of that animation but I don’t have it with me. Perhaps some here may have or know how to acquire that animation – it shows what happened quite clearly ... and it is quite sobering.

As many have said here … I, too, get no satisfaction out of criticizing another aviator – but facts are facts – and we can choose to ignore them or examine them. Personally, I’d prefer to examine them and learn, if we can, why a well-trained aviator could become so easily panicked as to do what this well trained and otherwise competent aviator did.

Sure, we can criticize training programs ... and simulators ... and instructors all day – but unless we know the facts – such criticisms are simply howling at the moon – a lot of noise, drawing some attention, and accomplishing nothing.

So, how do you explain this:

This is a verbatim quote from a revision to the US Air Force's KC-135 operating manual.

The KC-135 is a *Boeing*

This revision was published on 30 June 2000.

That was more than a year before the AA587 crash.

OK, once again; this has been addressed before and either you missed it or you're ignoring it because it doesn't fit with your theory.

The FDR records position of *both* the *rudder* and the *Rudder pedals*

The FDR positions from the accident of *both* the Rudder and rudder pedals agree.

The Yaw Damper acts through an averaging mechanism which prevents yaw damper movements from moving the rudder pedals.

If the yaw damper moved the rudder, the pedals would not have moved

The rudder pedals moved.



Even though that is contradicted by all the evidence.

It measures and records *both*

Yes, the NTSB did

Yes, the NTSB did

They did


Sorry to keep repeating, but this has all been posted before. How many more times does this have to be repeated before you read what is being posted?

A Squared. Stop being so nasty to Bubbers. His belief is that all American pilots are infallible. :rolleyes:

Who are we to question that fallacy?

bubbers

One has to admire your tenacity in defending your colleagues, but I fear you are now clutching at straws. As has been said several times both pedal position and rudder deflection were recorded and reported. This is an extract from the Performance Group's appendix to the NTSB report - sorry I don't seem to be able to make it smaller.

roulis

Dutch roll is certainly an oscillation, but it doesn't have to be one of increasing bank; in fact it would be a lousy aircraft for which that were true - very probably unflyable. Increasing bank as a result of suitably (mis)timed pilot inputs is quite another thing.

Sure the rolling motion is usually the most obvious sign of a dutch roll, but the motion is a combination of two oscillations - one around the roll axis and the other around the yaw - linked together by a common driver - sideslip.

Way back in the 1950s Ashkenas and McRuer established the importance of the roll/sideslip ratio as a parameter to describe the goodness/badness of dutch roll. The larger the number the worse the aircraft basically. So dutch roll can be triggered by rudder application, but as you say it is best controlled by aileron.

So far as I know, the A300 was not noted as having poor dutch roll characteristics.

Nope, in investigating an accident resulting from rudder movement, it just never occurred to the NTSB to examine part of the autopilot which actuates the rudder.

That's sarcasm. Of course they examined the a/p rudder actuator. The clutching mechanism was disengaged. Read about it in Addendum #5 in the Systems group Factual Report.

I usually keep l out of conversations involving either AA587 and TWA 800:ouch:

Hear! Hear!

LSM,

I trust you meant American Airlines pilots are infallible. Lots of us mere mortal American pilots make mistakes, sometimes, with a blue moon shining. :cool: :}

Although it hasn't been specifically referred to on this thread, there does exist a group of pilots - mostly of a certain generation - who retain a degree of hostility to the NTSB because of the TWA "Hoot" Gibson case. The NTSB made a judgement call there that with 20/20 hindsight could be considered shaky at best - however not only was this almost 35 years ago, but also the call was made due to a lack of hard data because of the primitive nature of the FDR. As has been pointed out, the FDR on AA587 was much more advanced and recorded the relevant parameters separately.

Putting that case in historical context, it can be seen almost as an aberration - as in accident reports both prior and following, the NTSB (post-separation from the FAA) showed no significant bias towards one party or the other.

Much the same could be said of the French BEA and AF296 (except in that case they made the correct call, but it didn't end the controversy).

I know of only about five people who even know of Hoot Gibson (that one, not the SW one).

Acknowledging Dozy, who are the other 3?

I meant of the people I've flown with.

Thanks Dozy - I had to Google that one (the only "Hoot" Gibson I knew of was the Space Shuttle pilot - I have a SS model around he that he autographed :)).

After I found the Wiki, I vaguely remember hearing about that incident (I was a young, fresh faced engineer at the time) but didn't know it had become so controversial. There was a story going around Boeing at the time that the crew "accidentally" erased the voice recorder after landing (no idea if it has any truth). Doesn't sound like the NTSB's finest hour :rolleyes:.