Interesting note about AA Airbus crash in NYC

[misd-agin]

Std climb profile. Seen the same profile used by other U.S. domestic carriers.

Gets you clean (less gas), and leaving town faster(less time).

AAMP never advocated 'kicking' the rudder which is an unfortunate term others have used. The AAMP tape, referenced in the NTSB report, actually says to be careful using the rudder at low airspeed and high AOA. "Too much is actually the spin entry technique, isn't it?"(paraphrased)

[Zeke]

From an excerpt from the 777, "Use of Rudder on Transport Category Airplanes", in response to NTSB Recommendations.

Explain to Flight Crews that a full or nearly full rudder deflection in the opposite direction, or certain combinations of sideslip angle and opposite rudder deflection can result in potentially dangerous loads on the vertical stabilizer, even at speeds below the design maneuvering speed.
Response: Boeing airplanes are designed to withstand the structural loads generated by a full rudder input out to the airplane's maximum operating airspeed, Vmo/Mmo. Some Boeing airplanes meet these requirements out to the design dive speed. This means the structure has at least a 50% safety margin over the maximum load generated by this kind of maneuver. As previously mentioned, Boeing airplane vertical fins can also sustain loads if the rudder is rapidly returned to neutral from the over yaw sideslip or the rudder is fully reversed from a full steady state sideslip. Boeing airplanes are not designed to a requirement of full authority rudder reversals from an "over yaw" condition. Sequential full or nearly full authority rudder reversals may not be within the structural design limits of the airplane, even if the airspeed is below the design maneuvering speed. There are no Boeing Procedures that require this type of pilot input. It should also be pointed out that excessive structural loads may be generated in other areas of the airplane, such as engine struts, from this type of control input. In addition, large sideslip angles may cause engine surging at high power settings.
It is important to note that use of full rudder for control of engine failures and crosswind takeoffs and landings is well within the structural capability of the airplane.

Originally Posted by misd-agin

AAMP never advocated 'kicking' the rudder which is an unfortunate term others have used. The AAMP tape, referenced in the NTSB report, actually says to be careful using the rudder at low airspeed and high AOA. "Too much is actually the spin entry technique, isn't it?"(paraphrased)

From the 777 manual

Boeing recommends that:
· Transport pilots should be made aware that certain prior experience or training in military, GA, or other non-transport aircraft that emphasizes use of rudder input as a means to maneuver in roll typically does not apply to transport aircraft or operations.
· Transport pilots should be made aware that certain prior experience or training in military, GA, or other non-transport aircraft types emphasizing the acceptability of unrestricted dynamic control application typically does not apply to transport aircraft or operations. Excessive structural loads can be achieved if the aircraft is maneuvered significantly different than what is recommended by the manufacturer or the operator's training program.
In simple pilot terms, 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.

Seems AA does not agree with what even Boeing recommends.
And ..

Q. What pilot action should I take to recover when I encounter wake turbulence?
A- Normal piloting actions for roll control are sufficient for large commercial jet transports. If a roll off does occur, the normal use of ailerons and spoilers should be sufficient to recover. The use of rudder is not recommended.
The induced roll from the vortex will be more severe for short span airplanes (relative to the aircraft that generated the vortex) but the recovery procedures are the same. Crews should perform the upset recovery procedures if bank angles of greater than 45 degrees are encountered.

[bomarc]

I think one thing we might all agree upon is this:

Insufficient information to the pilots regarding the possibility of rudder induced structural breakup was NOT part of either the Airline training program or the Flight Manual. Both approved by the FAA.

We might also wish to include in future FAA ATP written examinations a question concerning rudder induced structural breakup.

There have been other crashes where information existed in one location but not in another.

I am reminded of an F28 crash due to ice/frost on wings in Canada, only to be followed by a crash at New York's LaGuardia airport of another F28 due to ice/frost on wings.

Sharing information in the civil sector is vital.

[aardvark2zz]

Originally Posted by Graybeard

Here's a curve that maybe wasn't considered before:

The HF antenna and antenna couplers are in the leading edge of the vertical fin in most modern transport aircraft. It is a shunt antenna which is fed by the coupler that converts transmit power up to 400 watts at 50 ohms impedance to very low impedance - on the order of ten milli-ohms. The current, therefore, is very high, and it is carried a short distance from the coupler to the vertical fin on a heavy copper cable. The coupler excites the fin and makes the whole airplane into the antenna, meaning that very high currents are flowing in the vertical fin and its junction with the fuselage.......

It's 0 ohms near 0 Hz (DC) but once you get to a few hundred KHz the impedance is much higher. Don't forget that you have real and inductive impedance which 'add' up. 400W into 50 ohms is only 2.8A rms.

[Graybeard]

Originally Posted by aardvark2zz

It's 0 ohms near 0 Hz (DC) but once you get to a few hundred KHz the impedance is much higher. Don't forget that you have real and inductive impedance which 'add' up. 400W into 50 ohms is only 2.8A rms.

Maybe you've never seen the battery cable sized conductor from the center conductor of the coupler mount to the tail structure. That wouldn't be needed if the currents were low. The purpose of the current-fed antenna coupler is to convert 50 ohm impedance signal to near zero ohms - at operating frequency. That means currents up to hundreds of amps. And, yes, the carbon in a carbon fiber structure can mean mischief.

The HF system was undoubtedly thoroughly tested at A/B, but how about with all the combinations of degraded bonding?

BTW, what is 'real' impedance?
GB

[ssg]

Silly Thread

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested. What about windshear, wake turbulence, flying over smoke stacks, through the tops of some small cell, all could impose way more loads then just shoving the rudder over......

Is it possible a pilot could yank and bank a plane apart, sure, but with the captain sitting right next to him? On take off?

Funny no one is talking about composites, inability to test them at the time, ect.

Food for thought....

[bubbers44]

Sten went to max power in an escape maneuver before the last breakup of the airplane. when control was lost. He would not have done this at that speed of 250 knots unless all other methods of controlling the aircraft had failed with the captains concurrence. Hopefully some day he will be found not responsible for this accident but Airbus and others want to leave the probable cause just as it is, pilot error. No cost.

[bubbers44]

Remember, that aircraft had a delaminated vertical stab that was repaired with staples and the break was parallel with the staples holding the stab together. Seems a lot like holding a sheet of plastic in a vice and guess where it breaks? Parallel to the vice jaws where it flexes. That is how the new aircraft was delivered to American when it was new. Unfortunately Sten had to fly it when it flexed a few thousand times.

[DozyWannabe]

Originally Posted by ssg

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested. What about windshear, wake turbulence, flying over smoke stacks, through the tops of some small cell, all could impose way more loads then just shoving the rudder over......
Is it possible a pilot could yank and bank a plane apart, sure, but with the captain sitting right next to him? On take off?
Funny no one is talking about composites, inability to test them at the time, ect.

But it was more than just a rudder over, ssg. It was repeated contrary motions, in a sideslip, following a wake turbulence event. I don't think anyone would risk flight testing that situation knowing what we now know about it.

If the jury was out on composites, and it was obvious that Airbus made a mistake in using them, there's no way that Boeing would be risking their future by building their next big project completely out of them - at least, one would hope not.

It's in the nature of people to defend their own in such situations, and if the findings were as cut and dried as blaming the pilot for overcontrolling then I could understand the desire to dig deeper. But it's not that cut and dried, is it? There was a training culture that was too all-encompassing when it came to the type being flown - contributory cause number one. There was a bulletin that was disregarded regarding use of rudder in upset recovery - contributory cause number two. There was a pilot who, while doing as he was apparently trained, overcontrolled the aircraft and overloaded the tail - contributory cause number three. No-one is (or more precisely should be) blaming Sten Molin for what he did, which was by most accounts exactly what he was told to do. I hate to say never, but I doubt that the captain was monitoring his rudder inputs at the time - there simply wasn't the time to figure such things out. The system failed the people on that aircraft and the system has since been changed. There are those that want to blame Airbus and there are even those that insist that there was an act of terror involved. None of this is helping our skies be safer.

[bubbers44]

The captain always monitors unusual control inputs by the copilot. Those inputs would have probably killed a standing flight attendant in the back who got up to take care of a passenger in distress right after takeoff. I do not think you could put enough rudder into an A300 to rip the engines off. The vertical stab must have done it. It probably was separating from the aircraft causing the gyroscopic forces on the engines to make them separate from the aircraft. Wake turbulence normally does not cause much yaw and is easily corrected by aileron. Has there ever been a wake turbulence upset causing extreme yaw? I have never encountered one.

[TowerDog]

I'm sure it's American airlines SOP,i've just never seen a profile like it.
Climb power 1500ft agl, accelerate 3000 agl. is all i can recall on many types in 22years.

That would be Noise Abatement Climb profile.
Quite a few US companies go for clean machine at 1000' unless a Noise Abatment profile is called for.

As for the topic on hand:
I have been through the AA course recovering from unusal attitudes. There was nothing there about slamming the rudder from side to side, but rather using "top" rudder to help bring the nose around...If needed.

Keep in mind the A-300-600 that crashed had the vertical tail damaged at the Airbus factory before delivery to AA.

Perhaps a factor in the accident....?

[INLAK]

Having flown with African, Asian, Australian, European and American pilots, I found a very noticable enthusiasm to use the rudder from the Americans only. Maybe it's all down to training.

[Mad (Flt) Scientist]

Originally Posted by ssg

Come on guys, he wasnt going that fast, wasn't near VMO. If a plane comes apart at slow speeds with a rudder imput, not talkin elevator here, then I think that plane might need to be flight tested.

I am frankly astonished that after all the warnings which were issued after this accident, regarding the potentially catastrophic effect of large rudder inputs AT SPEED EVEN BELOW VA, that anyone could dismiss the idea that rudder inputs could overload a transport category aircraft with such disdain.

Every single Part 25 aircraft with conventional flight controls (i.e. disregarding those with envelope protection) can undoubtedly be brought to the point of inflight break-up by means of flight control applications, even at speeds comparable to this accident. The only differentiation between types is the degree of input (or number of inputs) required, and the associated cockpit forces. But they WILL all do it.

In fact, any aircraft claiming to be resilient to such inputs is in fact BADLY designed, because there was - and still is! - NO certification design requirement to withstand such inputs. And I suspect there never will be; it's not the intent of the regulations to specify a pilot-proof aircraft, simply one that can be operated safely if trained accordingly.

[DozyWannabe]

Originally Posted by bubbers44

I do not think you could put enough rudder into an A300 to rip the engines off. The vertical stab must have done it. It probably was separating from the aircraft causing the gyroscopic forces on the engines to make them separate from the aircraft. Wake turbulence normally does not cause much yaw and is easily corrected by aileron. Has there ever been a wake turbulence upset causing extreme yaw? I have never encountered one.

What you're describing are the precise conclusions of the investigations - the rudder reversal induced vertical stab separation, which induced yaw and spin, which induced engine separation.

Originally Posted by TowerDog

Keep in mind the A-300-600 that crashed had the vertical tail damaged at the Airbus factory before delivery to AA.
Perhaps a factor in the accident....?

Got a link handy for that? 'Tis the first I've heard of it. I think there was some disbonding, but that was unrelated to the failure and could be considered normal wear and tear.

[hetfield]

Originally Posted by INLAK

Having flown with African, Asian, Australian, European and American pilots, I found a very noticable enthusiasm to use the rudder from the Americans only. Maybe it's all down to training.

Yeah, I fully agree with you. When I started flying on a Bonanza, my instructers (all of them american) made comments about that bungee which operated (within certain limits) the rudder without pedal inputs........

[Slats One]

The case of the ageing composite and so much more

Having just spent a long time researching composite construction, I want to throw an unpopular theme into the debate.

Even if we put aside that this aircraft was flying with a manufacturing "cure" fault repaired, there is now surely enough hard evidence - ie the Transat rudder disintergration etc, to now conjecture if there is another reason why the handling pilot was pumping the rudder pedals?

We have been asked to accept that pilot's behaviour, the AA advanced handling training, etc, were the fulcrum behind the handling pilot's response to a wake turbulence induced issue - which then led to the empenage snapping off as a consequence of pilot induced oscilations.

Sorry folks, I no longer buy it. What if the reason the rudder pedals were being pumped was because (a la Transat event) the rudder had begun to disintergrate and detach - resulting in aerodynamic instability - leading to reactive pedal inputs - which are then erroneously blamed as a pilot error cause.

If you doubt the possibility of this potential scenario- go an examine the Transat investigations. You will find that not only did the rudder break up and tear off, it also almost severed the main fin mountings-one side had already begun to tear. It becomes obvious that if the Transat crew had reacted by pumping the pedals, the process would have been completed and another Airbus lost. But they were in the cruise not maneuvering a climb out form JFK.

And all this is without discussing the fitting of one tail design to range of fuselages with differing levels of thrust, polar inertia and airflow. Let alone ageing composites, manufacturing errors and repairs across the entire marque and the mulitple ADs issued about such. Throw in hydrualic actuattor leaks effecting bonding and lamination and electrical effects an you do not even begin to make a 'knock' test of the structure an effective tool.

Sorry folks, but I am not alone in worrying about the ease with which pilot error is being used to smother the very real issues of composites and how Airbus has chosen to use them. And no this is not an anti- Toulouse rant. Its careful factual analysis of a pattern of dysfunction within the design.

Speculation is dangerous, but a repeated pattern of events requires further investigation.

[misd-agin]

Originally Posted by DozyWannabe

What you're describing are the precise conclusions of the investigations - the rudder reversal induced vertical stab separation, which induced yaw and spin, which induced engine separation.


Got a link handy for that? 'Tis the first I've heard of it. I think there was some disbonding, but that was unrelated to the failure and could be considered normal wear and tear.

Find the crash photos from AA 587 and look at the pictures that show the tail. One segment of the tail is still attached to the fuselage lug attachements. That segment is the patch installed by Airbus to correct some production damage(incurred while installing the tail???). The patch was stronger than the rest of the tail.

Design failure is 2.00 design load(incorrect terminology). Failure occured very, very close to 2.00(+/-.3 I believe).

[JustAnothrWindScreen]

Originally Posted by Airbubba

Yep, this program filtered down to the other airlines. I was given a version of the training that included the hard rudder kicks to get the nose back down to the horizon in some attitudes. I questioned whether you really wanted to do this in a transport aircraft but was told that it was all within the design envelope. I guess it turns out that it wasn't...

I went through the AA program and it did not include hard rudder kicks for any maneuver. It did however include smooth coordinated rudder when necessary. .

[bomarc]

slats 1

I think you are right

[bubbers44]

Slats one, I have always thought your feeling that he was reacting to the aircraft yawing because the vertical stab or rudder was failing was correct. Did they study if the rudder inputs were before or after the aircraft yawed? I believe I read that the actuators on the rudder sends signals to the flight recorder, not the rudder pedals.