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He stepped on the Rudder and redefined Va

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He stepped on the Rudder and redefined Va

Old 25th Sep 2013, 23:31
  #21 (permalink)  
 
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Originally Posted by misd-agin View Post
It was three or four.
This.

Originally Posted by tdracer View Post
In the aftermath of the A300 vertical tail failure, Boeing evaluated what would happen with similar oscillatory rudder inputs on various Boeing airplanes. The results were not pretty
This!

Originally Posted by SMT Member View Post
As for the idea of the skipper stopping it .... with feet on floor, and 3 rapid rudder movements which his sensory system is likely to have overwhelmingly felt rather than seen, I think it would require reaction times far in excess of what is humanly possible.
*This!*

Originally Posted by bubbers44 View Post
NTSB has political pressure to blame the pilots, not the manufacturer, so blame goes to the low money people.. That is my opinion.
Based on what evidence? Plus, as I'm sure you know, TWA800 was not put down to pilot action.
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Old 26th Sep 2013, 02:29
  #22 (permalink)  
 
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Originally Posted by Pugilistic Animus View Post
...no airplane in existance will tolerate such oscillation ...
That covers a lot of aircraft. I believe that is an incorrect statement.
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Old 26th Sep 2013, 02:56
  #23 (permalink)  
 
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Just got back from the Reno Air Races and saw a lot of aircraft use full rudder deflection, granted one way, and flip end over end and came out inverted in level flight. I know these aren't airline aircraft but I think a vertical stabilizer is designed to take a lot of stress. Seems like the slipstream alone would make rudder reversals less stressful because the aircraft is trying to straighten it's fuselage with the slip stream automatically.

Remember our A300 came out of the factory with a patched VS so stresses were put on a very small area after the patch. They blamed the FO but as I said before no matter what that previous captain said about his rudder usage I think it was an airframe problem, either the patch or maybe another yaw damper malfunction.

If you take a piece of plastic and put it in a vice it doesn't take too many oscillations to make it break. That is what they did with the delamination, they braced it.
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Old 26th Sep 2013, 03:16
  #24 (permalink)  
 
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Oslander1 not even an Extra can take flight control reversals like that... ever hear of resonance?
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Old 26th Sep 2013, 03:20
  #25 (permalink)  
 
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TWA800 was controlled by the FBI and CIA according to the documentary and NTSB was pushed aside according to the 6 NTSB retired people who made up the documentary. They manipulated evidence, changed locations of wreckage found to fit their story. Witnesses of the missiles were ignored and the center fuel tank with the 3,000 ft climb explained the explosion. I know these pilots could not do anything but our government can tell any story they want to make their case and 90%of the people will believe it.

They need to reopen that investigation to tell what really happened.
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Old 26th Sep 2013, 03:33
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PA, resonance is a frequency of events because it expands at that frequency like the Electra problems they had at certain engine RPMs. Using rudders has no resonance unless it is a flutter like a yaw damper oscillation. A pilot can't do it.
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Old 26th Sep 2013, 06:26
  #27 (permalink)  
 
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PIO

I don't think the FO did that because the captain would have stopped him if he did. Would any captain let his FO do this? I wouldn't. We had an A300 have out of control rudder movements landing at MIA and both pilots felt they were going to crash prior to this event.
We have two very different situations :

- The flight AA587 was tooken in a heavy and quick wake turbulence and the first officer did that violent pedal sharing very quickly - probably the captain had feet on the ground and could not avoid his FO pedaling quickly enough. It is a non pilot induced big oscillation of the airflow where the A300-600 had a stable dynamic, followed by a pilot action near of shocks giving excessive conventional aerodynamic forces.

- In the both cases with Yaw damper failure, the possibility of DUTCH ROLL is important. You avoided it on your B727. Your friend and his Captain had less chance and developped the dutch rolll which is a resonance between the airflow movement around the whole aicraft and action with roll and/or rudder of the pilot to stop that PIO - inadequatly because the dutch roll is not taught to pilots nore described in ATPL books, where the problem is described as non existing with the yaw damper . But dutch roll may start by other initial disturbation - pushing one pedal violently (..in a sim is safer ) - and the pilot feeds himself the resonance acting on the stick and pedals AT THE WRONG MOMENT AND WITH INADEQUATE SPEEDS. A good aerobatic flight culture may avoid/correct that resonance without equation, but it may be solved, in flight, by equations too.

About the SOP, I already told that Learjet had elaborated that poor and dangerous method of rapid pedal sharing movements after years of fears and some accidents to try to stop their genetic dutch roll. As nobody around the world wanted to teach pilots about dutch roll and other PIO - labelled as "pilot FAULT" and sometimes "human factor" (sic) - in case unions would use it anyway, that bad bar SOP was used - around the world in our lovelly international community - against any unwanted oscillation and turbulence ,and perhaps applied in the Queens accident AA587.

Last edited by Jetdriver; 26th Sep 2013 at 18:15.
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Old 26th Sep 2013, 07:25
  #28 (permalink)  
 
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the four jet transports I've flown either had a rudder limiter or a placcard about control use. that plane would still be flying if it had a rudder limiter based upon speed.
All those jet transports have limiters which limit the rudder so that it is safe at any speed to apply one full rudder input. Reversals are destroying any of those aircraft.
some pilots, myself included, think the problem was not in the pilots/copilots feet.
I agree, the problen was most probably more at the top end of the pilot/copilot...
No pilot is a normal state of mind would think, that he can safely do several full elevator reversals at that speed. So why should full ruder reversals be OK? On the other hand, would any pilot is a normal state of mind reverse the rudder at a 0.3 to 0.4 second frequency?
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Old 26th Sep 2013, 08:42
  #29 (permalink)  
 
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I was taught from day one when flying large airliners that the rudder was for crosswinds and engine failures that's it, even in upset attitude training I was told to avoid using the rudder and this was 20yrs ago.

Also having been inside section 48 of the 747 and inside the fin I can assure you all it's not attached as securely as some people here seem to think. So don't go thinking it's some deficiency of Airbus, Boeing recommended exactly the same thing regarding rapid rudder reversals.

Photos: Boeing 747-206BM(SUD) Aircraft Pictures | Airliners.net

There are no spars running through into the fuselage it's simply bolted on top.

Last edited by SMOC; 26th Sep 2013 at 08:49.
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Old 26th Sep 2013, 14:00
  #30 (permalink)  
 
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Originally Posted by bubbers44 View Post
I think it was an airframe problem, either the patch or maybe another yaw damper malfunction.
You're entitled to that view, but that then begs the question of why a supposedly weakened structure did not fail until the load on it was almost double the Ultimate Design Load that the engineers had calculated. If anything the vertical stab and attachments were *stronger* than the designers thought - not weaker.

Last edited by DozyWannabe; 26th Sep 2013 at 14:01.
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Old 26th Sep 2013, 15:06
  #31 (permalink)  
 
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bubbers44, without getting into the contraversy of AA587, my only point is that cycling the flight controls is extremely dangerous...no airplane is meant to take it
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Old 26th Sep 2013, 15:28
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Roughly 30 years ago, while flight testing an E6 (a military version of the 707 with CFM engines), they suffered serious vertical tail damage. I don't recall what they were doing at the time (it may have been flutter testing but it's been a long time so the memory is fuzzy).

What's not so fuzzy is that I happened to see that airplane parked in a hanger at Boeing field shortly after the incident. Roughly half the vertical tail and nearly all the rudder were missing

I don't seem to recall anyone ever claiming that the 707 airframe wasn't robust.
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Old 26th Sep 2013, 15:38
  #33 (permalink)  
 
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Originally Posted by roulishollandais View Post
Your friend and his Captain had less chance and developped the dutch rolll
As I recall, the AA587 situation was not indicative of Dutch Roll as much as it was repeated sideslips in opposite directions.

Aircraft with wing-mounted engines require rudders with more control authority than those with tail-mounted engines because the adverse yaw in an engine-out scenario is much greater. To give an example, both the Air Transat and Gimli Glider incidents used a single sideslip to slow the aircraft down, and in the latter case, the Captain was concerned about what that sideslip would do structurally if it was held too long. As such, it was a last-ditch move.

Reversing a sideslip once, let alone repeatedly and in quick succession, will break any airframe eventually.

[EDIT : Additionally, if the yaw damper input was the source of the oscillations, it would have shown up in the FDR. ]

Originally Posted by tdracer View Post
I don't seem to recall anyone ever claiming that the 707 airframe wasn't robust.
You clearly never encountered the late 411A...

Last edited by DozyWannabe; 26th Sep 2013 at 16:16.
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Old 26th Sep 2013, 16:22
  #34 (permalink)  
 
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Both vs Two

Originally Posted by roulishollandais
two very different situations :

- The flight AA587 [...]conventional aerodynamic forces.

- In the both cases with Yaw damper failure [...] Dutch roll
Dozy,
It seems that my text was unclear : the both cases were Miami and Bubbers44's B727 flight and did not correspond to the two situations.
In my post I suspected a dutch roll as possible, in the Miami flight, and in Bubbers44's B727 flight (avoided by Bubbers44 aerobatics experience), and not in the AA587 flight.

The connexion I am asserting, between AA587 and dutch roll, is that AA587 used a unfounded and dangerous method, created against Learjet's dutch roll generalized to other oscillations too, as nobody worried about dutch roll and other oscillations. Telling about PIO experiences has during a long time been considered as totaly taboo (not sure it is finished).

In any situation that rudder pedaling is dangerous.

edit : add that PS : If you have a dutch roll, accept the yaw damper outputs as they are (adapted or failing, you can do nothing, only the ground), but only the pilot's input on stick and pedals can - and must - be modified and adapted to stop increasing that crazy oscillation (and high negative Vz) and stop the oscillation and stabilize attitude and path so much as possible (once more inertial data HUD may help).

Last edited by Jetdriver; 26th Sep 2013 at 18:15.
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Old 26th Sep 2013, 21:38
  #35 (permalink)  
 
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A view from history...

During the last 10 days of 2006 through the first 8 or 10 days of 2007, there was an extremely "inspired" (some might use the descriptive terms "emotional," "heated," or "impassioned") discussion on this very subject – and, as my memory serves, all of the points of view raised here were taken into consideration at that time – and I would presume would remain essentially the same today. Therefore, I see no particular advantage in attempting to repeat the rather lengthy posts I made during that time in this forum’s history. Suffice it to say that the F/O at the controls of that ill-fated flight made control inputs that no one can deny. Of course the speculation will continue as to the cause – poor airplane design – poor pilot training – an absence of knowledge of airplane certification processes – belief that some airplane manufacturers are more interested in covering “their 6” than speaking the truth – and on and on and on. I’m not sure of what kind of archives may or may not exist on this forum … but it might be worthwhile having those on this forum today read what was said during that 20-day period almost 7 years ago. Since that time, I have seen some major training adjustments and some significant changes in the pilot population having a much better understanding of the terms AND what those terms mean. However, there are some who will refuse to spend the time to read AND understand, believing that simply reading the material or relying on their own knowledge and experience will be sufficient. It’s those persons I would prefer to NOT fly with, thank you. We go through the process of accident investigation, not to fix blame, but to fix problems … when and where they may be found. If we get to the point that blame and consequences are more important than finding out what went wrong and attempting to find ways to prevent the same thing from happening again – I will feel as though the description of “professional pilots” will have to be changed simply to “airplane operators” – with no adjective included. That, to me, will be a dark day for all of us!
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Old 26th Sep 2013, 22:04
  #36 (permalink)  
 
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@AirRabbit - I remember it well. I believe there are some search tips (using Google) at the start of the AF447 thread that will get you the material. I'll have a go myself later.

Originally Posted by AirRabbit View Post
...belief that some airplane manufacturers are more interested in covering “their 6” than speaking the truth...
Well, the legal departments of *all* major corporations, be they manufacturer, airline or whatever will do that - they wouldn't be doing their job otherwise. That said, investigative authorities have become a lot better at sorting the wheat from the chaff in the last 25 years or so.

Agree with everything you said.
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Old 26th Sep 2013, 23:12
  #37 (permalink)  
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Oh gee wiz...anyone in here see acro planes, student trainers, even tprops and bizjets during training, people are standing on the rudders, back and forth all day long, year after year for decades...not one tail has fallen off..

What gets me is that the really funny kinds of accidents that defy logic seem to happen in Airbus's...

The only double engine failure ever due to birds?

The only crash where three pilots lose complete SA in level flight completely lost, right until the they impact the water?

The only tail coming off on departure at slow speeds?

Didn't some Afgani AB go down because the FO's seat slid back? Where was the captain?
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Old 26th Sep 2013, 23:32
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Originally Posted by Teldorserious View Post
What gets me is that the really funny kinds of accidents that defy logic seem to happen in Airbus's...
Really?

The only double engine failure ever due to birds?
Eastern Air Lines Flight 375 - Wikipedia, the free encyclopedia (Lockheed Electra - quadruple failure - fatal)
Ethiopian Airlines Flight 604 - Wikipedia, the free encyclopedia (B732 - double failure - fatal)

The only crash where three pilots lose complete SA in level flight completely lost, right until the they impact the water?
Birgenair Flight 301 - Wikipedia, the free encyclopedia (B752 - fatal)
Flash Airlines Flight 604 - Wikipedia, the free encyclopedia (B733 - fatal)
Northwest Airlines Flight 6231 - Wikipedia, the free encyclopedia (B722 - fatal)


The only tail coming off on departure at slow speeds?
See previous posts - Boeing determined that those inputs would have exactly the same result and changed procedures accordingly.

All manufacturers have their flaws and Airbus are no exception - but at least do your homework before making sweeping claims like that!

Last edited by DozyWannabe; 26th Sep 2013 at 23:41.
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Old 27th Sep 2013, 01:35
  #39 (permalink)  
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Dozy - Two things...do you really believe that if you took off any plane, on climbout that if you stood on the right rudder, then the left, then the right, the tail would come off? You should see what people do in aircraft...still here...

Secondly, I am just waiting for a Va placad to be put in planes...

Va-200kts

except if you push the rudder a little too much back and forth,at a non specific airspeed, and don't pull up or push down to much either because we don't test for full scale deflections either..so in summary, just don't move the controls, too much, at any speed, just to be safe.
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Old 27th Sep 2013, 02:42
  #40 (permalink)  
 
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Va is the maximum speed which any ONE of the flight controls can have a maximum deflection without exceeding design limit load... If other flight controls except the elevator are not limiting then Va is a function of stall speed and design limit load. This post is poorly worded...but even unlimited aerobatics champions don't reverse the flight controls rapidly they always unload first.

Last edited by Pugilistic Animus; 27th Sep 2013 at 02:53. Reason: typo
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