Airbus Blames AA For Crash

[Ty Webb]

I have never flown the MD80, but it is my understanding that on the B717 (basically a DC9-32) that the rudder limiter ("porkchop") limits rudder travel, and I am assuming that the hydraulic back-up does the same . . . . . . . ?

As for the NTSB . . . . everyone likes to talk about rudder "inputs", but how do we know that the rudder "inputs" weren't really caused by the vertical stab twisting? I would be curious if this is possible.

 

[mckpickle]

Wasn't the captain in the lav doing the FA during most of the hold?? I remember reading something about that in the final report.

(Inset Porn Music Here!) While I'm not sure of the "reason" for his trip in the back, he had just returned and there was some speculation as to whether or not he was belted in when the roll upset occured. Now don't hold me to this but it is also unclear if both pilots were trying to pull it out because the A/C got a pitch disconect which only happens after ....ah...(foggy memory) I think a 115 pound difference in control colum input. But there was enough force to rip the tail clean off as they tried to pull out. Of course doing 350 knots and out of control might have had something to do with it! Poor basteds!

 

[metrodriver]

Ty, I think that's not very likely. Hydraulics by nature move easily one way, but very difficult the other. Most systems have an artificial feel system, simply because the actuators will not give you the correct response. If you move a control one way, the only way for it to return is if you make a control input the opposite way. I could see a problem with the rudder limiter-if it only limits pedal travel, or pilot input counteracted by the yaw damper. I don't know if the A300 has a rudder split in 2 pieces, with only one piece hooked to the yaw damper. I can see a situation where pilot input moves one pice, and the yaw damper moves the other piece the opposite way. The yaw damper works independant from everything. If it senses any yaw in the plane (whatever the reason) it will try to correct this.
Maybe VMA214 can shed more light on this.
Concerning FBW: in a lot of conventional planes you can select CWS (control wheel steering) on the autopilot. All control inputs will go through the autopilot system to the controls, effectively giving you FBW. Using this might give you more protection, and is an excellent substitute for manual cables. If I'm correct a DC10 could have been saved in the late '60's-early 70's when the floor collapsed, rendering control cables inop. If the crew had had CWS on, they might have been able to control it (wires ran through the ceiling).

 

[dsee8driver]

Hmmm..

VMS said:

3. The vertical stab/rudder assemblies on Air transport aircraft are certified for ONE full deflection of the rudder followed by a return to center. THAT is it!!! These airplanes are not certified for a rudder doublet and certainly not a triplet which is what occured on this airplane when the rudder finally departed the airframe. Engineering analysis has shown that almost any other air transport airplane out there, save maybe the 727, would have also lost the vertical stab/rudder assembly under the same conditions.

VMA, I'm not questioning your response at all. I would like some info on where you came up with it to follow it up a read a little more on it. All along we are thought that below VMA you can use FULL control delfection and never has there been any talk of a limit.

Thanks
Dsee

 

[typhoonpilot]

dsee8driver:

Boeing has put out a Bulletin. For your DC-8, it would be Bulletin No. DC-8-02-01 that is an excellent explanation of rudder design, load limits, and usage in modern transport jet aircraft. It is a rather lengthy piece full of technical detail written by a very sharp test pilot in Long Beach.

" 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 manuever... Boeing airplane vertical fins can also sustain loads if the rudder is rapidly returned to neutral from 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 manuevering speed.

Ty:

For the 717 here is some engineering info on the rudder. Typical V1 ( 135 KIAS )

Pedal Force 75 lbs., Pedal Travel 3.3", Rudder deflection 29 degrees

250 ( KIAS )

pedal force 65 lbs., pedal travel 1.6 ", Rudder deflection 13 degrees

Mmo

pedal force 40 lbs., Pedal travel 0.5 ", Rudder deflection 4 degrees

American's Advanced Manuever Program or whatever they called it by Captain Van Derberghe ( Sp? ) was very informative and I quite liked the videos but it was based on information applicable to military fighter aircraft not modern Jet Transports. Boeing and Airbus both freaked out when they saw what was being taught to the American pilots in regards to rudder usage during unusual attitude manuevers. As a result it is my understanding that the program is no longer being taught. Perhaps VMA214 has better info on that as it appears they have changed recently.

Typhoonpilot

 

[ksu_aviator]

Just one question, was the aircraft below maneuvering speed? If so, then rudder inputs, as harsh as they are allleged to be really should not be an issue

I remember hearing shortly after this incident that aircraft are only tested to one full deflection from center. Not full travel from one side to the other and not repeatedly. So, 7 rapid full travels would far exceed the testing that Airbus did.

Why it traveled 7 times from side to side is probably an unaswerable question.

 

[redd]

Maybe this will shed some light on what happened.

Here are the links to the NTSB reconstruction of AA Flight 587, the DFDR data and performance data combined w/the CVR recording on Media Player:

http://www.ntsb.gov/events/2001/AA587/NTSB_reconstruction587.wmv

And this is the NTSB web page it’s found on:

http://www.ntsb.gov/events/2001/AA587/anim_587.htm


I first saw this reconstruction back in November, I want to caution you, it is heart rending to watch, it made tears come to my eyes when I first saw it.

Their speed was 239 kts, higher than earlier posted in this thread, and they were climbing. You see calibrated full rudder deflection 5 times, occurring slightly after violent yoke movement.

About a month ago, I had a conversation with an AA, A-300 pilot about the rudder deflection depicted in the reconstruction, and he said to me, that full deflection was what they were taught at AA, similar to military fighter a/c. (Exactly what Typhoonpilot says above.) I even argued with the AA pilot about it, that they couldn’t possibly, but he stood his ground, he insisted they were taught that.

I still find it hard to accept that it was pilot error, the final results are not in, I keep hoping that it wasn’t.

 

[trainerjet]

I remember watching this reconstruction during the NTSB hearings where they were questioning representatives from Airbus.

I don't doubt that the AA Airbus pilot (although I'm sure you meant to say AA A-300 pilot...they don't operate A-320s) was correct in stating this is what they were taught. Their training program has come under scrutiny and criticism by the NTSB on several other accident investigations.

 

[B190Captain]

I'm not sure you know all the facts of this crash. While it was found that moving the de-ice boots aft would help, the crew was the more to blame in this. They were holding at a very slow speed in a 72 with flaps at 15 while in SEVERE icing. It was determined that no aircraft could have withstood that same icing. And they held in it for 30 minutes. I have seen sick amounts of ice on ATR's but only long enough to get out of it. In contrast the Emb-120 has had more icing related incidents than the ATR but prehaps since only 30 people can die instead of 70 the media doesnt care as much. But lets not forget one of the big reasons this gained so much attention was a book titled "Unheeded Warning" by Stephen A. Fredrick in which he provided the media with mass histeria about the ATR. Bottom line; the pilots did not understand the danger they were in and hence didnt avoid it.

I know only from what the NTSB had reported on the accident. I am not ruling out the fact that the crew may had a degree of responsibility but when Aeorspatiale was notified that some flaw may exist they said the only fault lies with the pilots.

On another subject relating to french aircraft manufacturers:

A couple of years ago I saw a documentary called "Survival in the Sky" on the Discovery Channel. It was said companies like Airbus build aircraft for the goal of removing the pilot entirely.

A senior pilot from Lufthansa commented that Airbus aircraft deprive the pilots of a sense of touch or feel for the aircraft when it's under automation. The joystick does not move nor the thrust levers move when the aircraft is flying on it's own unlike Boeing products. Boeing bulids aircraft by pilot input in many areas and when flying under automation the pilot can determine what the aircraft is doing just by touching the yoke.

The French don't give a rats @$$ about the pilots so who are they to blame when a superior french product becomes a hole in the ground?

I have no personal experience on the bus but know some that do and do not like'em very much. Don't get me wrong, I may prefer Boeing but will fly a bus if I had to.

Fly Safe!

 

[VMA214]

don't doubt that the AA Airbus pilot (although I'm sure you meant to say AA A-300 pilot...they don't operate A-320s)

Hey TJ, Dude...an A-300, last time I looked, is just as much an "Airbus" as an A-320.

The joystick does not move nor the thrust levers move when the aircraft is flying on it's own unlike Boeing products.

While this may be true of the "fly by wire" Airbus' it is not true of the A-300 which is NOT fly by wire.

About a month ago, I had a conversation with an AA, A-300 pilot about the rudder deflection depicted in the reconstruction, and he said to me, that full deflection was what they were taught at AA, similar to military fighter a/c.

I don't know who told you this and I guess this is what "concerned" people about this training, BUT, having undergone AA unusual attitude training NEVER ONCE did ANY Check Airman ever say anything to me about using FULL rudder to help bring the nose toward the horizon. The words I always heard was "use a "little" rudder to help get the nose moving toward the horizon. From what I saw, they were VERY careful not to imply that "full" rudder imputs were to be used. However, people and their ability to "hear" what they want to hear will probably tell you that this is NOT what they heard.

Also, having flown "tactical" jets (A-4s) rudder usage at relatively LOW airspeeds and HIGH angles of attack is not so much a "fighter" "technique" as it is a technique to be used on "swept wing" airplanes. And under those conditions (low A/S, high AOA) one would still NOT use FULL rudder authority either in a fighter or transport A/C. I'm not saying that NO check airman ever said to use "full" rudder but that I never heard it used!

Fly Safe!!