Canus Chinookus Posted June 15, 2009 Share Posted June 15, 2009 I would say they were in the middle of successfully navigating around some storms and maybe got too close and took a lightning strike(positive ly charged), blew out some electronics, kicked off the autopilot and depresurized the plane, and the pilots didn't get their masks on in time, or if they did, they lost their radar, and inadvertantly flew through a storm while electronically 'blind'. There's my guess. I just hope we find that black box and get the truth. Link to comment Share on other sites More sharing options...
bm330 Posted June 15, 2009 Share Posted June 15, 2009 one of the ACARS messages was Rudder Limiter Fault. The Rudder Limiter on the Bus has different modes depending on the airspeed. At low speeds - lots of authority , high speed - not so much. The message gets triggered when the flight computers dont know what the speed is. Along with the other messages, it points more towards the pitot / unreliable speed scenario rather than turb encounter (at least initially). Link to comment Share on other sites More sharing options...
Guest rattler Posted June 15, 2009 Share Posted June 15, 2009 another view of the VS. http://www.foxnews.com/images/538477/2_28_...ir_france01.jpg Link to comment Share on other sites More sharing options...
boestar Posted June 15, 2009 Share Posted June 15, 2009 The Rudder Limiter on the Bus has different modes depending on the airspeed. At low speeds - lots of authority , high speed - not so much. The message gets triggered when the flight computers dont know what the speed is. Along with the other messages, it points more towards the pitot / unreliable speed scenario rather than turb encounter (at least initially). Actually I never thought of it that way but you are correct. Logic would dictate that if the airspeed is unknown that the Rudder would be full authority with a warning indicating as much. This would be the Fail Safe condition. But (and this is just speculation and nothing more) if the pilots were busy trying to handle a damaged or otherwise broken aircraft and did not notice the message and were using inputs to the rudder that would be normal at cruise speeds they could actually have been making larger OUTPUTS than intended. Still waiting for the Black Boxes to tell the story. Link to comment Share on other sites More sharing options...
Guest rattler Posted June 15, 2009 Share Posted June 15, 2009 Yahoo news has a lot of pictures of the debis and in particular some showing more detail of the VS root (shearing area) http://news.yahoo.com/nphotos/Air-France-j...4ca4ed1e0e5c543 Link to comment Share on other sites More sharing options...
Seeker Posted June 16, 2009 Share Posted June 16, 2009 Just out of curiosity, what kind of rudder inputs are "normal" at cruise speed? None. Link to comment Share on other sites More sharing options...
handyman Posted June 16, 2009 Share Posted June 16, 2009 None. I think he was trying to solicit a more interesting answer! Link to comment Share on other sites More sharing options...
hollywud Posted June 16, 2009 Share Posted June 16, 2009 He probably was, but the answer is nevertheless correct. I can't imagine a scenario other than the aircraft being in an unusual attitude where rudder input would be necessary. Link to comment Share on other sites More sharing options...
boestar Posted June 16, 2009 Share Posted June 16, 2009 He probably was, but the answer is nevertheless correct. I can't imagine a scenario other than the aircraft being in an unusual attitude where rudder input would be necessary. That was my point, if rather poorly stated. If the aircraft was in an unusual attitude and use of the rudder was required, the fact the t the rudder limiter had failed would mean that fulldeflection of the rudder was available. So a full press on the pedal would give you full deflection. If the airspeed was in fact high then this is a bad thing. If the aircraft was slow as has been suggested in the media then not so bad. All I am trying to say is that a rudder limiter failure would mean that the rudder would give full deflection. This is (can be) a bad situation to the point where forces induced by the rudder could tear the Vertical Stab off of the aircraft. We have seen this on another Airbus type aircraft. Again this is pure speculation and looking at one possibility. Link to comment Share on other sites More sharing options...
Maverick Posted June 16, 2009 Share Posted June 16, 2009 None. yaw damper? Link to comment Share on other sites More sharing options...
Pivot Posted June 16, 2009 Share Posted June 16, 2009 Just to clarify, the other Airbus type (A300) that lost its vertical stabilizer was not a result of the application of full rudder. It happened because of a reversal from full rudder deflection on one side to full rudder deflection on the other side. Can they be 100% sure that in the A300 vertical stab failure the stab was not breaking off before the full rudder deflection was recorded? I still have a hard time believing that the pilots were banging on the rudder like they say. Link to comment Share on other sites More sharing options...
J.O. Posted June 16, 2009 Share Posted June 16, 2009 Can they be 100% sure that in the A300 vertical stab failure the stab was not breaking off before the full rudder deflection was recorded? I still have a hard time believing that the pilots were banging on the rudder like they say. The Flight Data Recorder showed exactly that. Full deflection in opposite directions in a fairly short duration. Link to comment Share on other sites More sharing options...
boestar Posted June 16, 2009 Share Posted June 16, 2009 As I said... I am just throwing it out there. Full Rudder deflection at high speed = BAD.....Period The fail safe mode of the limiter is FULL AUTHORITY. /END Link to comment Share on other sites More sharing options...
Pivot Posted June 16, 2009 Share Posted June 16, 2009 The Flight Data Recorder showed exactly that. Full deflection in opposite directions in a fairly short duration. Does the Flight Data Recorder show the exact position of the vertical fin while its recording the rudder deflections? Link to comment Share on other sites More sharing options...
Mitch Cronin Posted June 16, 2009 Share Posted June 16, 2009 I still have a hard time believing that the pilots were banging on the rudder like they say. If you think about getting hit by violent vortices that throw you into (among other things) a hefty yaw, you're liable to respond with full opposite rudder, don't you think?.... so almost in the same instant you do that, the vortex is gone, or is now knocking your bird differently, and the combined effect of that full rudder deflection (the rudder limiter was not yet in play IIRC) and momentum have created what you now see as a need for full rudder in the other direction.... I don't think it's hard to believe at all. I do, however, find it hard to believe that an aircraft that will not take that, without breaking up and falling out of the sky, is to be considered airworthy! Link to comment Share on other sites More sharing options...
Don Hudson Posted June 16, 2009 Share Posted June 16, 2009 Pivot; Does the Flight Data Recorder show the exact position of the vertical fin while its recording the rudder deflections? No, there would be no point to the parameter. However, the DFDR and where installed the QAR (for FDA programs) do record lateral 'g' loads. The sample rate is usually 4 x second. Providing the location of the 'g' sensing equipment is known, (usually the IRSs but not excusively), the appropriate engineering math can be applied and the lateral 'g' loading on the vertical stab can be determined. It was a lateral 'g' loading of approximately 0.35g that broke the fin on AA587. If that seems small, I understand that the actual force that broke the fin was 1.93 of design loading, (requirement is 1.5x). In other words, the failure was extraordinary. FYI regarding sensors, we know that the vertical 'g' sensors and vertical 'g' parameter on the B777 is unreliable due to the location of the sensors, (cockpit). There is a good discussion of this in a paper on the B777 loads analysis by UDRI, (University of Dayton, Ohio), (with whom we cooperated in an analysis of the CRJ a number of years ago). J.O.'s completely correct btw - there are some revisionist historians in the current discussion on AF447 seeking to say that CFRP delamination was the reason the fin broke off AA587. The AT incident perhaps bolstered their case but there was no evidence of this when the lugs/attach points were examined. There was evidence of hydraulic fluid incursion in the AT rudder, I understand. Link to comment Share on other sites More sharing options...
Homerun Posted June 16, 2009 Author Share Posted June 16, 2009 Mitch, no transport aircraft is designed to take full rudder application in one direction followed by full deflection in the other direction. The load is immense. Link to comment Share on other sites More sharing options...
Mitch Cronin Posted June 16, 2009 Share Posted June 16, 2009 Mitch, no transport aircraft is designed to take full rudder application in one direction followed by full deflection in the other direction. The load is immense. So I understand.... That was a surprise to me to learn that. To my mind, they either A; should be. ...or B; should be designed so as to prevent any such loads from EVER being applied. What other single input is available that if reversed too quickly would cause total hull loss? None, I hope! .... Link to comment Share on other sites More sharing options...
handyman Posted June 16, 2009 Share Posted June 16, 2009 What other single input is available that if reversed too quickly would cause total hull loss? None, I hope! .... Friendship with your local grease monkey! Just kidding. I hope so too but rudder application in flight amounts to "taking care of your machine". It's kind of like red-lining your car or driving down the road at speed and rapidly turning the wheel. Bad things may happen if you don't respect the equipment. Good pilots use finesse and are smooth on the controls. Weak pilots create their own turbulence! Link to comment Share on other sites More sharing options...
BoomerPete Posted June 16, 2009 Share Posted June 16, 2009 As I said... I am just throwing it out there. Full Rudder deflection at high speed = BAD.....Period The fail safe mode of the limiter is FULL AUTHORITY. /END Boestar, This is incorrect. On the A330 a failure of the rudder travel limiter results in deflection being limited to the maximum value calculated for the conditions existing immediately prior to the failure. In this case that would be about 6 degrees versus the full authority which is on the order of 30 degrees. The full range capability for rudder deflection is only restored when slats are extended. Pete Link to comment Share on other sites More sharing options...
DEFCON Posted June 17, 2009 Share Posted June 17, 2009 That would seem to be a well conceived system. Link to comment Share on other sites More sharing options...
boestar Posted June 17, 2009 Share Posted June 17, 2009 Boestar, This is incorrect. On the A330 a failure of the rudder travel limiter results in deflection being limited to the maximum value calculated for the conditions existing immediately prior to the failure. In this case that would be about 6 degrees versus the full authority which is on the order of 30 degrees. The full range capability for rudder deflection is only restored when slats are extended. Pete I stand corrected then. I am not 100% up to speed on the airbus system but in many aircraft The failsafe mode is full authority. Leave it to airbus to confuse things.... Link to comment Share on other sites More sharing options...
Guest rattler Posted June 17, 2009 Share Posted June 17, 2009 More debris pictures including a large part of a galley. http://s635.photobucket.com/albums/uu79/DorianBanks/?start=0 Link to comment Share on other sites More sharing options...
Guest rattler Posted June 17, 2009 Share Posted June 17, 2009 The Associated Press, Wednesday, Jun. 17, 2009 02:43PM EDT .Experts say autopsies on victims of the Air France disaster suggest the plane broke up in the air. A spokesman for Brazilian medical examiners says they had multiple fractures of legs, hips and arms. A forensic expert who once worked at the U.S. National Transportation Safety Board says those injuries could mean the plane broke apart in air. Frank Ciacco says large chunks of the plane recovered are another clue. Mr. Ciacco says bodies and debris would be severely fragmented if the jet crashed intact. Earlier, French investigators said more than 400 pieces of the Airbus jet had been recovered from the Atlantic Ocean, where it crashed during a flight from Rio de Janeiro to Paris on May 31. There were 228 people on board Flight 447, including one Canadian. Link to comment Share on other sites More sharing options...
Guest woxof Posted June 18, 2009 Share Posted June 18, 2009 There was evidence of hydraulic fluid incursion in the AT rudder, I understand. To clarify about the AT event....... "results show the presence of hydraulic fluid contamination on exterior surfaces, but no indication of seepage into the structure." 3.1 Findings as to Causes and Contributing Factors 1. The aircraft took off from Varadero with a pre-existing disbond or an in-plane core fracture damage to the rudder, caused by either a discrete event, but not a blunt impact, or a weak bond at the z-section of the left side panel. This damage deteriorated in flight, ultimately resulting in the loss of the rudder. 2. The manufacturer's recommended inspection program for the aircraft was not adequate to detect all rudder defects; the damage may have been present for many flights before the occurrence flight. 3. This model of rudder does not include any design features in the sandwich panels to mechanically arrest the growth of disbond damage or in-plane core failure before the damaged area reaches critical size (such a feature was not specifically demanded for certification). http://www.tsb.gc.ca/eng/rapports-reports/...47/a05f0047.asp Link to comment Share on other sites More sharing options...
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