bushpilot Posted June 18, 2009 Posted June 18, 2009 I have no idea of the authenticity of this report or the observations in it, but the whole issues is worrying nonetheless: Air France Accident: Smoking Gun Found A Brazilian Naval unit reportedly found the complete vertical fin/rudder assembly of the doomed aircraft floating some 30 miles from the main debris field. The search for the flight recorders goes on, but given the failure history of the vertical fins on A300-series aircraft, an analysis of its structure at the point of failure will likely yield the primary cause factor in the breakup of the aircraft, with the flight recorder data (if found) providing only secondary contributing phenomena. The fin-failure-leading-to-breakup sequence is strongly suggested in the attached (below) narrative report by George Larson, Editor emeritus of Smithsonian Air & Space Magazine. It's regrettable that these aircraft are permitted to continue in routine flight operations with this known structural defect. It appears that safety finishes last within Airbus Industries, behind national pride and economics. Hopefully, this accident will force the issue to be addressed, requiring at a minimum restricted operations of selected platforms, and grounding of some high-time aircraft until a re-engineered (strengthened) vertical fin/rudder attachment structure can be incorporated. Les --------------------------(George Larson's Report)--------------------- This is an account of a discussion I had recently with a maintenance Professional who salvages airliner airframes for a living. He has been at it for A while, dba BMI Salvage at Opa Locka Airport in Florida. In the process of stripping Parts, he sees things few others are able to see. His observations confirm prior Assessments of Airbus structural deficiencies within our flight test and aero Structures communities by those who have seen the closely held reports of A3XX-series Vertical fin failures. His observations: "I have scrapped just about every type of transport aircraft from A-310, A-320, B-747, 727, 737, 707, DC-3, 4, 6, 7, 8, 9, 10, MD-80, L-188, L1011 and various Martin, Convair and KC-97 aircraft. Over a hundred of them. Airbus products are the flimsiest and most poorly designed as far as airframe structure is concerned by an almost obsession to utilize Composite materials. I have one A310 vertical fin on the premises from a demonstration I just performed. It was pathetic to see the composite structure shatter as it Did, something a Boeing product will not do.The vertical fin along with the composite hinges on rudder and elevators Is the worst example of structural use of composites I have ever seen and I am Not surprised by the current pictures of rescue crews recovering the Complete Vertical fin and rudder assembly at some distance from the crash site. The Airbus line has a history of both multiple rudder losses and a vertical Fin and rudder separation from the airframe as was the case in New York with American Airlines. As an old non-radar equipped DC4 pilot who flew through many a thunderstorm In Africa along the equator, I am quite familiar with their ferocity. It is not Difficult to understand how such a storm might have stressed an aircraft Structure to failure at its weakest point, and especially so in the presence of Instrumentation problems. I replied with this: "I'm watching very carefully the orchestration of the inquiry by French officials and Airbus. I think I can smell a concerted effort to steer discussion away from structural issues and onto sensors, etc. Now Air France, at the behest of their pilots' union, is replacing all the air data sensors on the Airbus fleet, which creates a distraction and shifts the media's focus away from the real problem. It's difficult to delve into the structural issue without wading into the Boeing vs. Airbus swamp, where any observation is instantly tainted by its Origin. Americans noting any Airbus structural issues (A380 early failure Of wing in static test; loss of vertical surfaces in Canadian fleet prior to American Airlines A300, e.g.) will be attacked by the other side as partisan, biased, etc. " His follow-up: One gets a really unique insight into structural issues when one has first-hand experience in the dismantling process. I am an A&P (Engineer), FEJ and an ATP(Pilot) with 7000 flight hours and I was absolutely stunned, flabbergasted when I realized that the majority of internal airframe structural supports on the A 310 which appear to be aluminum are actually rolled composite material with aluminum rod ends. They shattered. Three years ago we had a storm come through, with gusts up to 60-70 kts., catching several A320s tied down on the line, out in the open. The A320 elevators and rudder hinges whose actuators had been removed shattered and the rudder and elevators came off. Upon closer inspection I realized that not only were the rear spars composite but so were the hinges. While Boeing also uses composite material in its airfoil structures, the actual attach fittings for the elevators, rudder, vertical and horizontal stabilizers are all of machined aluminum."
Guest basscheffers Posted June 18, 2009 Posted June 18, 2009 To put things into perspective, this expert on the "flimsy" A300 is talking about the same no good plane that landed safely after it was hit by a surface to air missile with no hydraulics and part of the wing missing! When the report came out about the American Airlines New York crash, Boeing also released a document reminding Airlines to not do to the rudder what this crew did to the Airbus as it will make you exceed ultimate load on any of their airliners also. Almost 1500 planes with this design in service for close to 40 years. One confirmed case of tail failure blamed by the NTSB (not by French pride) on pilot abuse and agreed by arch-rival Boeing their planes wouldn't handle it either. Now a second crash where there is still no way to tell if the plane crashed because the tail snapped or the tail snapped because the plane was already out of control. Bit early to be jumping to conclusions. They have en exemplary safety record - I'd fly one any day. (and have many times)
poteroo Posted June 19, 2009 Posted June 19, 2009 Pilot Technique? I remember reading about several US crashes involving B737 types where the NTSB placed some blame on pilots using aggressive rudder in turbulence. This causes side forces sufficient to shear the fin attachments. So, if you're an ex aggie, taildragger, or glider pilot who's in the habit of banging those pedals - layoff it next time you hire an Airbus! happy days,
Guest pelorus32 Posted June 19, 2009 Posted June 19, 2009 This is an interesting subject. The NTSB report into the AA accident is here: http://www.ntsb.gov/publictn/2004/AAR0404.pdf Of particular interest are sections 1.18.4.1.1 and 1.18.4.1.2. Whilst they talk about "large reversals" the analysis prepared for this report showed that a single reversal of 6.5 degrees deflection was enough to exceed the design limit load of a transport category aircraft at Va. If you think 6.5 degrees is a great deal you should measure it on the rudder of your aircraft one day. You'll be more cautions next time you fly. This is a very important issue for us. RAAus style aircraft are not built to the same strength as a transport category aircraft but they are vulnerable to rudder reversals in just the same way. It's really worth reading that report. And also for the Airbus doubters noting that Boeing also issued warnings on this same subject. Regards Mike PS: I'm NOT speculating on the cause of the Air France A330 in this post.
Barefootpilot Posted June 19, 2009 Posted June 19, 2009 I know I always go to the guy who demolishes aircraft for my information on accidents.....
Guest ozzie Posted June 19, 2009 Posted June 19, 2009 I'd go for the engineers knowledge rather than the salesman or pilots pitch anyday.
Barefootpilot Posted June 19, 2009 Posted June 19, 2009 Thats true ozzie but he is titled "Maintenance Professional" not engineer! Its like an AME - they are not licenced and as soon as soon as anyone picks up a tool in a hangar they are an Aircraft Mantenence Engineers!
Ultralights Posted June 19, 2009 Posted June 19, 2009 why is there so much use of the rudder when flying heavy stuff these days? even flying the Jabiru, a aircraft that needs rudder quite a bit, i still only use the rudder to balance turns, thats about it, in turbulence, letting the aircrafts natural stability will do a very good job, no need to overuse any flight control. in the bumps, relax the controls, and only use the stick to correct large upsets from desired flight path, your ride will be smoother, and the aircraft less stressed.. the same goes for heavy jets i am told. it seams the newer crops of pilots love fighting the stick and rudder in the bumps. i dont recall many incidences of rudders and tailplanes failing on the older stuff, DC10's L1011, 747s etc.
Guest Crezzi Posted June 19, 2009 Posted June 19, 2009 In the case of the AA accident mentioned earlier, the plane hit wake turbulence Cheers John
facthunter Posted June 19, 2009 Posted June 19, 2009 Use of rudder. I wouldn't take it as said that pilots these days use a lot of rudder in the air. There emerges, from time to time, some"whacky" ideas in the minds of a few individuals, regarding so called beaut techniques for getting aeroplanes to do things better, but these are advised against and are not part of normal (or abnormal ) handling technique.. Yaw dampers make rudders do their job by damping ,as the name implies, yaw oscillations before they are really noticed. This would reduce fin load, not add to it. Lots of rudder is used with engine failures at or just above V1, but the load is moderated because the speed is relatively low. As the speed increases less rudder angle is needed as the rudder becomes more effective. The load stays much the same. Ie. enough to balance out the engine thrust assymetry. The rudder still retains it's prime function as a balance control, as it is with smaller planes as well. The exception being the intentional sideslip, but this should not be done at high speeds, so should not present a problem in that respect. The fact that the Airbus rudder is detached is a significant fact, but not proof of a deficiency as the circumstances that caused it to come off may be way outside the predicted ( and designed for) circumstances. Nev
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