More Structural Issues in the 447 Crash

In response to the loss of Air France 447, a French pilots’ union today asked its pilots not to fly the Airbus 330–the design of the crashed plane. Much has been made of the possible pitout tube failure on Air France 447. These tubes are sensors on the wings which might be prone to freezing up and distorting air speed, which in turn might mean the pilots were flying at too slow or too fast a speed to get through the thunder storms in the region.

There is a different theory having to do with the plane’s possible structural flaws, which brings us back to the question of composite aircraft materials, which I wrote about last week. Parts of the tail, recovered Monday, appear intact; the tail looks like it was ripped off the plane at the points of attachment. You can get some idea of what it looks like from this France 24 video.

To some observers, this bears a striking resemblance to the loss of the tail in the devastating American Airlines 587 crash in New York in November 2001. That plane was an Airbus 300. In an interesting comment on the Whatsupwiththat blog, a reader, Adoucette, writes:

The disturbing thing to me is that the A330 design is derived from the A300. Both have composite tails. In the AA-587 crash in Nov of 2001, the NTSB blamed the failure of the A300’s composite tail on the co-pilot. The NTSB claimed that the pilot made dramatic rudder inputs to counter wake turbulence from a 747 which had departed Kennedy two minutes earlier….
The NTSB said that the pilot, to combat mild turbulence, over controlled the aircraft by swinging the rudder fully to one side and then all the way to the other side, and it was this over-control which exceeded the tail’s design limits….

Now if this is possible from rudder inputs in mild turbulence in clear air at relatively low airspeed over NY, consider what could happen at high speed in major turbulence over the ITCZ [Intertropical Convergence Zone, a storm-prone area where trade winds converge].

Also making its way around the web is a report from NASA’s Langley Research Center on the possible effects of lightening on composite aircraft:

Traditional aircraft act as Faraday cages when struck by lightning, which means that the charge stays on the exterior of the aircraft.  However, as more aircraft are built using composite materials, we will need to understand the direct and indirect effects of lightning on those aircraft.  The researchers at LaRC are studying the  hazards of lightning on composite aircraft.  Some of the issues include the fact that magnetic flux can penetrate avionics wiring, and that lightning damage is often more severe than tests would predict (see this presentation for the full discussion).  Magnetic flux can penetrate composite aircraft more easily than metallic aircraft, inducing voltage and current on avionics wiring.

4 responses to “More Structural Issues in the 447 Crash

  1. The A330 HAS an aluminum fuselage, so the faraday cage (or lack thereof) comment doesn’t really fit here.
    Also, the design of the A300 rudder system and A330 rudder system – and the rudder limiting at higher speeds are completely different. (they were both hydraulically actuated rudders is about all they have in common.)
    If you’re looking for a rudder design flaw conspiracy, check out the Boeing 737 and it’s series of rudder hard-over accidents.

  2. This is an account of a discussion originally posted by George Larson, Editor emeritus of
    Smithsonian Air & Space Magazine:

    “I had a discussion 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 NY with AA.

    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 AA 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, FEJ and an ATP 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.”

  3. Can’t find it now, but saw a video of a rescue of helicopter passengers and crew in the north sea. The crash was attributed to lightning striking and blowing a piece of the tail rotor away. Commentary suggested that the carbon fiber transmits electric charge, heats up and delaminates. Also commentary suggested that composite materials haven’t been fully tested for this form of failure by proper authorities.

  4. Nick Morgan

    Thank you for this article which I found to be very informative.
    I have worked in the aircraft industry and will always have a great respect for all things that fly.
    Lets hope this issue will be resolved soon.

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