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Failed Avionics a Possible Cause of BA038 Crash

Posted by Soulskill on from the we-will-be-landing-shortly dept.

Muhammar writes "As you may have heard by now, both engines of the Boeing 777 aircraft flight BA038 suddenly cut off without warning at very low altitude and low speed during autopilot-assisted landing at Heathrow. A prompt reaction of the pilots prevented the stall and saved all lives aboard. The crash landing short of the runway tore off the landing gear on impact, and the fuselage plowed a long, deep gouge in the grass. With the investigation ongoing, the available information points to an electronic control problem as the most likely cause of the sudden engine power loss."

11 of 369 comments (clear)

  1. Errrrr.. by Deekin_Scalesinger · · Score: 5, Insightful

    A bit of FUD here I think - unless I read TFA wrong, the entire thing is under investigation and no one is saying anything for at least a month. The autopilot apparently sensed the need for more thrust and warned the pilots of this. It might be premature to say that a software problem is the likely cause of failure...

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  2. BA are extremely happy about the crash by Malevolent+Tester · · Score: 5, Funny

    They actually have a decent excuse for lost luggage for once.

    --
    If you haven't made a developer cry, you've wasted a day.
  3. No, not the Avionics... by bradgoodman · · Score: 5, Insightful
    No - I don't think so. The autothrusters responded properly, but they literally just move the throttle levers, to which the engines didn't respond.

    The pilots then manually increased throttle - to no avail.

    For both engines to malfunction like this at the same time greatly seems to point to a fuel delivery problem.

    This does not necessarily mean "running out of gas" - as a plane like this has multiple tanks, valves and pumps, all of which can be configured multiple different ways - which change during the flight.

    A simplistic example: they could have been running both engines off one tank - which went dry - though another was full - or both engines were being fed from a common fuel pump which failed, etc. These things *shouldn't* happen - but the investigation will tell...

    1. Re:No, not the Avionics... by timthorn · · Score: 5, Insightful

      No, this happened at the worst possible point. Over the middle of the ocean the aircraft will have been at perhaps 38000 feet and in a flight configuration, giving time to attempt various restart procedures, declare an emergency and glide to an airfield - a transatlantic flight is rarely out of gliding distance to a landing strip, and a flight from China likewise.

  4. Possible autothrottle problem by bananaendian · · Score: 5, Interesting

    With the investigation ongoing, the available information points to an electronic control problem as the most likely cause of the sudden engine power loss."

    What I've read is that the pilots observed a relatively gradual loss of power symmetrically on both engines. This tells me that I can rule out engine problems with FADEC and fuel. It all points to the auto-throttle. Autopilot tells where it wants the plane to go and autothrottle calculates how much throttle is needed. It then commands both engines FADECs via the bus system which is doubly redundant. What I'm thinking is that auto-throttle is supposed to be backed up, bypassed by a manual direct control to the engine FADECs from the cockpit throttle control?

    Any B777 avionics mechanics around - I only know military jets...

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    1. Re:Possible autothrottle problem by BlueStrat · · Score: 5, Insightful

      Not a commercial aircraft airframe and powerplant mechanic, but I was a senior avionics technician for many years dealing with corporate and private jets.

      What I've read is that the pilots observed a relatively gradual loss of power symmetrically on both engines.

      Interesting. Do you have a link to the source for that? Not that I doubt you, just curious to parse it myself.

      This tells me that I can rule out engine problems with FADEC and fuel.

      FADEC, possibly, but fuel? It's quite possible there was either water or crud in the fuel, especially since the aircraft almost certainly took on fuel in China, and China seems to have had problems of late with products being adulterated in some form. The crud could cause blockages in the filters from the tank(s). The water would cause an increasingly-diluted fuel mixture to enter the engines as the level dropped which might also cause the gradual loss of power.

      The two most-likely culprits I would examine first are the discrete devices at either end of the control path that send the data and receive it at the other end, and the cables and connectors used to transmit the data.

      The next point I'd check would be the power supply that powers the electrical actuators that physically move the actual throttles in each engine. This supply would be separate from the power used for the electronics, as it would be a relatively high-current source. This might also be caused by cabling/connector problems.

      Aircraft tend to have many problems with cabling due to high vibration and multiple pinch-points and stress and vibration/abrasion at support points, as well as contact problems at connectors.

      Another very major problem is human error. In many cases the turn-to-lock type connectors are in very tight spaces, sometimes so much so that it may only be visible by a small mirror and flashlight held by the tech while he may be laying on his back or nearly standing on his head. I had a whole set of strange-looking pliers of different lengths and weird angles with curved padded jaws for just this purpose in my tool box, along with small hand-held extend-able flexible-tubing-mounted inspection mirrors and flashlights with the head on flexible tubing as well.

      It can be very hard to tell, given the above circumstances, if the locking sleeve on these aircraft instrumentation connectors had been twisted far enough to complete the lock. It doesn't take much imagination to see what could happen given time, vibration, and G-forces.

      Of course, these are just my rough guesses, and I don't have enough information to really make any informed statements.

      Cheers!

      Strat

      --
      Progressivism (aka US 'Liberalism'): Ideas so good they need a police/surveillance-state to enforce.
  5. Patience by Linker3000 · · Score: 5, Insightful

    Let's just wait for the official forensics rather than patched together rumours shall we?

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    AT&ROFLMAO
  6. Re:Are the pilots heros? by bradgoodman · · Score: 5, Insightful

    The word "hero" is thrown around a lot these days...

    I believe what they meant, was that the pilots realized that things were going wrong, and the "normal" reaction would be to add thrust. When they realized that they couldn't add thrust, that this would result in loosing airspeed, entering a stall, and crashing

    So they realized that an alternative was to lower their angle-of-attack, preventing the stall, and maintaining a bit of airspeed. This would have the unfortunate side affect of landing well-short of the runway (and perhaps airport) and destroying the aircraft - but given the information available - was a bad - but the best alternative

    So they implicitly decided the best course of action was to glide the airplane and ditch it in a field - not a decision that would have exactly won them any praise had they read the situation wrong - but it saved everyone

  7. Pointless speculation by we who know nothing by caseih · · Score: 5, Insightful
    A comment on airliners.net's forums is very appropriate for us slashdotters I think:

    A BA 772 landed short of the runway. Initially, speculation was entirely wild, ranging from random double engine failure to fuel contamination to one engine being actually working. Some witnesses said the plane came in high and fast, others said low and slow, others mixed the two together; all agree it was nose-high. A few helpful posters who actually knew something contributed. Some posters asked why the tires were brown...after the plane had skidded through a wet, grassy area on collapsed landing gear. A few posters got into pedantic discussions on various features of the 772 or its operational history as compared to the 340. Others took great pains to demonstrate to the world their lack of basic knowledge of unpowered flight. Few seemed familiar with the notion that fan blades windmill even when no power is applied to the engine. Most all were engaged in a game of nerdy one-upmanship in which they vigorously tried to validate their lofty views of themselves based on their aeronautical knowledge. In sum, we know about as much now as we did when the plane went down: the plane turned onto final, engines did not respond to power inputs, plane landed short of runway, slides deployed, people all survived, plane almost certainly a W/O. Shockingly, neither BA nor Boeing has decided to keep the 15-year-old speculation artists abreast of the situation.
  8. Re:Software? by Anonymous Coward · · Score: 5, Informative

    If a cell phone can do this much damage, why the hell am I allowed to bring one (several even) on a plane?! These days, a swiss army knife will maybe get you as far as row 6 before people dogpile you, and they are confiscated. But a plane has easily 50 cell phones on it at any given time. If the only thing between me and engine failure are passengers dutifully following crew member instructions, then we are all screwed. So I am going to respectfully suggest that you are mistaken, because the alternative seems ludicrous.

  9. Ah, no, they don't glide THAT well by VAG-Man · · Score: 5, Informative

    Trans-Atlantic flights are often 90 minutes of flying time from a suitable runway. Trans-Pacific flights can be 3 hours or more of flying time from a suitable runway. Needless to say, airlines cannot glide with no power for hours. Air Canada Flight 143 (see http://www.wadenelson.com/gimli.html) was estimated to have a glide ratio of 11:1 with both engines windmilling. So from 40,000 ft, the maximum glide distance would have been about 100km. Sink rate was estimated at 2000 ft/sec meaning with all engines out, you will be visiting some destination at sea level within about 20 minutes.