Assessing 787 in-flight fire

There are plenty of news stories accessible through Google, so we won’t recap the incident here.

Here’s what we can add to the story at this time (06:30 AM PST, Nov. 10); we’ll update as needed.

  • We’ve been told by a person familiar with the details of the incident that the fire in the aft electronic bay cause a lot of damage to the surrounding composite structure. The bay is located next to the wing box.
  • Flightblogger and The Seattle Times reported that the flight instruments failed and the Ram Air Turbine deployed; in a statement released by Boeing about midnight Seattle time Tuesday, Boeing denied that the instruments failed but did not address whether the RAT deployed.
  • Our source told us early Tuesday evening that there was a “cascading” series of electronic failures that redundancies failed to prevent. This is not necessarily inconsistent with Boeing’s midnight statement. These cascading failures, we were told, caused Boeing to ground the rest of the test fleet until Boeing has an understanding of the event. An hour and a half later, Flightblogger reported the test fleet had been grounded; Boeing has yet to confirm this.
  • In our role as aviation consultant to KIRO TV (CBS, Seattle), we predicted Tuesday during the early evening newscasts that the incident will be serious enough to cause a delay in the flight test program and most likely a new delay in first delivery, because the investigation into the cause of the first–even if it identifies the cause fairly quickly–may take long enough to effect a fix to induce new delays.
  • Dominic Gates in The Seattle Times, citing an unidentified source, said one possible cause could be an overheated electronics box that would be identified and replaced quickly. This may or may not be correct, but even if is, this may not be the end of it. Cooling the electronic bays was an early and persistent problem because of the heat generated by the all-electric airplane and cooling the bays was one of those vexing problems during the development of the airplane. If cooling proves to be insufficient and a contributor to the cause of the fire, who knows what redesign might be required. It is important to emphasis here that the unidentified source in Gates’ story is speculating and so are we.

35 Comments on “Assessing 787 in-flight fire

  1. Interestingly, someone precisely addressed this scenario almost a year ago:

    http://blogs.crikey.com.au/planetalking/2009/12/15/testing-times-begin-for-the-787-dreams/

    “Making a composite airplane that generates around 1 thousand KVA electricity (approximately 1 megawatt) means that you have a tremendous heat load running through the systems and wiring. Dissipating all of that heat, in confined spaces where all of these systems are stacked up on one another, is another huge challenge. Guess what? Composites don’t dissipate heat, they hold them in. So, you’ve got a flying insulator, generating mega heat, that you’ve got to get rid of. However, the environmental control systems are already overtaxed. So, what to do?”

    ” You’ve got a electronics cooling system that has never been tested in a commercial airplane application before. There are problems galore. I can’t go into detail- just trust me on this one.”

    “The systems architecture for this airplane is highly integrated. In plain English, that means it’s a bunch of dominoes. Trying to prevent cascading failures is a huge challenge.”

  2. Developing 1MW of power is not new, the various Boeing RC-135 models have been doing that since the 1960s. Although they use engine bleed air in the cooling and heating, they do use different A/C packs to help with cooling. The RC-135E, Rivet Amber (that crashed, possibly due to structual failure of the tail section) also had a heat exchanger pod under the right wing (the left wing had an additional pod mounted generator). Boeing does not need something like that, but a reengineered heat exchanger for each of the two electonics equipment bays, with improved air circulation fans, might solve the problem.

      • Not sure about the RC-135, but AWACS uses liquid cooling for the systems which power the surveillance radar antenna.

    • of course all cooling solutions so far have been implemented in ac with heat exchange literally build into the skins (much less so for composites – they loose strength much more rapidly when temperature increases), and had engines build to provide large amounts of pressurized cool air.
      All this is simply meant to illustrate the challenge Boeing set their engineers. It’ll be mighty interesting to find out how they finally fix this. A big radiator in the belly fairing will heat the fuel, anything requiring airflow will reduce aero performance… Maybe replace a piece of the skin somewhere with a big slab of copper, with sintered heat pipes ala computer cooling.

  3. Scott, Why did you conclude on Tuesday evening without factual and clarifying information that this incident would be the cause of a further delay.

    Had your sources indicated the nature of the incident at cause or did you think that ANY incident like this would create a sufficient investigation so as to impact testing?

    Is there any possiblity that this is much less of a problem than being described? Why is there not the possibility of an externally caused issue that can be located and repaired easily.

    There just seems to be a belief that Boeing can get nothing wrong and the testing should go smoothly and without incidents.

    Please clarify…thanks

    • That none of the other flight test planes are flying might indicate that Scott was correct on the first point. Most people in aerospace came to the same conclusion independent of Scott’s evaluation.
      Re: the seriousness of this incident being overplayed. Electronics fires on aircraft are always a serious issue. Full stop. Period.
      This aircraft was lucky in that they were already on approach to the airport. Try and imagine how much more serious the issue might have been if they were an hour out from the nearest place to land.

  4. Curious, I’m not sure what you’re tying to imply. A fire that substantially knocks out the plane’s control system and which spreads smoke into the cabin is by any definition a serious incident. Luckily the circumstances meant the crew and passengers managed to get down safely. At the very least the incident indicates the importance of thoroughly testing of each new plane and that testing is not routine: the crews run a real risk.

    I would expect Boeing and the authorities to reassess the design of the electrical control, cooling and fire containment systems in the light of the incident. This will necessarily take time.

    • Curious, FF hits the nail on the head. With a fire such as described, plus information we received from a person with knowledge of the incident and the damage, investigation by the Feds could take some time. This time, alone, could induce a new delay. Notice the use of the word “could.”

      Also recall that fire and composites have drawn a good deal of comment in the official FAA record. Analysis of this fire damage could (there’s that word again) further add to the investigation time.

      As noted in another post, Robert Stallard of RBC has suggested a new delay as a result of this incident. We haven’t seen notes from other analysts yet but will not be surprised if there is a chorus suggesting such.

      • The FAA will not be using this event to understand how composites behave in a fire. Whatever occurred onboard ZA002, it certainly wasn’t planned for or monitored, meaning it was not a controlled test. As such, there will be certain details about it that cannot be known (e.g. precisely how hot it was, how long it lasted, etc.) Without knowing these details, it is virtually impossible to draw any meaningful conclusions about material properties and behaviors in a fire. Besides, 787 certification conditions related to fire and composite structure were long ago completed. The FAA’s interest in this event will be purely 1. how the fire started 2. what systems were affected 3. how other airplane systems responded to any failures.

        Oh, and Scott, regarding your original post, the aft equipment bay is surrounded on all 6 sides by composite structure. The wing box is only on one of those sides.

    • Where did we get confirmation there was “a fire that substantially knocks out the plane’s control system”?

      • The pilot looks to have been in control of the airplane at all times. The fire is reported to have caused major damage (Jon Ostrower, Dominic Gates and others) to the rear electronics bay where it was localized. It presumably could have destroyed the entire the entire bay and rendered the plane uncontrollable.

        My words weren’t clear. Sorry.

  5. FF I am not trying to imply anything but what the facts are. Boeing disclaims, contrary to reports, that the pilots did not lose primary flight display”

    We do not know the source of the smoke..whether there was a fire, etc. So I was asking without this information, how a conclusion could be made. What if the smoke was caused by a piece of testing equiptment?

    Your statement alone,” a fire that substantially knocks out the control system” is an example of uninformed, speculative and premature information. If you were there it would be helpful to have you identify the basis on which you draw your ostensibly knowledgeable conclusion.

    I prefer facts and confirmed information. The rest is incindiary

  6. Scott,

    I read more speculation coming from people who claim they are familiar with the sitution. I too am “familiar with the situation “…it is a question as to what this familiarity is.

    If this person was so familiar, then additiona details should be described, etc. Otherwise, it is unsubstantiated and possibly misleading.

    All I am asking for are factual details so others can draw appropriate conclusions. I hope some time will make my point clearer……such as whether systems really went down or not …whether voluntarily or automaticlly, etc.

    Trained as a Lawyer, my mind prefers fact to speculation and disinformation

    • Curious, where to get the factual these days? Official statements proved worthless and unconfirmed “rumors” correct. Times ave changed, waiting for factual details makes you run 2-6 month behind. Critical skilled eyes filtering the massive unconfirmed info streams is what’s driving the stock values.

    • If you were trained as a lawyer I would say you were trained to create facts that help your position, not help the overall picture.

  7. If it wasn’t for testing, the 787 would have been right on time.

    so would the 380

    • because the one they pushed outside on 7/8/7 could have taken to the air on day one?
      Because the wiring on the 380 did fit, all the reports to the contrary and the massive re-engineering effort of the systems diagram was a hoax?

    • The first A380 prototype took ~10 month from doing the initial “LEGO” thing
      to first flight.
      The following testflights and certification programme were rather uneventfull
      at that.
      Dreamliner industrialisation problems are just now starting to surface.
      ( in this context: I just can’t see how one could write “analyst” and
      “70..90 Dreamliner deliveries expected in first year after EIS”
      in one sentence.
      Or is “Wallstreet” the qualifyer here?
      They must have a direct access tunnel to LaLa Land there )

      • I’ll be impressed if they get 7 to 9 out in the first year.
        Haven’t heard anything about the cabins yet. That hurt Airbus on the A380. I wonder if Boeing has a better grip on customizing.

  8. wait what lawyer and facts? this does not compute 😛
    besides flames was confirmed to be seen by people onboard in the rear electrical/electronics bay

    whats interesting here is that they experienced a cascade of failure in addition to the fire. Which would mean that Boeing has 2 problems to solve. 1) why did a fire start 2) why did the redundencies fail to kick in
    my rule of thumb is whenever you hear of a failure cascade its a baaaad thing xD

    I agree that this will most likely lead to more delays as Boeing was exactly running the currrent schedule on a comfortable buffer. How long will depend on the seriousness of the issue. But as said by Hamilton the investigation alone will practically ensure some sort of delay. I am also sure that ZA002 will be unavailable for testing for some time due to investigation/repairs which isnt exactly helpful for their schedule either.

    No matter how this goes I cant see this not affecting the schedule negatively.

  9. Breaking Information. I refer you to Jon Ostrower’s twitter reference to the Dec 29,2009 piece “Better to Know a Dreamliner:ZA002.

    It indicates that part of the testing assigned to the Test Plane #2 was “to look at the aircraft’s electrical system to determine its MAXIMUM LOAD by connecting resistors which act as heaters. These heaters will pull electrical power from the engines and generation systems…( read more directly).

    This information is very interesting if it accounts for what was a cause of this incident.

    Jon, like Scott Hamilton, is a serious journalist and this reference may have some important bearing on the nature of this incident. It may well show the risks, consequences , responsibilities and rewards of testing.

    There is more to this story and it will eventually lead to a better understanding as well as safety.

    • Curious,
      I have mentioned this elsewhere but I will repeat it here. With 30 people on board, they were not doing any sort of testing. Or at least they should not have been. This, as the press has reported, was a flight to Texas, where they were then going to perform tests on the hydrogen generation system. These people were being ferried along with the plane to provide ground support for those tests. Flight tests are not carried out with an excess number of people on board the aircraft. Even the most innocent sort of testing can turn dangerous quite quickly. Hence it would be highly unlikely they were performing maximum load tests during this flight. If they were, I believe there troubles are then just starting.

  10. The temperatures at altitude are subfreezing and the air is rushing past at hundreds of mph. How difficult is it to take some of that ice cold air and cool the electronics with it?

  11. CM :The wing box is only on one of those sides.

    No, the aft E/E-bay and the wing box are on opposite sides of the main landing gear wheel well.

    • You are correct. The aft wheel well bulkhead forms the forward “wall” of the aft equipment bay. The wing box is not adjacent to the aft E/E bay and this event at all.

  12. Aero Ninja :
    I’ll be impressed if they get 7 to 9 out in the first year.
    Haven’t heard anything about the cabins yet. That hurt Airbus on the A380. I wonder if Boeing has a better grip on customizing.

    The Dreamliner was to be “lean options” and the Koito seating bruhaha should
    have calmed down quite a bit.
    IMHO the unfathomable part is how long applying change backports to “finished”
    frames will take ( and at which blockpoint in production these will have morphed into manufacturing changes. If I got the gist of published information, fixing the
    lawn ornaments could take more than a year.
    The existing line is said to have a hard limit of 7 frames ( versus 10 planned resp. 120/a) per month resp. 87/a at full tilt. My not so honest guess on deliveries is:
    1 in 2011 ( just to be able to say “EIS as planned” and just short of some shareholder waypoint )
    35 in 2012 ( 15 regular plus most of the lawn ornaments )
    30 in 2013 ( regular line only )
    45 in 2014 ( regular, no idea when the second line will be ready.

  13. folks, i dont want to b a smart ass, but boeing & its engieers spend billions on this plane and do not worry about cmposites retaining heat plus how to cool computetrs. this is basic stuff. what goes ?

  14. I can’t quite connect a suspected overheat of electronics to fire.

    Rather, overheat can cause component failures which lead to systems failures and I suppose if things are not designed properly can then fail over in a manner that could cause something to cook.

    I would think that component, module, and overall system design is such that an overheat would cause a shutdown, not a meltdown.

    Could it be that the fire has another cause – and the systems failures which led to RAT deployment (massive hydraulic/electrical failure assumed) was a result?

    And isn’t the test programme such that the aircraft is loaded with electronics specific to flight test? Perhaps we may learn that the cause is rooted in the test gear, not the default aircraft systems. It just so happens that the aircraft did not respond well to burning up 🙂

  15. Earlier reports stated the wiring had to be changed on the first three test aircraft – to save weight. Then it was announced the first three a/c weren’t commercially viable. Now is the time for the insurance company to step in and pay for the “extensive fire damage”. One down – two to go!

    Jim Helms

  16. January 2020, Breaking News. The 787 Dreamliner has been certified by the authorities. The remaining 3 airlines flying will take at least 2 each. They will draw straws to see who will fly the plane first through convective activity. The Briggs & Stratton engines have been performing perfectly.

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