ZA001 proceeds toward final gauntlet ahead of 787 taxi testing

ZA001-May29-09.jpg

First flight remains targeted for December 15, depending on the weather.

Before ZA001 can complete its final round of taxi tests, Boeing will take the first 787 though
two to three days of final gauntlet tests for final check outs of the aircraft’s 92 systems.

Currently, the Final Gauntlet is scheduled to begin as early as Tuesday, December 8 and stretch through Wednesday or Thursday. The Final Gauntlet is a series of closed loop ground tests that will evaluate ZA001′s systems while fooling the aircraft in believing it is flying.

Sources say the Final Gauntlet will be split into two primary blocks. The first includes a B1 first flight profile, the standard checkout ofall aircraft systems as part of standard production testing. The second block will be a more rigorous “first flight” final gauntlet with an expanded profile of tests and failure scenarios.

Today (December 7) is being spent undergoing a flight test safety review, while tomorrow will include the setup of the aircraft Flight Emulation Test System (FETS), that interfaces directly with ZA001 and governs the gauntlet tests.

The FETS system is part of a Boeing-patented method (PDF) of activating and monitoring the aircraft during gauntlet testing. The 1993 patent abstract reads:

The system thus generates an initial set of stimuli similar to what anaircraft would be exposed to when in flight; monitors the response ofthe aircraft to the stimuli to which it is exposed; and, in responsegenerates an updated set of stimuli to the aircraft. The system alsorecords the response of the output responses of aircraft components sothat they could be monitored by personnel charged with insuring thatthe aircraft is functioning properly. The system can also be used totrain flight crews since it can be used to place the aircraft “in theloop” during a flight emulation.

We see the FETS system manifested today in the flight line bread truck that attaches directly to the aircraft systems to fool the inertial and air data systems, while applying simulated flight dynamics and aerodynamics that govern aircraft performance. This “stumuli” causes the aircraft systems to respond, allowing Boeing to see their in-flight performance while remaining on the ground.

Last Friday, ZA001 was spotted rolling near flight line stall 105 as the aircraft tested its brakes while operating solely on main battery power, say program sources. According to Aviation Week’s Guy Norris, Boeing also tested the latest flight control software as part of regression testing. The software is believed to be version 8.0.2, say sources familiar with the testing.

Once the Final Gauntlet tests wrap up by the end of this week, Boeing will head into taxi tests this weekend for the final round of low and high speed tests for final checkouts of the aircraft ability to slow down and stop safely.

Photo Credit Jim Larsen – Taken May 29, 2009

21 Responses to ZA001 proceeds toward final gauntlet ahead of 787 taxi testing

  1. alexandar December 7, 2009 at 7:44 pm #

    What about the static test results? Randy said it will take 10 days to analysis the results. Has Boeing announced a successful test? All they have said was that they completed the test.

  2. m in Seattle December 7, 2009 at 9:23 pm #

    OK…a really dumb question :-)
    With the “bread truck” simulating, as near to as possible, the profile of the first flight, do they have a “real” response from the grounded ZA001, in terms of engine thrust etc. If so, how do they prevent landing gear damage as the plane tries to surge forward. Ok …you can stop laughing…but I think about these things!!

  3. Engineer #3 December 8, 2009 at 12:35 am #

    They are not actually “flying” the plane on the ground. Just flying it in the computer. They may actuate control surfaces, but the engine will not be going more than necessary to run the systems.

  4. Don December 8, 2009 at 12:39 am #

    Would it be possible for you to direct me to documents outlining the various test flight profiles (i.e.: B1 first flight)?

    Thanks

  5. Shaggy December 8, 2009 at 2:10 am #

    Interesting that it will only take them 10 days to analyse the results of the static tests this time around whereas it took them almost a month to realise (immediately after the Paris Air Show) that they had a problem on their last test in May (or was it even April).

    I also find it funny that they haven’t gone to the same level this time around (120-130%) like they did back in the spring.

    In conclusion, they test to a lower level and are able to evaluate the results much better.

    Am In the only one here whi finds all of this very strange? I imagine all those people launching lawsuits at Boeing would find all this to be further evidence.

  6. Agnes December 8, 2009 at 2:36 am #

    I think they don’t need to re-check all the things that were right the first time, and only need to check the things that were fixed after the first test. In that case it makes sense that they don’t need as much time as for the first check.

  7. BennyJ December 8, 2009 at 2:48 am #

    I guess there was no need to redo exactly the same test as they did back in the spring. One of the results of the first test was that their model did not match the actual results but also that the wing sustained a load of 100% without any problems. They could have started flying at that time but due to the incorrect model, their testing would not have been very effective. Thus, they decided to install the fix before they start testing. With the latest test they probably only verified that their model is correct now. There was just no need to go beyond 100% again. They will do the ultimate load test later in the test program which is a normal thing to do. Why should they risk breaking the wing now when they still need it for testing and analysis? Wouldn’t make sense.

  8. Tim December 8, 2009 at 5:10 am #

    Shaggy, before the delay the work they were doing was to try to work out what went wrong and whether an interim fix would work. That’s an order of magnitude more work than checking that the test readings match predictions.

  9. Engineer #3 December 8, 2009 at 9:08 am #

    Uh hum, They took the static airframe to 150% of limit load.
    This is more, I repeat more, than they did previously.

    Limit load, for those who don’t know, is defined as the largest load the airplane will ever see in it’s life, or 2.5 times the force of gravity on it’s structure.

  10. Luke December 8, 2009 at 10:38 am #

    Um, no, they have not gone to ultimate load yet. That is (likely) the final test for the static airframe.

  11. NDT INSPECTOR December 8, 2009 at 11:31 am #

    Anybody get a chance to read this one? Comments? Thoughts?

    http://seattletimes.nwsource.com/html/businesstechnology/2010449191_boeing08.html

  12. Shaggy December 8, 2009 at 11:59 am #

    Boeing discovered their model was incorrect after the test that went to 120-130% of limit load. Why would 100% be sufficient now?

  13. Shaggy December 8, 2009 at 12:19 pm #

    Engineer #3

    Boeing stated they went to 100% of the load that the 787 wing would see in service. Assuming they meant the highest load that it would only ever encounter one time, then by definition, that is the limit load.
    By all means, please look it up.

    Ultimate load is 1.5 times the limit load (150%) of limit load.

    Boeing claims that the 787 wing has been up to somewhere between 120 and 130% of limit load. That is not quite ultimate load.

    They are apparently going to try ultimate load in the spring. Probably with another few incremental tests in between. Just to truly see if their model is now correct.

  14. wannabe engineer December 8, 2009 at 4:43 pm #

    Isn’t there such a thing as “certified for flight testing only” (not for passenger flight). Much the same as bringing damaged planes back for repair (flown back to the shop without paying passengers).
    Isn’t the 100% of load just that, safe enough for flight testing only?

  15. alloycowboy December 8, 2009 at 5:02 pm #

    Does anyone know if Boeing will retract the gear on the first flight or will they follow tradition and keep them down?

  16. Shaggy December 9, 2009 at 5:24 am #

    Hi Wannabe engineer,
    from what I know (like many others here, no expert on certification), the 100% (limit load) test is sufficient for the experimental aircraft certificate. Boeing plans on doing the ultimate load (150%) test in the spring. If that passes, then they have met the wing loading criteria for a type certification.

    I do not dispute that they do not need the ultimate load test for first flight. I am questioning what seems to be a change in policy on Boeing’s part as far as how far they are testing the wing now and how far they tested it back in the spring. That they did not discover their “modelling problems” until they were in the 120% -130% range back then, and deemed this to be sufficient grounds to postpone a first flight with a limited flight envelope is quite revealing. Yet now having tested to a lower level, they feel all is okay for a first flight with a (presumably) normal flight envelope.

    I also have an issue with these “freeze holes” delamination reported in the media. They quoted a document where an engineer noted that the holes were not acceptable for first flight as they are yet some Boeing spokesperson contradicted this document by stating that no repair was required for first flight.

    I maintain that they are still not being totally honest or forthright. That Boeing could behave like this still seems to be hard for some here to accept or even ponder. But based on the last 2 plus years (starting with the wonderful rollout of the empty shell held together with temporary fasteners which was supposed to fly about a month or 2 later, I am more inclined to suspect them of deceit rather than trust them.
    As Mr. Bush once mangled, “Fool me once, shame on you. Fool me twice, shame on me!”

  17. Dan December 9, 2009 at 8:31 am #

    747-8 N747EX has started its engines……no coverage on that anywhere yet????

  18. Luke December 9, 2009 at 9:12 am #

    The reason they would have found the problem at 120%-130% is that they likely exceeded a safety limit on the strain gages. When testing you set limits. Exceed it, you stop and figure out what is going on.

    They’re now watching those parameters closely in the data aquisition system. Test to the required Limit Load, if it matches the predicted behavior then one would conclude that, as long as nothing goes “pop” (which is a good assumption if all strains are matching predictions, considering that the allowables are all B-Basis), the model is now accurate. No need to test further at this time, get on with the test plans.

  19. John in CA December 9, 2009 at 10:10 am #

    There are different requirements for each test. On the first wing test they found that they were getting delamination before 100%.

    The 100% test needs the aircraft to be able to go to 100% without damage….

    The 150% test requires the airframe to make it to 150% without failure….which means that some damage to the wing to wing box could take place if you go over 100%…but it can’t fail until it hits 150%.

    So…in last weeks test they wanted to reach 100
    % with no damage….if they make that then they can fly the plane and do all the testing they need to do without limitations.

    At some point they are going to push the wing an wing box to breaking….until that point they want to do all the testing they can before they break it.

    It was also my understanding that when they did the wing test during the summer they actually went over 150% before it broke….quite a bit over….what they found later was that they got delamination sooner than expected….

  20. Aero Ninja December 9, 2009 at 4:18 pm #

    John in CA, you said, “It was also my understanding that when they did the wing test during the summer they actually went over 150% before it broke”.

    How do you come to that conclusion? Have you read it somewhere or did someone on the “inside” tell you that?

    I, and probably many others, am interested to know more about that statement.

    Cheers.

  21. John in CA December 10, 2009 at 8:45 am #

    @Aero…
    http://www.seattlepi.com/business/388382_air19.html

    Just one of many public links in regards to the wings.

    Do a search on “Boeing 787 wing test”…actually, the tests were done in 2008. It was the integrated test (wing + wing box) this last summer that revield the flaw in the wing box to wing.