Explanation and clarification on ZA002′s landing gear

As you may have noticed, ZA002 touched down at Boeing Field with its landing gears doors open instead of stowed as we saw on ZA001 last Tuesday. The reason for the open position at the time of landing had to do with the resolution Neville and Carriker used to fully straighten a component of the nose landing gear.
The Seattle Times has reported that “Part of the gear assembly “was tilted to the aft by 15 degrees.”
Specifically the part in question was the nose landing gear drag brace that, according to an airline pilot who holds type ratings on both the 757 and 767 and flies for a major US carrier, a drag brace “braces the airplane [landing gear] gear when a rearward load placed on the gear. This will help prevent gear collapse under higher than normal load situations.”

Boeing says the telemetry room, or TM, noticed a conflict in the readings on the nose landing gear and asked for a visual inspection by the T-33 chase plane. 

The chase plane reported that the nose landing gear drag brace was “not completely straight,” adding “there’s about a 15 degree angle to it.”

Neville cycled the landing gear doors and later the landing gear a few times to try and properly align the drag brace.

The crew ultimately selected the Alternate Gear extension option which unlocked the nose and main landing gear doors, dropping the landing gear into position, resolving the issue, and explains why we saw the doors open on arrival. Additionally, the use of the ALTN GEAR option ensured that any potentially unresolved issue with the nose gear would not be an issue on touchdown.

It’s quite common to see a 777 making an approach to KPAE after a production test flight with the landing gear doors open, such a condition is a common occurrence during a test flight and even more common during the first flight of a new aircraft. Ultimately, while this minor issue was encountered, the redundancy in the landing gear system was tested successfully in flight.

Naturally, the gear was inspected after landing and the system will obviously be tested once again when ZA002 flies again. One anomaly on a first flight is hardly indicative of a larger issue. If this same problem is found in the other test aircraft, then that would be something requiring a larger change, but there’s absolutely no evidence to support that after just five hours and six minutes of flying the 787.

21 Responses to Explanation and clarification on ZA002′s landing gear

  1. NickO December 22, 2009 at 6:34 pm #

    Those main gear doors looked like they were touching the ground- Pretty darned close if they weren’t…

  2. Szymon Dembowy December 22, 2009 at 7:34 pm #

    It actually looks like they tried to retract the MLG doors after touchdown. The doors went up to ~45deg. angle, moved around some and then went down again. I wonder whether it was intentional action by the pilots or a glitch in the system (computers trying to correct the problem of the doors in the incorrect position).

  3. josef December 22, 2009 at 7:43 pm #

    The doors were blown up from the engines going into reverse. I was standing even with the aircraft when it touched down and there was only inches between the doors and the ground.

    How about we just look at the simple stuff before we get worked up.

  4. bugref December 22, 2009 at 8:16 pm #

    in KPAE blogs, it did mentioned about floor vibration? how true was it?

  5. Szymon Dembowy December 22, 2009 at 8:18 pm #

    I did not get worked up. I was just asking a question. Did not think about the thrust reverse having that effect as I thought the doors would be locked in position and not be able to move by external forces.

  6. m in Seattle December 22, 2009 at 11:58 pm #

    A slightly different perspective as to why the MG landing doors were open

    http://seattletimes.nwsource.com/html/boeingaerospace/2010568452_secondflight23.html

  7. suland December 23, 2009 at 12:02 am #

    After watching the video I though about reverse that caused the doors to go up after being extended in-full.

  8. Daniel December 23, 2009 at 2:16 am #

    The main gear doors nearly touched the ground. What will happen if the plane is full packed an the landing is not as smooth as this one?

  9. John in CA December 23, 2009 at 10:03 am #

    You replace the doors if they scrape…..that is why they are attached with bolts….

    In either case, this is why they call it ‘flight test’.

  10. Trapperpk December 23, 2009 at 9:21 pm #

    Boeing stole this wing design for the 787 from these guys. Talk about deihedral and flexibility check out this design.

    http://www.hickerphoto.com/data/media/161/birds-flying_MG1135.jpg

  11. Onlooker December 24, 2009 at 7:21 am #

    I took a close look
    The MLG door actuator has no down lock in the ‘Free Fall Gear Extension’ mode but since it’s full of hyd. fluid at both head and cape ends with the valve at a bypass position, it acts as a shock strut rather than a down lock.
    Ground clearance is low, for an airplane without a pay load and little fuel that is scarry.

  12. Onlooker December 24, 2009 at 7:28 am #

    The wing up bend for an empty aircraft’s landing looks excessive to me.
    Any idea why the TE flaps were not retracte after landing?

  13. airplanejim December 25, 2009 at 3:55 pm #

    Trapperpk, your expertise on excessive wing bend is what? The wing bend is excessive as compared to what? Is it possible that the wing was designed to bend that much? And what was the GTOW of the 787 that causes you to think that the aircraft was “empty”. Test aircraft are never “empty”. They have test equipment on board to record everything the plane does and it isn’t weight free.

  14. keesje December 25, 2009 at 4:14 pm #

    “the redundancy in the landing gear system was tested successfully in flight”

    Well, congratulations.. Don’t become embedded..

  15. Trapperpk December 25, 2009 at 8:48 pm #

    Airplanejim

    I think you are repling to Onlooker not Trapperpk. I have no problem with its wing bend… I think it looks great just the way it is, the design is an advancement that composites bring to the table.

  16. Andrew December 27, 2009 at 5:15 pm #

    They undoubtedly had a little problem, but why no third man on board to go check things.
    Telemetry is all very well, but an extra pair of eyes could only be beneficial surely!

  17. Fritz December 28, 2009 at 2:29 pm #

    @Andrew

    It is my understanding that FAA rules prohibit anyone but the flight crew on board until they’re past the ‘experimental’ stage of flight testing.

  18. Andrew December 29, 2009 at 12:17 am #

    Thank you Fritz.
    Very different to Europe.
    There were 5 or 6 engineers on the A380 maiden flight.
    I would have thought an engineer as an observer would have constituted “flight crew”?
    Does anyone know if 001 or 002 have pressurized yet please?

  19. Eric December 29, 2009 at 2:14 pm #

    Andrew,

    I think it is also more a Boeing rule. They want to minimize the amount of people on the plane until they have a good understanding on how it flies.

    As far as pressurization, they would most likely have to have pressurized the plane to fly to 15,000 feet, due to the fact that your body goes into hypoxia above 10K, and the FAA Mandates supplemental oxygen at 10K. and since we didn’t see any pictures of the pilots with canola’s that tends to show that they did pressurize the cockpit for all the flights so far.

  20. Rick January 5, 2010 at 10:01 am #

    I’m an engineer at Boeing on the 787.

    I’d like to give the Reader’s Digest version of the 787 wing flex.

    This design feature was first introduced on the 777. The idea was based on the leaf-springs on a car. As noted earlier – we could make a stiffer wing, but that adds tremendous weight and gains little aerodynamically. But the biggest advantage was the smoother ride in turbulence.

    With the advent of Carbon Fiber wings – the fatigue due to wing bending is eliminated so we decided to take full advantage of the wing flex for in-flight comfort and additional positive dihedreal stability.

    Again – think leaf springs on a car.

    Thanks,
    And Happy flying.

  21. Eric January 5, 2010 at 11:29 am #

    About the wing flex.
    Boeing should know this phenomenon.
    This wing looks to me like the wing of a fully loaded B-52.