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.
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.