ZA004 – Registration: N7874 – Serial No: 40693 – Final Assembly: 8/04/08
With Dreamliner Four’s first flight just hours away, Boeing’s 787 test fleet is about to get a big boost. While this is the third 787 to fly since December 15, 2009, ZA004 is the fourth in the fleet of six test aircraft being employed for the certification program. The aircraft will be flown on its maiden flight by Captains Heather Ross and Craig Bomben.
Powered by two Trent 1000 engines, ZA004, will start its flight test program with a departure from Everett, Washington a stop at Moses Lake then on to Boeing Field where the aircraft will be based along with ZA001 and ZA002.
During its time as a flight test aircraft, ZA004 will accumulate the third most hours in the test fleet as it validates the high-speed aerodynamic performance of the aircraft along with the nautical air mile or NAMs tests for establishing the fuel efficiency of the engines. Additionally, ZA004 will focus on ETOPS testing, though the bulk of that flying will be done by ZA002 as part of the systems functionality and reliability testing.
The fully instrumented aircraft will also be responsible for conducting a flight loads survey. Frank Rasor, director of flight test for 787, says that this aspect of flight testing allows Boeing to validate their assumptions and refine their models:
This is a test where we actually instrument the airplane to actually go back and validate that we have made assumptions based on wind tunnel data, other information about what the actual load is going to be on the wing, on the tail, on the vertical surface. Then we plug those surveys, we actually instrument the airplane and go see if we are seeing those pressures or loads. The results of that test feed back to deciding “did we make the right assumptions in our model?” If not, do we have to make some small adjustments? It then leads up to the certification.
As the year rolls on, ZA004 will take part in “community noise” tests at a remote site like Glasgow, Montana – or equivalent airport – where there is very little air traffic. The test will see microphones laid out along the runway to establish the acoustic characteristics of the aircraft and its Trent 1000 engines. The same test will be duplicated on the GEnx-1B engines as well.
About two-thirds of the way through certification, ZA004 will come out of the flight rotation to have its Trent 1000s removed and replaced with the Package B engines that will provide a specific fuel burn (SFC) target within 1% of the original spec. The NAMs testing will be repeated with the new Package B engines to compare the fuel efficiency improvement.
“We have to do that test with pristine engines; engines that have not been abused in the test program,” says Rasor.
Because ZA004 will be heavier than production aircraft, Boeing is looking at repeating the NAMs tests for production aircraft with the Package B engines on Airplane 20 or 22, which will be instrumented with fuel sensors and a trailing cone for accurate airspeed information, adds Rasor.
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This post originally appeared at Flightglobal.com from 2007 to 2012.