This past weekend it was expected that Boeing was to fly all four 787 (ZA001, ZA002, ZA003, and ZA004). Both Guy Norris and Flightblogger reported this. This would have marked the first time that all four test airplanes would have flown and hopefully it will allow Boeing to start accumulating more test flight hours. Unfortunately, only ZA001 flew during this past weekend.
According to Guy Norris, ZA002 flight that was expected to take place on Saturday is now scheduled to fly on Monday, April 12th as Boeing wanted to conduct more ground tests on the aircraft which has new flight control software installed. It is flight testing of this new version of the software that will allow the FAA to issue the TIA (Type Inspection Authorization) and allow certification flight testing to proceed. The TIA was expected at the end of March and that was delayed from mid February. If the TIA is issued by the middle of April then the 787 program would have lost an additional 1/2 month of schedule margin.
ZA003 second flight was to have taken place yesterday, April 11th but it did not fly. The reason is unknown but this test flights are to signal the start of environmental control systems testing on board that aircraft as well as testing other systems on the aircraft including the RAM air systems.
ZA004 is going into a planned layup and will not fly until the end of April at the earliest. ZA001 is finishing up the last of stability and control flight tests and will now focus on low speed performance flight testing.
According to my accounting, The Boeing test fleet has accumulated almost 460 test flight hours as of April 11th. On April 9th, ZA004 flew the longest 787 test flight to date which is 6 hours and 40 minutes.
Flightblogger also reported on a potential problem with stringers in the rear of the 747-8 upper lobe (hump). The flange of the stringers may be to thin to handle the loads and thus would need to be replaced. Boeing and Vought (contractor) are studying the issue which may need to be resolved by replacing the stringers in question, a costly and time consuming process. Flightblogger says that the 747-8 in the test flight program would continue test flight under restrictions on their g-loads but they would continue. He says that the 747-8 is now entering flutter testing. So far I've show that the 747-8 program has accumulated just under 108 flight hours through April 11th. Flightblogger says that Boeing is thinking about using on of the production aircraft to augment the 747-8 test fleet. This aircraft would not be instrumented for the test flight program like the other three aircraft are but would perform engineering flight tests. The aircraft under consideration is RC503 which is the second production aircraft and is currently in the paint hangar at Everett.
Read Guy's and Jon's articles here:
Flightblogger: 747-8F begins flutter testing as stringers get inspected (and other 787 items)
Guy Norris: Big Weekend for 787
Guy Norris: 787 Update
Now speaking of structural strength, Daniel Tsang of Airways Aviation News put out an interesting article on the side of body fix on the 787. As some of you may know, Boeing had to fix the side of body area due to that area being too weak to handle flight loads. The fix has been installed on 9 air frames and needs to be installed on another 8. All 787s going forward would have the side of body fix installed at the sub contractor prior to delivery to Everett though there would be some installation work to be done on the final assembly line prior to the wing-body join. It is expected that starting with LN 49, the parts that strengthen the side of body would not be needed as Boeing and it sub contractors would have redesigned those areas of the aircraft (the wing box and the center wing box) that would provide the additional strength needed and the installation of the parts would not be necessary. Daniel Tsang is reporting that the use of the parts that provide the reinforcement to the side of body would be a permanent solution though Boeing is looking to simply the production and installation of the parts by tweaking the design. You can read Daniel's article:
Daniel Tsang: Boeing looking at ways to simplify side-of-body modification
Boeing is continuing to make its production milestones. ZA175 (LN 20) started final assembly on March 31st. This aircraft is a major milestone as it introduce a major blockpoint change which incorporates weight saving measures into the 787. ZA531 (LN 16) which is the second 787 for LAN came out of the paint shop painted all white (not in LAN color scheme as had been expected). Today there will be a line move as ZA176 (LN 21) will start final assembly. ZA150 (LN 17), the first aircraft for Royal Air Maroc, will be moved into the paint hangar though I don't know if it'll be painted in RAM colors. There will be another line move on April 26th when ZA115 (LN 22) will start final assembly. At that pace Boeing will be assembling 787s at a 2.5 per month clip which is what they had been expecting. I expect that Boeing will start final assembly on ZA177 (LN 23) and ZA116 (LN 24) in May.