Mixed news for Boeing first thing Monday as the 747-8 returns to flight, while the 787 team continue to troubleshoot engine issues which have forced the postponement of flutter tests.
First flight of ZA004 – the next 787 scheduled to join the test program - was also scheduled to take place later today but as of late Sunday, there appeared to be some fresh uncertainty as to whether this would in fact proceed.
The 747-8 is scheduled to fly to Moses Lake where it will be temporarily based while conducting initial airworthiness tests before moving south to Palmdale, Calif., for the bulk of the certification effort. Boeing originally filed a flight plan calling for a 7 am departure from Everett, but later on Sunday revised the expected flight time to sometime after 9 am.
The issues with the 787 cropped up on ZA001 during the fifth day of flutter tests on Friday. Writing in his blog, Boeing Commercial marketing vice president Randy Tinseth says during the flight the crew experienced “an uncommanded loss of thrust in the one of the engines,” and landed at Grant County International airport (AKA Moses Lake). “Teaming with Rolls-Royce, we determined that the issue had to do with a pressure-sensing component within the engine. We located replacement parts and then got the parts and the right crew to Moses Lake - beginning the maintenance activity on Saturday. Later that day, we ran the engines to confirm that the replacement had been done correctly and that there were no anomalous readings.”
The aircraft ferried back to Boeing Field where, according to All Things 787, some maintenance work was observed being undertaken during Sunday on the right Trent 1000. This work appears to be taking longer to conclude than hoped as late Sunday evening Boeing took the decision to slide the 6th flutter test flight (originally re-scheduled to Monday), and to conduct further ground tests later today.
Trent 1000 on ZA003 as viewed from the cabin (Guy Norris)
For ZA004 the situation remained uncertain going into Sunday night, the test crew earlier that day having successfully cleared the aircraft for first flight later today. As I write this it is not yet known if the engine sensor tests on ZA001 may have forced a precautionary delay to the first flight of ZA004. The second aircraft, ZA002, is meanwhile due to undertake taxi tests on Monday, some of which are believed to be associated with nose gear steering evaluations.