With engine sensor tests now apparently completed to its satisfaction following this weekend’s hiatus, Boeing is set to resume 787 flight tests tomorrow – possibly to include ZA004 for the first time. The news comes as the first 747-8F, RC501 conducts its second flight – taking off from Paine Field at 4.10 pm this afternoon, en-route to its temporary base at Moses Lake. The aircraft is still airborne as I write this blog, and was expected to be flying in company with a Boeing T-38 chase aircraft for at least the second half of today’s sortie.
Boeing isn’t saying too much yet about the engine pressure sensor incident which forced ZA001 to stay at Moses Lake for most the weekend, but the fact the aircraft is now scheduled to resume flutter testing tomorrow appears to indicate the issue is basically behind it.
ZA002 is scheduled to continue stability and control tests tomorrow with a focus on longitudinal flight control characteristics. A slew of ground tests are also in work while ZA002 is not flying at the moment including tests of the tank inerting system together with associated temperature measurements of the fuel, and – possibly later this week – some ground work in readiness for flight evaluations of the trailing edge variable camber system (TEVC).
The TEVC cleverly articulates the trailing edge of the flaps in various cruise conditions to help reduce drag. The system was originally designed to work by deflecting the flap by very small (0.5 deg) increments for a total travel of around 3 deg (1.5 deg up or down), though the final version developed for flight tests may vary slightly. Either way, the TEVC represents the first steps taken by Boeing, or anyone else for that matter as far as I know, towards a practical application on a commercial jet of a ‘morphing wing’ and is another of the many technologies which the company rolled into the 787 in search of significant fuel-burn savings.
More than just a pretty picture? 787's soon-to-be-tested 'morphing' trailing edge. (Guy Norris)
The first flight of ZA004 is meanwhile tentatively re-set for tomorrow having been put back from today for unknown reasons.
I just checked and according to Flightaware, RC501 is still boring holes through the skies of central Washington State. More updates to follow.
UPDATE: Boeing confirms the engine pressure sensor glitch was a hardware problem associated with one specific unit, and was not an issue with the electronic engine control unit or any of the control software. It also says that the sensors on the other Trent 1000s in the flight test fleet, including those on ZA002 and ZA004 were checked as a precaution - hence the hold to first flight of ZA004.
RC501 meanwhile arrived safely at Moses Lake at 5.45 pm according to Flightaware.