RC501 has relocated to Moses Lake after a late afternoon (38min) flight on Monday afternoon that delayed the morning departure due to minor troubleshooting on engine number one. The aircraft reached an altitude of just over FL240 and spent much of the flight conducting tests if the aircraft's flight controls. The aircraft will spend its initial airworthiness trials and flutter testing at Grant County International before transferring to Palmdale, California, at which point RC521 and RC522 will join the flight test program.
ZA001 is set to return to the sky after 2 PM PT for what is likely to be day six of flutter testing. ZA004 may commence taxi tests as early as Tuesday afternoon with first flight as early as Wednesday.
A few more details have emerged about Friday's Boeing "uncommanded loss of power" that occurred on one of the two engines. Boeing says that after the loss of power, the crew followed standard procedure and shut down the Rolls-Royce Trent 1000 during the diversion to Moses Lake. Additionally, Boeing also checked all the Trent 1000 engines on ZA002-ZA004. The findings of those examinations are not known to this blogger.
And for additional trans-Atlantic comparison, take a look at the following clip of A380's flutter testing regime in 2005 that saw the aircraft accelerate to mach .96 in a dive. Initially the aircraft's wing-to-body fairing failed structurally during the test around mach .92 and had to be redesigned. It's a good example of the challenges and unknowns that continue to come along with modern flight testing.