Boeing 777-9 certification tests reached a key stage on Aug. 14 with the return of WH001, the first 777X development aircraft, to Edwards AFB, California, for the start of takeoff performance testing.
Based out of nearby Victorville, California, the tests are a repeat of
Boeing development work initially conducted at Edwards in 2022 and form a significant part of the overall certification campaign which has been underway since the granting of FAA type inspection authorization in June 2024.
Takeoff performance certification testing validates acceleration, rotation, climb capability and minimum safe lift-off speed, also known as minimum unstick speed or Vmu. The work “defines the numbers that we need that are used by airline pilots for every day for the life of the fleet,” says 777X chief pilot Ted Grady.
Discussing Vmu testing, Grady adds, “that's where we intentionally put the tail of the airplane on the runway gently, and then we'll show that the airplane can fly away with that three-point stance of the main gear and the tail on the airplane—it's a very precise maneuver to fly.” Commenting about the tests on a
Boeing video, Grady says Vmu testing “sometimes takes several attempts, but out of that we'll get the data needed to show the airplane performance capability is what we have told the regulators and our customers.”
Prior to flying to California, WH001 had been back in
Boeing Field, Seattle, for a short period of maintenance following an intensive period of brake testing in Roswell, New Mexico.
Meanwhile, the second 777-9, WH002, returned to the air on Aug. 17 with an aerodynamic certification test flight. The aircraft, which has been on the ground at Moses Lake, Washington, since mid-July, has been undergoing unspecified reconfiguration work prior to rejoining the test campaign,
Boeing says.
WH003, the third 777-9, is continuing engine inflight restart tests across a range of altitudes and airspeed conditions, while WH004 is in Yuma, Arizona, primarily for ground tests of the aircraft’s environmental control system.
The fifth 777-9 test airframe, WH286,
which made its first flight on Aug. 5, was flown to Marana Pinal Airport, Arizona, on Aug. 13 for the start of high-intensity radiated field (HIRF) testing. HIRF certification tests validate the electromagnetic immunity of aircraft systems to strong radio frequency signals and protection against lightning.