After the cumulative effect of design changes added six-months to the first delivery of the first 747-8 freighter, Boeing appears to have found a more steady pace with the acceleration of its flight testing.
The company is nearing 1,500h of flight testing on the fleet of four, which began testing on 9 February of this year.
Boeing announced on 30 September it would slide first delivery to Cargolux to the middle of 2011, following required design changes to the aircraft's inboard aileron actuators, main landing gear doors, nose landing gear wheel well and flight control laws to dampen out an oscillation.
"We made significant progress in resolving the issues we found during the flight test programme," says Michael Teal, 747-8 chief project engineer. "We have implemented fixes on the airplane and we're now driving toward all of the fundamental testing we have to complete to certify and deliver the airplane."
In August, Boeing undertook additional stall testing, continuing stability and control evaluations of the aircraft's low-speed handling characteristics.
In October, the 747-8F completed ground effects testing to collect data on the low altitude performance of the aircraft close to the runway to better refine the aircraft's autoland system.
In November, RC501, the lead freighter test aircraft completed velocity minimum unstick testing to determine the edge of the takeoff performance envelope by dragging the aircraft's tail on the runway during its takeoff roll.
Additionally, Boeing bested its own maximum take off weight record of 455,860kg (1,005,000lbs) from from June by loading the 747-8F to a take off weight of 458,128kg, 15,875kg higher than the 442,252kg MTOW.
RC501 is currently in layup, say programme sources, preparing for its flight loads survey in January. The aircraft is having pressure taps and strain gauges installed throughout the airframe to compare computer assumptions against observed performance.
RC521, the second test aircraft, will begin artificial ice shapes testing later in December, and is currently in lay up as well as to have the epoxy foam shapes installed on the leading edges of the wings, horizontal and vertical stabilisers.