Boeing has obtained type inspection authorization (TIA) for the stretched 787-9 from the FAA, officially clearing the way for the start of certification flight testing.

The award of TIA marks a key transition in the test program which now moves from establishing the basic airworthiness of the 787-9 to the more detailed and comprehensive task of certifying it for airline use.

The milestone, which covered approval for the two Rolls-Royce Trent 1000-powered variants, comes as the overall flight test program passed 100 flights on Dec 10.

Together with the third 787-9, a General Electric GEnx-1B powered aircraft which joined the flight test program on Nov 19, the overall fleet has so far accumulated more than 285 flight test hours.

In all, five aircraft are slated for the program. The fourth and fifth 787-9s will be production aircraft with full interiors with ZB197, an aircraft destined ultimately for All Nippon Airways, scheduled to be the first of the pair to join the campaign. A Rolls-powered aircraft, ZB197 will be used principally for ETOPS and function and reliability tests as well as electro-magnetic effects (EME), which will check protection against lightning strikes. The fifth aircraft, ZB167 will be used for EME testing of the GE engine installation.

Boeing says it expects to obtain TIA for the GE-powered aircraft, ZB021 shortly. This is currently being used for airspeed calibration tests, while the first Rolls-powered 787-9 is undertaking basic flight control evaluation. Following last month’s evaluation in the McKinley Climatic Laboratory at Eglin AFB, Fla., the second Rolls aircraft, ZB002, has returned to Boeing’s Everett site where it is being used for ground evaluation of the extended lower lobe cargo system.

The derivative is 20 feet longer overall than the baseline 787-8, and is powered by the newly-certificated ‘Package C’ version of the Rolls-Royce Trent 1000 or the upgraded ‘PIP II’ variant of the General Electric GEnx-1B. TIA award keeps Boeing’s flight test schedule on track for delivery of the first 787-9 to launch customer Air New Zealand in mid-2014. Out of 1,012 787s currently booked by Boeing as firm orders some 396, or 39%, are 787-9s. The balance is made up of 496 787-8s and 120 787-10s.

EDITOR’S NOTE: This article was update to correct infomration about the fifth aircraft. The customer for this aircraft has not been named.