Aircraft third to fly in test programme, but first to incorporate standard design changes
Embraer is preparing to conduct the final wing/fuselage join of the first production-representative 190 and plans to introduce the aircraft into the test programme in July.
The aircraft will join the second 190, which entered the test programme on 9 May, and the first prototype, which made its maiden flight on 12 March. A fourth and final aircraft is to enter the test programme in September.
Unlike the first two airframes, the second pair incorporate production-standard structural changes to the horizontal stabiliser, which was extended late in the design process to improve pitch authority. The changes came as a result of flight-test experiences on the smaller 170, which recently entered service.
Although Embraer originally planned to use identically sized empennages for both the 170 and 190 models for production commonality, flight tests proved the need for changes with the stretched variant. To allow flight tests to proceed on schedule, Embraer modified the tips of the stabilisers on the first 190 with bolt-on 1m (3ft) extensions, while retaining the baseline structure and original elevators.
"We took the 170 empennage and added tips, but these are not representative, so we redesigned them with the proper thicknesses in span and skins," says development programme director Mauro Kern, who adds that the changes increase horizontal tail area by around 10%.
The first two aircraft are now both based at the Gaviao Peixoto test site, with aircraft number one undergoing flight-control system software modification before restarting envelope-expansion and flying-qualities work. The second aircraft is being used to test in-flight thrust attenuation and will eventually be used for system tests and natural icing certification. The third aircraft, being production standard, will be "devoted to areas such as high-speed buffet work and will perform the actual certification tests for dive speed and so on", says Kern. The fourth 190 will be the first with a full interior and will be used for function and reliability work.
Embraer hopes to certify the 190 in July 2005 after a test and certification programme that is expected to take up to 1,700h, compared with around 3,000h for the 170. Aside from "first of model" tests, the latter was longer than expected because of the undercarriage collapses on the 170, which have effectively been cured with the addition of passive dampers to prevent shimmying of the undercarriage torque links.
These lessons have also been applied to the 190, says Kern. "We did a lot of undercarriage tests before first flight to assess the stability of the gear and we're very happy with the results," he says.
GUY NORRIS / SAO JOSE DOS CAMPOS
Source: Flight International
