After I started the APU, we used it to supply electrical power to start both main GEnx-1B70 engines simultaneously. A glance up at the overhead panel confirmed that knobs at 12 o'clock, and annunciator lights out, signified no problems. The electronic engine controls [full authority digital engine controls] handled all start functions.
It took very little thrust to move out of the chocks because the aircraft only was loaded to 70% of maximum ramp. Braking action was smooth and the tiller-controlled nosewheel steering precise. The rudder pedals command up to 8 deg. and the left and right tillers command up to 70 deg. of nosewheel steering.
Aligning the aircraft on Runway 13R, we pushed up the thrust levers midway, waited for the engines to stabilize at 40% N1 fan speed and engaged the auto-throttles. N1 stabilized at 94% as the engines produced their full 70,000-lb./takeoff thrust rating. With a 1:2.5 thrust-to-weight ratio, the lightly loaded aircraft had rather sporty acceleration.
Light back pressure on the yoke produced crisp but smooth pitch response. I followed the flight director cue in the head-up display to hold 10 deg. nose up. The test card called for me to engage the autopilot after retracting the gear and flaps. But, I elected to fly the aircraft by hand, using the HUD as the primary flight reference, for almost all my time in the left seat in order to evaluate the aircraft's handling qualities to the fullest.
Trimming for changes in airspeed takes just one touch of the trim switch to reset the trim reference airspeed. This does not directly move the horizontal stabilizer. Rather, the FBW system initially moves the elevators to change the trim and then follows up with stab trim to minimize trim drag. The control yoke does not change position with trim actuation.
Roll control, fully managed by the primary flight control computers, was silky smooth and nicely responsive, but not overly so. The FBW system provides artificial spiral stability up to 35 deg. of bank. There are no hard bank limits, so the aircraft can be rolled much steeper. But when the yoke is released, the FBW system forces the control wheel in the opposite direction to reduce bank angle to 30 deg.
Bryan also demonstrated how the P-beta function prevents thrust asymmetry or other uncommanded event from upsetting the aircraft in roll or yaw. In a stable 30-deg. bank angle, he retarded one throttle and advanced the other. The thrust asymmetry produced only the slightest change in yaw and virtually no change in roll angle. He repeated the process by reversing each throttle position. The result was the same. No upset, but enough seat-of-the-pants feel to detect the thrust asymmetry.
It is extremely unlikely that flight crews would ever experience a failure of the primary flight control computers that could cause the aircraft to be uncontrollable, but the engineers installed a switch in the overhead panel that allows pilots to disable the computers if they malfunction. Bryan then switched off the primary flight control computers so we could fly the aircraft using direct law. This enables the yoke and rudder pedals directly to command the positioning of the flight-control surfaces. The aircraft is completely controllable, but control response is comparatively crude and there are no flight envelope protections available.
The 787 also has protection against pitot/static system failure, such as an icing blockage. Switching to alternate air data enables the aircraft to compute airspeed and altitude from aircraft weight, configuration, AOA and 3-D GPS position. Using alternate air data, Bryan noted only a 8-9-kt. difference in airspeed and a 40-ft. variance in altitude while cruising at 300 KIAS and 16,000 ft.
We then proceeded to Moses Lake-Grant County for pattern work. We deliberately stayed high prior to descending for the instrument landing system (ILS) approach to Runway 32 so Bryan could demonstrate the aircraft's new autodrag function. The aircraft is so clean that it is difficult to descend to and capture glideslope or glidepath from above, even with gear down, flaps set to 25 or 30 deg. and idle thrust. Under these conditions, the autodrag function deflects the ailerons downward and two outermost spoilers on each wing upward to assist in descending without gaining airspeed. The function is phased out gently below 500 ft. above ground level so that normal flare and landing behavior is not affected.