AOPA Turbine Pilot Magazine - April 2015 - T-11

FLY BY WIRE

A NINE-SEAT cabin by Embraer
and BMW Designworks USA is the
most popular option, with forward
club seating and an aft divan
(left). Honeywell's Ovation Select
cabin management suite includes
a full HD video system and media
inputs for portable devices. For
voice connectivity there's Wi-Fi
and either the Inmarsat, Aircell,
or Iridium platforms. The Pro Line
Fusion avionics suite (below) has
four screens, many integrated
functions, and databases can be
updated quickly using Wi-Fi.

A big part of Embraer's Legacy 500 leapfrog
strategy is fly-by-wire (FBW) flight controls.
With FBW, there are no cables, pulleys, bellcranks, pushrods, or any other mechanical
connections between the cockpit and primary control surfaces. Instead, digital
commands from the cockpit flight controls
pass via digital data buses to a primary flight
control computer, then on to hydraulic actuating units at the control surfaces.

the airplane enters flight mode, which puts
path control as a priority.
Prior to landing, and with gear down
and flaps 3 (full down), normal law puts
you in what Embraer calls trim control
system (TCS) trim mode. This is designed
to give the pilot a traditional trim feel. As
the airplane slows, the pilot can retrim in
pitch using a TCS button on the sidestick.
Press the button, and the airplane will trim
to the airspeed that exists before the button

For an airplane of its weight and size, the
Legacy 500 responds far more nimbly
than I anticipated.
The flight control computer, which
has two modes, does more than pass along
commands and follow the autopilot. In
normal mode, flight control laws automatically provide flight envelope protection
and auto-trim functions, maintain the airplane's flight path, and can even command
a zero-sideslip condition in the event of an
engine-out situation.
The normal-law flight envelope limits
bank to 35 degrees, and pitch to plus 30/
minus 15 degrees. Airspeed limits are 1.13
VSO and VMO. There's automatic pitch and
yaw compensation in turns, and automatic
roll compensation in a sideslip-so yaw/roll
coupling is suppressed.
If any of the envelope protection functions are lost-events which Embraer says
would have a one-in-a-billion chance of
happening-the system reverts to direct
mode. Now the airplane has no envelope
protection, and flies like a conventional
airplane.
Under normal control law, there
are sublaws for takeoff and landing. For
example, during the takeoff run, the steerby-wire system limits nosewheel travel
from 62 degrees of travel (at low speeds)
to a mere three degrees as speed builds.
At 65 knots, the airplane goes into takeoff
mode, which brings on a pitch rate control that dampens pitch after takeoff so
there's a smooth pitch capture as the airplane rotates. Three seconds after takeoff,

is activated. As pitch or airspeed changes
coming down final, the pilot will feel the
typical need to pull or push on the sidestick, but pressing the TCS will trim out
the control pressures the same way a conventional, manual pitch trim input would.
Speaking of sidesticks, they self-center
with hands off and use a spring mechanism
to provide a measure of artificial control
feel. The sticks are not mechanically connected, and the Legacy 500 uses a system
that warns pilots when both are making
control inputs at the same time. Both sticks
vibrate, and aural and visual "dual input"
callouts occur. Pressing the AP/PTY button on the sidestick gives control to the last
pilot who pressed it.
STRAPPING IN

Embraer calls the Legacy 500 a mid-size
jet, but walk up to it and the impression
is one of a much larger airplane. Go up
the airstair door, hang a left through the
galley, and you'll see an expansive cockpit, made all the more so by the absence
of centrally located control yokes. The
windshields give you a great wraparound
view, but it's the Rockwell Collins Pro Line
Fusion avionics suite that dominates the
scenery inside. Synthetic vision includes
transparent airport domes for the departure, destination, and alternate airports,
plus magenta lead-in lines to the selected
landing runway.
www.aopa.org/pilot AOPA PILOT | T-11
http://www.aopa.org/pilot
AOPA Turbine Pilot Magazine - April 2015

Table of Contents for the Digital Edition of AOPA Turbine Pilot Magazine - April 2015
