Cirrus SR20 Pilot Operating Handbook page 360

Section 9 Cirrus Design
Supplements SR20
Electronic Stability and Protection (Optional)
When installed, Electronic Stability and Protection (ESP) assists the
pilot in maintaining the airplane in a safe flight condition. Through the
use of the GFC 700 AFCS sensors, processors, and servos, ESP
provides control force feedback, i.e. a "soft barrier", to maintain the
aircraft within the pitch, roll, and airspeed flight envelope by
automatically engaging one or more servos when the aircraft is near
the defined operating limit.
This feature is only active when in flight and the GFC 700 Autopilot is
off. The ESP engagement envelope is the same as the Autopilot
engagement envelope and is not provided beyond the Autopilot
engagement limits.
The pilot can interrupt ESP by pressing and holding the Autopilot
Disconnect (AP DISC) button. If frequent maneuvers are necessary
beyond the engagement threshold, such as commercial pilot training,
the system can be disabled from AUX/SETUP 2 page. Disabling will
cause the ESP OFF advisory to annunciate. The system can be re-
enabled from the same page, or is automatically re-enabled at the next
system power-up.
Pitch and Roll Modes
When the aircraft reaches the pitch and/or roll engagement limit, the
system commands the servos to apply a supplemental stick force back
toward the nominal attitude range. If the aircraft continues to pitch and/
or roll away from the nominal attitude range, stick forces will increase
with increasing attitude deviation until the maximum Autopilot
engagement limits are reached - at which point ESP will disengage.
ESP attempts to return the aircraft to the nominal attitude range not to
a specific attitude. As the attitude returns to the nominal range, the
stick forces and attitude rate change are reduced until the aircraft
reaches the disengagement threshold and ESP becomes inactive.
The disengagement threshold is sized so that the transition from ESP
being active to being inactive is transparent to the pilot.
Roll protection engagement limits are annunciated on the PFD as
double ticks at 45° roll attitude. If the aircraft exceeds 45° roll attitude
ESP becomes engaged and these indicators migrate to 30° roll
attitude denoting the disengagement threshold - the point at which
stick forces will be removed. No PFD annunciation is provided during
pitch ESP engagement.
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Revision 03: 09-08-14