Section 3 In-Flight Procedures
3-5
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
During an underspeed or overspeed
alert, the 3100 vertical mode display
does not change, but
ALERT
flashes to
indicate envelope speed protection has been triggered and the vertical
mode is no longer active. Roll mode remains engaged, but the roll
commands are reduced by half during envelope speed protection.
Figure 3-3:
ALERT
The
underspeed
alert activates if the aircraft speed reaches the low speed
limit, which triggers an audible alarm followed by an “Airspeed, Airspeed”
voice alert. The 3100 automatically commands the aircraft to pitch down in
order to increase airspeed to the underspeed recovery limit.
To recover the aircraft from an underspeed alert:
1) Press CWS switch (§ 3.9.1) and then increase aircraft speed beyond
the underspeed recovery limit as stated in the AFMS.
2)
If required, manually fly back onto the desired course, then release
CWS to let the 3100 resume the previously active pitch and roll modes.
The
overspeed
alert activates if the aircraft speed reaches the high
speed limit, which triggers an audible alarm followed by an “Overspeed,
Overspeed” voice alert. The 3100 automatically commands the aircraft to
pitch up in order to decrease airspeed to the overspeed recovery limit.
To recover the aircraft from an overspeed alert:
1) Press CWS switch (§ 3.9.1) and then reduce aircraft speed below the
overspeed recovery limit as stated in the AFMS.
2)
2) If required, manually fly back onto the desired course, then release
CWS to let the 3100 resume the previously active pitch and roll modes.
3.6.3.1. Active Envelope Protection on Approach
During an ILS or GPS approach with AP engaged, active envelope
protection operates until 1000 feet below glideslope capture point. Once
the glideslope has been captured, indicated by
GS
or
GPSV
displayed as
the active pitch mode, the 3100 remains in active envelope protection until
the aircraft has descended 1000 feet below the initial capture point and
then transitions to passive envelope protection for the remainder of the
approach.
It is recommended to capture the glideslope at 1500 feet AGL so the
envelope protection transition from active to passive occurs at 500 feet
