Genesys S-TEC 3100 Owner's manual

S-TEC 3100 Digital and Analog
Flight Control System
S-TEC 3100
Digital and Analog
Flight Control System
Pilot Guide
PRECISE PERFORMANCE.
PROVEN EXPERIENCE.
PERSONALIZED ATTENTION.

S-TEC 3100 Digital and Analog
i2nd Ed Aug 2019 S-TEC 3100 Digital and Analog
Pilot Operating Guide
and Reference
Digital Flight Control System
S-TEC 3100 Digital and Analog
Doc No 87325
This pilot guide must be carried in the aircraft and available to the
pilot at all times. It can only be used in conjunction with the Federal
Aviation Administration (FAA) approved Aircraft Flight Manual (AFM)
or Aircraft Flight Manual Supplement (AFMS). Refer to the applicable
AFM or AFMS for aircraft specic information, such as unique ground
tests, limitations, and emergency procedures.
© 2019 Genesys Aerosystems. All Rights Reserved.
Information contained in this document is subject to change without notice.
No part of this document may be reproduced in any form, or by any means,
without prior written consent of Genesys Aerosystems.
Printed in the United States of America. Genesys Aerosystems and S-TEC
logo are registered trademarks of Genesys Aerosystems. All other brand
names and trademarks are the property of their respective holders.
For service or repairs, contact an authorized Genesys Aerosystems
dealer. For product support, contact Genesys Aerosystems.
One S-TEC Way, Municipal Airport, Mineral Wells TX 76067
Phone: [phone] Fax: [phone]
www.genesys-aerosystems.com

S-TEC 3100 Digital and Analog
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
ii
Revision Record
Retain this record in front of guide.
Revision
Number Revision Date Notes/Pages changed, added, or deleted by current revision
1st Ed. February 2018
Rev A November 2018
2nd Ed. August 2019

S-TEC 3100 Digital and Analog
iii2nd Ed Aug 2019 S-TEC 3100 Digital and Analog
Table of Contents
Section 1 Overview
1.1. Document Organization.................................................................. 1-1
1.2. Purpose .......................................................................................... 1-1
1.3. General Control Theory .................................................................. 1-1
1.4. Limitations ...................................................................................... 1-2
1.4.1. Altitude Pre-Select Limitations .............................................. 1-2
1.4.2. Indicated Airspeed Mode (IAS) and Envelope Protection
Limitations........................................................................................ 1-2
1.4.3. Optional Yaw Damper (YD)................................................... 1-2
1.5. Autopilot Modes.............................................................................. 1-3
1.6. System Components ...................................................................... 1-4
1.6.1. S-TEC 3100 Flight Guidance Computer (FGC) .................... 1-4
1.6.2. Aircraft Conguration ............................................................ 1-4
1.6.3. Interface Conguration.......................................................... 1-5
1.6.4. Servo Assemblies ................................................................. 1-5
1.6.5. Sandia Air Data Computer .................................................... 1-5
1.6.6. GPS 1/2 Selector Switch....................................................... 1-5
1.7. Interfaced Avionics ......................................................................... 1-6
1.7.1. Garmin G500/G600/TXi EFIS ............................................... 1-6
1.7.2. Aspen EFD 500/1000/MAX ................................................... 1-6
1.7.3. Avidyne EXP5000 and Meggitt EFIS .................................... 1-7
1.7.4. Analog DG/HSI...................................................................... 1-7
1.8. Display Legend............................................................................... 1-8
Section 2 Pre-Flight Procedures
2.1. Power-Up Test ................................................................................ 2-1
2.2. Pre-Flight Checks........................................................................... 2-2
Section 3 In-Flight Procedures
3.1. Engaging the Autopilot.................................................................... 3-1
3.1.1. Roll Attitude (ROLL) Mode .................................................... 3-1
3.2. Disconnecting the Autopilot ............................................................ 3-1
3.3. Autopilot (AP) Operation................................................................. 3-2
3.4. Flight Director (FD) Operation ........................................................ 3-2
3.5. Yaw Damper (YD) Operation.......................................................... 3-3
3.6. Envelope Protection ....................................................................... 3-3
3.6.1. Envelope Speeds for FIKI Aircraft......................................... 3-4
3.6.2. Passive Envelope Protection ................................................ 3-4
3.6.2.1. Passive Envelope Protection on Approach.................. 3-4
3.6.3. Active Envelope Protection ................................................... 3-4
3.6.3.1. Active Envelope Protection on Approach..................... 3-5
3.6.4. “AP ICE SPEED” (FIKI Aircraft Only) .................................... 3-6

S-TEC 3100 Digital and Analog
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
iv
3.7. Lateral Modes................................................................................. 3-6
3.7.1. Roll Hold (ROLL) Mode......................................................... 3-7
3.7.2. Heading (HDG) Mode ........................................................... 3-7
3.7.3. Navigation (NAV) Mode ........................................................ 3-7
3.7.3.1. Tracking a VOR (NAV)................................................. 3-8
3.7.3.2. GPS Steering (NAVGPSS) Mode .................................... 3-9
3.7.4. Approach (APR) Mode .......................................................... 3-9
3.7.4.1. VOR Approach (APR)................................................ 3-10
3.7.4.2. ILS Approach (APRLOC)...............................................3-11
3.7.4.3. GPS RNAV Approach (APRGPSS/APRGPSL)................. 3-12
3.8. Vertical Modes.............................................................................. 3-14
3.8.1. Pitch Attitude (PITCH) Mode............................................... 3-14
3.8.2. Indicated Airspeed (IAS) Mode ........................................... 3-15
3.8.3. Vertical Speed (VS) Mode................................................... 3-15
3.8.4. Altitude Hold (ALT HOLD) Mode ......................................... 3-16
3.8.5. Altitude Pre-Select .............................................................. 3-16
3.8.5.1. No Altitude Pre-Select (Manual Altitude Capture)...... 3-17
3.8.5.2. S-TEC 3100 Internal Altitude Pre-Select ................... 3-18
3.8.5.3. S-TEC ST 360 Altitude Selector/Alerter..................... 3-19
3.8.5.4. Garmin G500/G600/TXi Pre-Select ........................... 3-19
3.9. Additional Modes .......................................................................... 3-20
3.9.1. Control Wheel Steering (CWS) Mode ................................. 3-20
3.9.2. Go-Around (GA) Button ...................................................... 3-21
3.9.3. Take-O󰀨-Go-Around (TOGA) .............................................. 3-21
3.9.4. Level (LVL) Mode ................................................................ 3-22
3.9.4.1. Emergency Level Mode............................................. 3-22
3.9.5. Half Bank (HB) Mode .......................................................... 3-23
3.9.6. Menu (MNU) Button ............................................................ 3-23
3.9.7. Maintenance Mode ............................................................. 3-24
3.10. Trim............................................................................................. 3-24
3.10.1. Automatic Trim Annunciations........................................... 3-24
3.10.2. Manual Trim Annunciations............................................... 3-25
3.10.3. Manual Electric Trim ......................................................... 3-25
3.10.4. Automatic Trim Disable ..................................................... 3-25
Section 4 Emergency Procedures
Section 5 Operating Parameters
5.1. Roll Axis Limits ............................................................................... 5-1
5.2. Pitch Axis Limits.............................................................................. 5-1
5.3. Level Mode Recovery..................................................................... 5-1
5.4. Envelope Speed Limits................................................................... 5-1
Section 6 Glossary

S-TEC 3100 Digital and Analog
v2nd Ed Aug 2019 S-TEC 3100 Digital and Analog
List of Figures and Tables
Figure 1-1: S-TEC 3100 Without Optional Yaw Damper ........................ 1-2
Figure 1-2: S-TEC 3100 Flight Guidance Computer (FGC) ................... 1-4
Figure 1-3: S-TEC 3100 Servos ............................................................. 1-5
Figure 1-4: Sandia SAC7-35 .................................................................. 1-5
Figure 1-5: Display Legend .................................................................... 1-8
Figure 3-1: Roll Attitude (ROLL) Mode ................................................... 3-1
Figure 3-2: Without Optional Yaw Damper Installed............................... 3-3
Figure 3-3: ALERT.................................................................................. 3-5
Figure 3-4: Roll Attitude (ROLL) Mode ................................................... 3-7
Figure 3-5: Heading (HDG) Mode .......................................................... 3-7
Figure 3-6: VOR Approach ....................................................................3-11
Figure 3-7: Straight-In ILS Approach.....................................................3-11
Figure 3-8: RNAV Approach Procedure................................................ 3-13
Figure 3-9: Pitch Attitude (PITCH) Mode.............................................. 3-14
Figure 3-10: Indicated Airspeed (IAS) Mode ........................................ 3-15
Figure 3-11: Vertical Speed (VS) Mode ................................................ 3-15
Figure 3-12: Altitude Hold (ALT HOLD) Mode ...................................... 3-16
Figure 3-13: Altitude Pre-Select............................................................ 3-16
Figure 3-14: No Altitude Pre-Select...................................................... 3-17
Figure 3-15: Target Altitude in ft. with ALT HOLD Mode Armed............ 3-18
Figure 3-16: S-TEC ST 360 Altitude Selector/Alerter, 3100 Display..... 3-19
Figure 3-17: Target Altitude Not Displayed ........................................... 3-19
Figure 3-18: Control Wheel Steering (CWS) Mode .............................. 3-20
Figure 3-19: Go-Around (GA)............................................................... 3-21
Figure 3-20: Level Mode, Roll and Pitch Hold Modes .......................... 3-22
Figure 3-21: Emergency Level Mode; Servos Engaged, No AP........... 3-23
Figure 3-22: HB Mode Switch/Annunciator .......................................... 3-23
Figure 3-23: Mute Icons........................................................................ 3-24
Figure 3-24: Unmute Icon on 3100 Display.......................................... 3-24
Figure 3-25: Pitch Trim Annunciations.................................................. 3-25
Figure 3-26: Manual Electric Trim......................................................... 3-25

Section 1 Overview
1-12nd Ed Aug 2019 S-TEC 3100 Digital and Analog
Section 1 Overview
1.1. DOCUMENT ORGANIZATION
Section 1 Overview
Section 2 Pre-Flight Procedures
Section 3 In-Flight Procedures
Section 4 Emergency Procedures
Section 5 Operating Parameters
Section 6 Glossary
1.2. PURPOSE
This pilot guide provides pre-ight and in-ight operating procedures for the
S-TEC 3100 autopilot (3100) for both digital and analog interfaced systems.
NOTE:
The S-TEC 3100 is designed to assist pilots with cockpit workload
management. The ability of the 3100 to provide optimum assistance
and performance is directly proportional to the pilot’s knowledge of its
operating procedures. Therefore, it is highly recommended that the pilot
develop a thorough understanding of the 3100, its modes, and operating
procedures in visual meteorological conditions (VMC) prior to using it
under instrument ight rules (IFR).
1.3. GENERAL CONTROL THEORY
The S-TEC 3100 is capable of being a two- or three-axis attitude-based
digital ight control system. It is comprised of a computer/programmer,
which performs input/output processing and control laws, and an integrated
bezel/display for mode selection and display, including trim annunciations.
S-TEC servos are coupled to the control system:
Roll Servo: Coupled to the ailerons. The 3100 senses roll attitude, roll rate,
heading error, and course deviation to control the roll servo.

Section 1 Overview
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
1-2
Pitch Servo: Coupled to the elevator. The 3100 senses pitch attitude,
pitch rate, pressure altitude, indicated airspeed (IAS), vertical speed (VS),
vertical acceleration, and glideslope deviation to control the pitch servo.
Trim Servo: Coupled to the elevator trim. The 3100 senses an out of
trim condition whenever the trim sensor in the pitch servo is activated. In
response, the 3100 drives the trim servo in the proper direction until the
aircraft is in trim.
Yaw Servo (optional): Coupled to the rudder. The 3100 senses yaw rate
and acceleration to control the yaw servo.
The 3100 also includes an altitude pre-select function, if enabled.
1.4. LIMITATIONS
1.4.1. Altitude Pre-Select Limitations
The S-TEC 3100 relies on digital air data information for altitude pre-select.
Some congurations may not have altitude pre-select if the baro-correction
cannot be provided to the autopilot system.
1.4.2. Indicated Airspeed Mode (IAS) and Envelope Protection
Limitations
The S-TEC 3100 relies on digital air data information for indicated air
speed hold (IAS). Some congurations may not have IAS mode if indicated
airspeed data is not provided to the autopilot system.
Overspeed and underspeed protection is not be available for systems
without indicated airspeed.
1.4.3. Optional Yaw Damper (YD)
Some aircraft congurations do not have a yaw damper system installed.
In these cases, the yaw damper button is blank and the YD LED does not
illuminate under any circumstances.
Figure 1-1: S-TEC 3100 Without Optional Yaw Damper

Section 1 Overview
1-32nd Ed Aug 2019 S-TEC 3100 Digital and Analog
1.5. AUTOPILOT MODES
Autopilot (AP) Mode: Engages autopilot servos
Flight Director (FD) Mode: Drives steering command bars (ight director
or electronic ight instrument system (EFIS) required)
Yaw Damper (YD) Mode: Dampens excessive adverse yaw and coordinates
turns (if installed)
Roll Attitude (ROLL) Mode: Holds roll attitude
Pitch Attitude (PITCH) Mode: Holds pitch attitude
Heading (HDG) Mode: Turns onto a selected heading and holds it
Navigation (NAV) Mode: Intercepts and tracks a VOR course
Approach (APR) Mode: Intercepts and tracks a LOC front course or GPS
approach inbound
Glideslope (GS) Mode: Intercepts and tracks glideslope
Level (LVL) Mode: Returns aircraft to level ight and a congured pitch
angle for the aircraft (refer to AFMS for pitch angle value)
Indicated Airspeed (IAS) Mode: Holds indicated airspeed
Vertical Speed (VS) Mode: Holds vertical speed
Altitude Hold (ALT HOLD) Mode: Holds altitude
GPS Steering (GPSS) Mode: Laterally steers along a ight plan course
dened by GPS/FMS
GPS Lateral Navigation (GPSL) Mode: Laterally steers along an approach
course dened by GPS/FMS approach
GPS Vertical Navigation (GPSV) Mode: Vertically steers along a glidepath
dened by a GPS/FMS approach
Reverse (REV) Mode: Intercepts and tracks a LOC back course (BC)
inbound or tracks a LOC front course outbound
Control Wheel Steering (CWS) Mode: Used to temporarily disengage
servos and manually maneuver the aircraft or set new targets
Go-Around Mode (GA) Mode: Disengages AP and/or engages FD in pitch
hold mode with a pre-set nose-up command

Section 1 Overview
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
1-4
Half Bank (HB) Mode: Reduces commands in HDG and GPS/FMS steering
by half (if installed)
Automatic Trim Mode: Automatically drives pitch trim servo.
1.6. SYSTEM COMPONENTS
1.6.1. S-TEC 3100 Flight Guidance Computer (FGC)
The S-TEC 3100 FGC is the main processing unit for the autopilot system.
It controls all of the input/output processing, control law calculation, and
drives up to four servos (pitch, roll, yaw and pitch trim).
Figure 1-2: S-TEC 3100 Flight Guidance Computer (FGC)
The FGC requires navigational and target data to provide the correct servo
drive signals. Mode selection may be controlled through the front panel.
The S-TEC 3100 has an on-board MEMS device that calculates attitude
angles and rates in the pitch, roll, and yaw axis. This may be congured
to act as the primary or single source of attitude on certain interface
congurations.
NOTE:
Each S-TEC 3100 is loaded with a single conguration le, which
contains aircraft and interface conguration data to match the
installation. Any future avionic upgrades on equipment interfaced to the
autopilot may require a new conguration le to be uploaded.
1.6.2. Aircraft Conguration
The aircraft conguration contains specic gains and servo drive values
to match the aircraft ight characteristics. Gain values are specically
setup during STC ight testing and are calculated for the optimum ight
performance of each aircraft model/type.

Section 1 Overview
1-52nd Ed Aug 2019 S-TEC 3100 Digital and Analog
1.6.3. Interface Conguration
The S-TEC 3100 has been designed to interface to both modern digital EFIS
systems and older analog navigation and heading systems. The interface
conguration ensures the 3100 maximizes performance by utilizing any
available data from both digital and analog sources.
1.6.4. Servo Assemblies
The S-TEC 3100 servos are used to move the aircraft
control surfaces. They are driven by the FGC using
pulse width modulated (PWM) signal. The pulse width
modulation allows the FGC greater control over the
speed of servo during uctuations in aircraft voltage.
Figure 1-3: S-TEC 3100 Servos
1.6.5. Sandia Air Data Computer
The Sandia SAC7-35 is installed on non-EFIS
installations that do not have a digital source of air
data. The ADC provides essential airspeed and
altitude data required for the 3100 internal attitude
source to calculate attitude angles and rates.
Figure 1-4: Sandia SAC7-35
1.6.6. GPS 1/2 Selector Switch
Some installations with dual GPS navigators may have a GPS 1/2 selector
switch located in the panel with an associated LED. Position of the switch
determines from which GPS source the 3100 is receiving navigation data.
1) With the LED extinguished the 3100 is following to GPS/NAV 1
2) With the LED illuminated the 3100 is following to GPS/NAV 2
If there is no GPS 1/2 selector switch installed, the 3100 is automatically
switched by the interfacing EFIS or only a single GPS navigation source is
available.

Section 1 Overview
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
1-6
NOTE:
The autopilot always follows the source selected by the GPS 1/2
selector switch regardless of the source displayed on the PFD. Always
ensure the GPS 1/2 selector switch position matches the navigation
source displayed on the PFD.
1.7. INTERFACED AVIONICS
The S-TEC 3100 may be setup to integrate with both analog and digital
systems, which includes (but not limited to) the following.
1.7.1. Garmin G500/G600/TXi EFIS
All mode annunciation is displayed on the 3100 bezel, but the G500/600/
TXi does not display 3100 AFCS mode annunciations.
Altitude pre-select is available and the 3100 reads VS, IAS and ALT targets
set on the EFIS display (§ 3.8.5).
If a target is set using the 3100 bezel directly, this supersedes any existing
targets from the EFIS and the new target is displayed as the altitude
annunciation.
Flight director command bars are displayed on the EFIS.
NOTE:
The G500/600/TXi does not update the EFIS displayed targets set on
the 3100 bezel directly.
1.7.2. Aspen EFD 500/1000/MAX
All mode annunciations are displayed on the 3100 bezel, but the EFD1000
does not display 3100 AFCS mode annunciations.
Indicated airspeed data is not provided from the Aspen EFD1000. Therefore,
some installations may not have IAS mode or envelope protection unless
supplemented with additional air data equipment.
This interface uses the 3100 internal altitude pre-select. VS, IAS, and ALT
targets cannot be set using the PFD bugs (§ 3.8.5).

Section 1 Overview
1-72nd Ed Aug 2019 S-TEC 3100 Digital and Analog
For dual GPS navigators, a GPS 1/2 selector switch is required. See § 1.6.6
for function details.
Flight director interface box (ST-670/ST-645) required to display ight
director command bars on the EFIS.
1.7.3. Avidyne EXP5000 and Meggitt EFIS
All mode annunciations are displayed on the 3100 bezel, but the EFIS does
not display 3100 AFCS mode annunciations.
This interface uses the 3100 internal altitude pre-select. VS, IAS, and ALT
targets cannot be set using the PFD bug (§ 3.8.5).
For dual GPS navigators, a GPS 1/2 selector switch is required. See § 1.6.6
for function details.
Flight director command bars are displayed on the EFIS.
1.7.4. Analog DG/HSI
All mode annunciations are displayed on the 3100 bezel. Providing baro-
correction to the 3100 enables the 3100 internal altitude pre-select (§ 3.8.5).
This interface is also compatible with the S-TEC ST-360 altitude selector/
alerter (§ 3.8.5).
For dual GPS navigators a GPS 1/2 selector switch is required. See § 1.6.6
for function details.
External ight director indicator required to display ight director command
bars.
NOTE:
Installations that do not provide baro-corrected data or have an ST-
360 installed do not have altitude pre-select and will need to perform a
manual altitude capture for climbs and descents (§ 3.8.5.1).

Section 1 Overview
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
1-8
1.8. DISPLAY LEGEND
Figure 1-5: Display Legend
1) Autopilot (AP) Mode button
2) Flight Director (FD) Mode button
3) Yaw Damper (YD) Mode button (Optional) - (See Figure 1-1)
4) Heading (HDG) Mode button
5) Navigation (NAV) Mode button
6) Approach (APR) Mode button
7) Level (LVL) Mode button
8) Ambient light sensor
9) Indicated Airspeed (IAS) Mode button
10) Vertical Speed (VS) Mode button
11) Altitude Hold (ALT HOLD) Mode button
12) Menu (MNU) Mode button
13) Altitude Selector (SELECT) knobs
14) Up/Down (UP/DN) Modier switch
15) Altitude Selector/Alerter annunciation
16) Engaged Pitch Mode annunciation
17) Armed Pitch Mode annunciation
18) Engaged Roll Mode annunciation
19) Armed Roll Mode annunciation
20) Light Emitting Diodes (LEDs)

Section 2 Pre-Flight Procedures
2-12nd Ed Aug 2019 S-TEC 3100 Digital and Analog
Section 2 Pre-Flight Procedures
2.1. POWER-UP TEST
Perform the following actions during power-up.
1) Set battery master switch to ON position.
2) Set avionics master switch to ON position.
3) Set AP master switch to ON position.
4) Set trim master to ON position.
NOTE:
For proper manual electric trim function, both the AP master switch and
trim master switch must be on during the 3100 self-test.
CAUTION:
DO NOT taxi until initialization is complete, and AP READY is
displayed. Taxiing during the initialization process may result in a
long initialization time.
The following occur in sequence:
ADAHRS INITIALIZING appears upon
power-up to initialize the system and
align the internal attitude sensor.
Self Test In Progress appears during
3100 self-test of the following:
1) Memory and processor tests
2) Interface tests
3) Servo driver tests
AP READY indicates 3100 is ready for
operation.

Section 2 Pre-Flight Procedures
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
2-2
The 3100 cannot be engaged if any of the following failure annunciations
are displayed.
If the on-board attitude sensor fails to
align, ATTITUDE FAIL appears.
If initial alignment is not valid after
congured start-up time or data
becomes invalid following the alignment,
AP FAIL appears.
2.2. PRE-FLIGHT CHECKS
Preight checks are detailed in the Aircraft Flight Manual Supplement
(AFMS) and should be carried out before every ight. Any failures or
unexpected behavior must be rectied before ight.

Section 3 In-Flight Procedures
3-12nd Ed Aug 2019 S-TEC 3100 Digital and Analog
Section 3 In-Flight Procedures
3.1. ENGAGING THE AUTOPILOT
3.1.1. Roll Attitude (ROLL) Mode
With the 3100 in AP READY state, press to engage AP, FD, and YD
(if applicable) simultaneously, as indicated by illuminated LED.
AP ON • Pitch/Roll servos are engaged
• Envelope protection is active
FD ON • Pitch/Roll servos are disengaged
• Drives ight director bars (if applicable)
• Envelope protection is passive
YD ON • Yaw servo is engaged
Figure 3-1: Roll Attitude (ROLL) Mode
During normal operation:
1) Pressing always engages FD simultaneously
2) FD may be toggled ON/OFF
3) YD may be toggled ON/OFF independently
3.2. DISCONNECTING THE AUTOPILOT
The 3100 may be disconnected by any of the following means:
1) Press remote AP DISC/TRIM INTR switch located on the yoke; OR
a) First single press disconnects AP only, leaving FD engaged
b) Second single press subsequently disconnects FD
c) Hold AP DISC/TRIM INTR down for 1.25 seconds to disengage
both AP and FD and mute any annunciations.
2) Set AP master switch to OFF position; OR
3) Pull the AP circuit breaker; OR
4) Press when AP mode is engaged.

Section 3 In-Flight Procedures
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
3-2
NOTE:
The 3100 also disconnects under the following circumstances:
1) Push the manual electric trim switch;
2) When the 3100 detects a fault in the system or an attitude
miscompare.
3.3. AUTOPILOT (AP) OPERATION
The 3100 interprets the steering commands calculated by the ight director
and sends drive signals to the pitch and roll servos. The servos control the
connected aircraft ight surfaces to y the ight prole. The ight director
display provides a visual indication of how accurately the 3100 is tracking
the roll and pitch commands.
Active envelope protection is operating when the 3100 is in AP mode.
3.4. FLIGHT DIRECTOR (FD) OPERATION
The ight director (FD) calculates the vertical and lateral movement required
for the aircraft to follow the ight prole. The ight prole is determined by
the 3100 lateral and vertical mode selected and data from the interfaced
avionics.
In FD mode, the 3100 outputs pitch and roll steering commands for display
on a connected ight director display. The steering commands are present
whether a ight director display is connected or not. The FD provides a visual
indication of how accurately the pilot is tracking roll and pitch command.
Passive envelope protection is operating when the 3100 is in FD mode.
NOTE:
If the pilot does not track the steering cues when the 3100 is operating
in FD only mode, the ight director steering bars continue to increase
the pitch and roll to intercept the calculated ight prole at the time of
mode engagement.
It is recommended to sync up the aircraft attitude with the ight director
steering bars or select a new mode before engaging the 3100 to avoid
aggressive banks or climbs.

Section 3 In-Flight Procedures
3-32nd Ed Aug 2019 S-TEC 3100 Digital and Analog
NOTE:
When using FD mode on take-o󰀨, the 3100 should be in PITCH and
ROLL hold or Take-O󰀨-Go-Around (TOGA) modes.
3.5. YAW DAMPER (YD) OPERATION
NOTE:
Not applicable to aircraft without optional yaw damper installed.
YD mode may be engaged or disengaged at any time,
regardless of roll or pitch mode. When YD mode is engaged,
the yaw damper dampens any excessive adverse yaw and
coordinates turns.
Figure 3-2: Without Optional Yaw Damper Installed
CAUTION:
YD mode should always be disengaged prior to takeo󰀨 and landing.
3.6. ENVELOPE PROTECTION
The 3100 protects against underspeed, overspeed, and excessive bank
conditions using the envelope protection feature. The envelope speed
limits vary between airframes depending on stall speeds, VNE, and whether
the aircraft is approved for ight-into-known-icing (FIKI). Specic limits are
stated within the relevant AFMS.
NOTE:
Underspeed and overspeed protection requires IAS data and are not
operational on installations without IAS mode available.

Section 3 In-Flight Procedures
2nd Ed Aug 2019
S-TEC 3100 Digital and Analog
3-4
3.6.1. Envelope Speeds for FIKI Aircraft
FIKI aircraft may have two di󰀨erent underspeed protection limits if the prop
de-ice system power has been tied to the 3100. With the de-icing system
activated the underspeed limit increases to match the increase in stall
speed value for ying in icing conditions.
A remotely mounted LED in the aircraft panel labeled “AP ICE SPEED”
illuminates when the higher underspeed limit is in e󰀨ect.
3.6.2. Passive Envelope Protection
Passive envelope protection is operating anytime FD mode is engaged,
indicated by the FD LED being illuminated.
1) Underspeed alert activates if the aircraft speed reaches the low speed
limit, which triggers an audible alarm followed by an “Airspeed,Airspeed”
voice alert. Alerts continue until the aircraft speed is increased beyond
the underspeed recovery limit as stated in the AFMS
2) Overspeed alert activates if the aircraft speed reaches the high speed
limit, which triggers an audible alarm followed by an “Overspeed,
Overspeed” voice alert. Alerts continue until the aircraft speed is
reduced below the overspeed recovery limit as stated in the AFMS.
3) Excessive Bank alert activates if the aircrafts roll attitude exceeds
60 degrees, which triggers an audible alarm followed by an “Attitude,
Attitude” voice alert. Alerts continue until the aircraft roll attitude is
reduced below 60 degrees.
3.6.2.1. Passive Envelope Protection on Approach
The overspeed and underspeed audible alarms and visual alerts are
disabled when the 3100 is in any of the approach modes (APRLOC, APRGPSS,
or APRGPSV) and the 3100 is in FD only (AP not engaged). This allows
pilots to hand y slower approaches but retain ight director command bar
guidance and to avoid nuisance speed callouts if AP is disconnected at
minimums but the FD remains engaged.
3.6.3. Active Envelope Protection
Active envelope protection is operating anytime AP mode is engaged,
indicated by the illuminated AP LED. Although excessive bank is still active,
it is not relevant while AP is engaged as the 3100 is already under control
of bank commands.