DAC GDC31 Guide
Equipment Installation Manual,
GDC31 Roll Steering Converter
EQUIPMENT INSTALLATION MANUAL
For the
GDC31 ROLL STEERING CONVERTER
P/N 1049-4000-XX-001( )
REV G
DAC International
6702 McNeil Drive
Austin, TX 78729
©Copyright 2004, DAC International. All rights reserved.
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Equipment Installation Manual,
GDC31 Roll Steering Converter
RECORD OF REVISIONS
REV DESCRIPTION DATE APPROVED
IR INITIAL RELEASE E266 4-5-04 LW
A Correct P/N of mating connector E269 4/8/04 L Wootton
B CHANGED BREAKER TO 2 AMPS E272-04 4/19/04 LW
C Reduced 28V and 14V install kits into one
universal kit and added instructions for
configuration. Added wiring diagram for Bonanza
A-36. E306
7/26/04 LW
D Omit approval pending E321 9/17/04 LW
E Add numerous wiring diagrams E327 10/22/04 LW
F Add additional wiring diagrams, correct table 4
E389 3/30/05 LW
G Add lighting bus circuit diagram to all wiring
diagrams. Omit jumper on drawings Fig. 9 & 11.
Add note to installation section, page 16. E415
5/20/05 CC
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Table Of Contents
RECORD OF REVISIONS ...........................................................................................................................2
INTRODUCTION: ........................................................................................................................................5
DESCRIPTION:.............................................................................................................................................5
PART NUMBERS:........................................................................................................................................6
REGULATORY COMPLIANCE: ................................................................................................................6
Software .....................................................................................................................................................6
PMA...........................................................................................................................................................6
Environmental............................................................................................................................................6
SUPPLIED EQUIPMENT.............................................................................................................................7
OPTIONAL EQUIPMENT............................................................................................................................8
SPECIFICATIONS:.......................................................................................................................................9
Physical:.....................................................................................................................................................9
Electrical: ...................................................................................................................................................9
Serial Data Input: .....................................................................................................................................10
Roll Sum Steering Output:.......................................................................................................................10
ARINC 429 Output:.................................................................................................................................10
Reference Inputs: .....................................................................................................................................10
AP Offset Input:.......................................................................................................................................11
Annunciator Output: ................................................................................................................................11
Flag Input:................................................................................................................................................11
Certification: ............................................................................................................................................11
Reliability:................................................................................................................................................11
OPERATION:..............................................................................................................................................12
Overview..................................................................................................................................................12
Analog Output..........................................................................................................................................12
Reference Inputs (Excitation) .................................................................................................................12
ARINC 429 Output..................................................................................................................................12
GPS Mode Annunciator Control..............................................................................................................13
Super Flag Input.......................................................................................................................................13
INSTALLATION.........................................................................................................................................14
Material Not Supplied..............................................................................................................................14
Special Tools............................................................................................................................................14
Mounting Considerations.........................................................................................................................15
Wiring Considerations .............................................................................................................................15
Steering Output Scale Factor Determination...........................................................................................16
Configuration Pins ...................................................................................................................................17
Gain Setting Using Ref 1 input J1-18..................................................................................................17
Gain Settings Using Ref 2 input J1-6...................................................................................................17
Phase Selection ....................................................................................................................................18
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Position/Rate Selection ........................................................................................................................19
Baud Rate Selection.............................................................................................................................19
GPS Receiver Setup.............................................................................................................................19
REMOVAL AND REPLACEMENT..........................................................................................................20
Removal, GDC31.....................................................................................................................................20
Replacement, GDC31 ..............................................................................................................................20
Removal, Mode Annunciator...................................................................................................................20
Replacement, Mode Annunciator.............................................................................................................20
EQUIPMENT CHECKOUT........................................................................................................................21
Ground Functional Test ...........................................................................................................................21
Flight Functional Test..............................................................................................................................21
CONTINUED AIRWORTHINESS:............................................................................................................23
ENVIRONMENTAL:..................................................................................................................................24
CONNECTOR PIN OUT: ...........................................................................................................................25
OUTLINE DRAWINGS..............................................................................................................................26
GDC31 Outline ........................................................................................................................................26
Switch / Annunciator Outline ..................................................................................................................27
Isolation Coupler Outline.........................................................................................................................28
SLIDE LATCH ASSEMBLY......................................................................................................................29
APPENDIX A – AVIATION FORMAT.....................................................................................................30
APPENDIX B – 429 OUTPUT ...................................................................................................................31
Label 121 - Bank Angle Command .........................................................................................................31
Label 312 - Ground Speed .......................................................................................................................31
APPENDIX C - TYPICAL INTERCONNECT ..........................................................................................32
Figure 1 Typical Interconnect.................................................................................................................33
Figure 2 KI 525 / 525A with KA 52 / KA 57 ........................................................................................34
Figure 3 ARINC HSI with Century IV..................................................................................................35
Figure 4 ARINC HSI with S-TEC 50, 55 or 60.....................................................................................36
Figure 5 NSD 360A / NSD 1000 with Century IV................................................................................37
Figure 6 NSD 360A / NSD 1000 with S-TEC 50 or 55.........................................................................38
Figure 7 ARINC HSI with Century II or III ..........................................................................................39
Figure 8 KI 525A with KFC 150 ...........................................................................................................40
Figure 9 NSD 360 with ARC 400B (10VAC)......................................................................................41
Figure 10 52D54 DG with STEC 50, 55 or 60 ......................................................................................42
Figure 11 NSD 360 with ARC 400B (DC)............................................................................................43
Figure 12 NSD 360 with Century 2000 .................................................................................................44
Figure 13 NSD 360A with Century II or III ..........................................................................................45
Figure 14 HSI-70C with ARC 1000 .....................................................................................................46
Figure 15 KI 525A with KFC 200 / 300...............................................................................................47
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INTRODUCTION:
This Installation Manual contains installation data, specifications and Instructions for Continued
Airworthiness for the DAC International Model GDC31 Roll Steering Converter, Part Number 1049-
4000-XX-001( ).
DESCRIPTION:
The GDC31 Roll Steering Converter with software version 001( ) is designed to receive RS232 or RS422
serial data from a GPS Navigation System to produce both an analog Roll Sum Steering (RSS) signal and
ARINC 429 labels bank angle command and ground speed.
The GDC31 output signal connects to the heading error input of the aircraft’s existing autopilot. The
GDC31 mimics the heading error signal of the aircraft’s installed HSI or DG. The GDC31 does not
reduce or otherwise alter any existing safety features of the autopilot, such as bank limiting, rate limiting
and protection from a hard over. The GDC31 provides lateral (roll) data only (no pitch data is supplied by
the GDC31). The ARINC 429 output can drive digital autopilots or converters.
The pilot simply selects between heading mode and GPS mode using the supplied switch / annunciator.
In heading mode, the autopilot operates as always, tracking the heading bug of the HSI or DG. In GPS
mode, the GDC31 RSS signal drives the autopilot’s heading channel. The GDC31 calculates the correct
course intercept angle from the data supplied by the GPS, smoothly guiding the aircraft onto the course.
The GDC31 then holds the aircraft on the selected course. If the GPS is programmed with Flight Plan
data, the GDC31 will calculate the new intercept angle at each waypoint change, intercepting and holding
the new course without pilot intervention.
The GDC31 is designed to operate with both rate based and position based autopilots.
GDC31 RSC
SERIAL / FLAG
HDG
GPS
HSI / CDI
HDG ERROR
ROLL STEERING
HDG ERROR
ANNUN / SW
ARINC 429 OUT
GPS
AUTOPILOT
(GS, BANK ANGLE)
Block Diagram
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PART NUMBERS:
The GDC31 Data Converter is available under the following part numbers:
1049-4000-01-001( ) GDC31 Roll Steering Converter, ARINC 429 Low Speed
|
1049-4000-02-001( ) GDC31 Roll Steering Converter, ARINC 429 High Speed
|
Software part number, where ( ) contains the number zero for initial release, or
any letter, A – Z to denote a minor change.
REGULATORY COMPLIANCE:
Software
The Model GDC31 software was developed in accordance with RTCA/DO-178B to criticality level C.
PMA
The Model GDC31 is approved via PMA.
Environmental
The Model GDC31 meets the DO-160D environmental categories listed later in this manual.
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SUPPLIED EQUIPMENT
Each Data Converter is shipped with the following items:
Part Number Description Qty
1049-4000-01-001( ) GDC31 Roll Steering Converter, ARINC 429 Low Speed 1
1049-4200-10 Installation Kit, GDC31 Data Converter 1
Part Number Description Qty
1049-4000-02-001( ) GDC31 Roll Steering Converter, ARINC 429 High Speed 1
1049-4200-10 Installation Kit, GDC31 Data Converter 1
NOTE: The Annunciator / Switch, P10280, comes pre-configured for 28V operation. For 14V operation,
see the section titled INSTALLATION - Wiring Considerations.
Complete installation kits are available under kit part number 1049-4200-10. Individual pieces are
available under the part numbers shown. Contact DAC International sales to place orders.
Part Number Description Qty
1049-4200-10 Installation Kit, GDC31 Data Converter
M24308/2-3F Connector, Receptacle, 25 pin D-Sub 1
M39029/63-368 Socket, Crimp Style, female 25
P10219 Slide Latch Kit, shell size 3 1
P10220 Backshell, 25-Pin D-Sub 1
P10280 Mode Annunciator / Switch with 28V lamps 1
P10301 Lamp, 14V 4
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OPTIONAL EQUIPMENT
Certain installations require the use of an Isolation Coupler assembly. Refer to the applicable installation
drawings later in this manual for usage. This assembly is sold separately and comes with installation kit.
Part Number Description
1049-4801-01 Isolation Coupler
1049-4200-50 Installation Kit, Isolation Coupler
Complete installation kits are available separately under kit part number 1049-4200-50. Individual
pieces are available under the part numbers shown. Contact DAC International sales to place orders.
Part Number Description Qty
1049-4200-50 Installation Kit, Isolation Coupler
M24308/2-2F Connector, Receptacle, 15 pin D-Sub 1
M39029/63-368 Socket, Crimp Style, female 15
P10053 Slide Latch Kit 1
P10067 Backshell, 15-Pin D-Sub 1
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SPECIFICATIONS:
Physical:
The GDC31 attaches to the airframe via four mounting holes. See the paragraph titled GDC31 Outline
Drawing for further details.
RSC LRU
Height.................................................1.25”
Width..................................................5.22” (Includes mounting flange)
Depth..................................................3.54”
Weight................................................0.4 lb.
The Isolation Coupler (optional) attaches to the airframe via four mounting holes. See the paragraph
titled Isolation Coupler Outline Drawing for further details.
Height.................................................1.25 in
Width..................................................4.5 in (Includes mounting flange)
Depth..................................................2.41 in”
Weight................................................0.2 lb.
Annunciator
Height.................................................0.753”
Width..................................................0.753” (Includes mounting flange)
Depth..................................................1.99”
Weight................................................0.05 lb.
Electrical:
Input Voltage .....................................14 / 28 VDC (10Vdc – 32Vdc operational)
Input Current......................................0.1 Amp maximum at 28 VDC
Annunciator lamp current..................0.04 Amp at 28 VDC, 0.08 Amp at 14 VDC
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Serial Data Input:
Format................................................RS232 or RS422 serial data in RNAV 0, RNAV 1, King 0 or
King 1 format from a GPS navigation system
Baud Rate...........................................Selectable (2400, 4800, 9600, 19200)
Roll Sum Steering Output:
Description.........................................Analog bank angle command with program pin selectable scale
factors to match most autopilot input levels. Program pin
selection for position based or rate based output. Program pin
selectable phasing.
Load ...................................................1K
ARINC 429 Output:
Labels.................................................Bank Angle Command, Label 121
Ground Speed, Label 312
Baud Rate...........................................-01 Low Speed (12.5kBaud)
-02 High Speed (100 kBaud)
Reference Inputs:
General Description...........................AC or DC excitation used to excite the heading bug on the HSI
or DG. The GDC31 uses the reference input to produce a
steering signal with correct phase and amplitude characteristics.
Two reference inputs are provided. Use only one, depending on
the autopilot type. The unused input will be a no-connect. See
typical interconnect diagrams later in this manual.
AP Ref 1.............................................Reference voltage input for use with gain settings found in
Table 1.
Maximum Input Level ..................42 volts peak (30Vrms)
Load: ...........................................60K
AP Ref 2.............................................Reference voltage input for use with gain settings found in
Table 2.
Maximum Input Level ..................15 volts peak (10.6Vrms)
Load:............................................30K
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AP Offset Input:
Autopilot Offset.................................For autopilots that use a signal common that is not airframe
ground. Many use 5Vdc (relative to airframe) as the heading
bug signal common. In these cases, connect the autopilot signal
common to the GDC31 offset input pin, P1-19.
Maximum Input Level ..................7 volts peak (5Vrms)
Load:............................................10K
Annunciator Output:
GPS Coupled......................................Normally Open relay contacts configured as a SPST switch
intended to control an external GPS mode annunciator. The
GDC31 closes the contacts when the steering output is valid. It
cycles the contacts between open and closed at a 1 Hz rate if
steering data is invalid. Closed contacts connect pins P1-24 and
P1-12.
Max current:.......................................250mA
Flag Input:
Description.........................................Valid input to the GDC31 at J1-25, supplied from a GPS
receiver Super Flag output (14 or 28V).
Voltage:..............................................Greater than 6V is valid, less than 3V is invalid.
Load ...................................................200K ohms
Certification:
PMA
DO-178B............................................Level C
DO-160D............................................D1/BADSXXXXXXABBBAVB/A3E3/XXX
Reliability:
MTBF.................................................Greater than 50,000 hours.
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OPERATION:
Overview
The GDC31 Roll Steering Converter receives RS232 or RS422 serial data in RNAV 0, RNAV 1, King 0
or King 1 format from a GPS navigation system. It extracts Cross Track, Ground Speed and Track Angle
Error information from the data stream to compute an appropriate bank angle command to return the
aircraft to the Desired Track computed by the GPS navigation system.
Analog Output
The GDC31 produces an analog Roll Sum Steering (RSS) signal that drives the heading channel of the
autopilot. Phasing and amplitude of the RSS signal is based on the reference input supplied to the GDC31
from the autopilot and the gain and phase settings established by the program pins (refer to Tables 1, 2
and 3). The GDC31 will accept either an AC or a DC reference input as well as reference inputs that
contain an offset from airframe ground. The internal circuitry implements a multiplying Digital-to-
Analog converter that uses the external reference input to produce the desired signal output amplitude and
phase relative to the reference input. Certain installations (Century II and III, for example) will not accept
a heading error signal referenced to ground, so require the Isolation Coupler in order to transformer
isolate the GDC31 output signal.
Reference Inputs (Excitation)
The GDC31 contains two reference inputs to accommodate the wide range of reference voltages
available. Input Ref1 will accommodate excitation voltages up to a maximum input of 42 volts peak
(30Vrms). Input Ref2 will accommodate excitation voltages up to a maximum of 15 volts peak (15Vdc
or 10.6Vrms). The determination of which reference to use will depend on the gain needed to match the
autopilot scale factor as well as the maximum expected reference voltage. Certain installations (Century
II and III, for example) produce a reference voltage that is floating relative to airframe ground. These
installation require the Isolation Coupler in order to transformer isolate the GDC31 reference input signal.
ARINC 429 Output
The GDC31 produces an ARINC 429 digital output containing labels 121 and 312 intended to drive
digital autopilots or digital autopilot converters.
429 Label Output
(Octal) Description Rate
121 Bank Angle Command (BNR) 20 Hz
312 Ground Speed (BNR) 20 Hz
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GPS Mode Annunciator Control
The GDC31 contains a Normally Open relay contact configured as a SPST switch to control the external
GPS mode annunciator. This annunciator is further controlled by external switching and is active when
the pilot selects GPS mode in place of heading mode with the external switch. Refer to the typical
interconnect diagram later in this manual. If GDC31 output data is valid, the relay contacts are closed,
allowing the mode annunciator to illuminate. If the data is invalid, the GDC31 will cause the mode
annunciator to blink at a 1 Hz rate and command the steering output to zero degrees of bank (wings level).
The GPS mode annunciator blinks if either the super flag input is invalid or the serial data from the GPS
is missing or not the correct format (see Appendix A).
Super Flag Input
The GDC31 reads the Super Flag (14 or 28Vdc) from the GPS receiver. If the flag is greater than 5Vdc,
the flag shall be considered valid, if less than 2Vdc, the flag shall be considered as invalid. If the Super
Flag indicates invalid, the GDC31 shall produce a steering signal of zero degrees, blink the GPS
annunciator relay and invalidate the ARINC 429 label 121, bank command data, and label 312, ground
speed data.
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INSTALLATION
This section provides details for the installation of the GDC31 Roll Steering Converter, including
configuration, wiring, mounting and checkout procedures. Follow the procedures and recommendations
found in this section to assure a successful installation.
Read this entire section before beginning the installation.
Prior to installation, determine the required scale factor and phasing for use with the aircraft’s autopilot.
Consider the location of the mode selector / annunciator switch; it should be installed within the pilot’s
primary field of view and easily accessible by the pilot.
Complete an electrical load analysis in accordance with AC 43.13-1B, Chapter 11 prior to starting the
aircraft modification to insure the aircraft has sufficient load capability.
Complete an aircraft weight and balance prior to aircraft modification to insure the aircraft has sufficient
weight and CG margin.
Material Not Supplied
The following items are required for the installation but not supplied:
• Wire: MIL-W-22759/16 or equivalent
• Shielded Wire: MIL-C-27500 or equivalent
• Mounting screws: MS35206 6-32, 4 each
• Circuit Breaker: Klixon 7277-2-2 or equivalent
• Tie straps or lacing cord
• Ring terminals (for grounding)
• Splices
Special Tools
Use the following crimp tool to ensure reliable crimp contact connections to connector J1.
• Crimp tool M22520/2-01
• Positioner M22520/2-08
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Mounting Considerations
The GDC31 Roll Steering Converter can mount in the avionics bay, shelf or other suitable structure. It
can be mounted in any orientation.
The optional Isolation Coupler can mount in the avionics bay, shelf or other suitable structure. It can be
mounted in any orientation.
Attach the GDC31 and Isolation Coupler to suitable structure using the following hardware.
Screw, 8-32 X 1/2” MS35206-245
Flat Washer, #8 AN960-8L
Lock Washer, #8 MS35338-42
Nut, 8-32 MS35649-282
AN or MS self-locking nut plates may be used in place of the nut and lock washer specified above.
Mount the GPS/HDG mode annunciator / switch as near as practical to the autopilot mode controller. If
there is insufficient space there, mount the mode annunciator within the pilot’s primary field of view, near
the HSI or CDI.
Wiring Considerations
Wiring should be done in accordance with AC 43.13-1B, Chapter 11. Refer to the typical interconnect
diagram later in this manual for specifics. Use 22 to 24 AWG wire for all connections.
Fabricate wiring harness; refer to the interconnect diagrams and pin description. Test all the wiring for
continuity and for shorts. Insure aircraft power is on the correct pins of J1; refer to Table 6. Install slide
latch assembly onto J1 using instructions found later in this manual.
The mode annunciator/switch, P10280, comes pre-configured for 28V operation. For 14V operation,
perform the following steps:
1. Pull firmly on the edges of the lens to disengage the lamp assembly from the body. The lamp
assembly will hinge out and away from the body.
2. Remove and discard the four existing lamps, and replace with the four 14V lamps, P10301,
contained in the kit.
3. Push the lens firmly back into the body.
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NOTE:
Perform the following setup procedures in this section if a wiring diagram for a particular autopilot is not
included in this manual.
Steering Output Scale Factor Determination
The GDC31 is designed to mimic the heading error signal produced by the existing HSI or DG, so it can
operate with the wide variety of autopilots in current use. These various autopilots employ a wide range
of reference voltages and scale factors to interface with the array of HSI and DG control heads.
Reference voltage, or excitation, is the autopilot signal used to excite the Heading Select bug in the HSI or
CDI. As used in this manual, scale factor refers to the autopilot’s response to the heading error input
signal, expressed in volts per degree of bank. Examples are 200mv/deg and 60mv/deg. Examples of
excitation voltage are 26Vac and 15Vdc. The GDC31 firsts computes the bank angle using data from the
GPS. It then uses the reference voltage along with the scale factor setting (gain setting) to produce a
signal that feeds into the autopilot’s heading error input to produce the desired bank angle.
The GDC31 has eight (8) choices for scale factor, selected with a combination of program pins (2 each)
and reference inputs (2 each). Tables 1 and 2 describe the program pin combinations for the various scale
factors. To determine the appropriate setting for a given autopilot, first determine the autopilot excitation
amplitude in volts (AC or DC). Next, determine the autopilot scale factor from the autopilot maintenance
data. The scale factor needs to be expressed as volts/degree of bank. Divide the scale factor by the
excitation (scale factor / excitation voltage). Then look in Tables 1 and 2 for the nearest Scaling value to
the one just computed.
If the gain is set too high, the commanded course intercept will be overly aggressive. For 90-degree
course changes, too much gain will often cause the aircraft to turn inside the new course then S-turn back
to capture the track.
If the gain is set too low, the commanded course intercept will be sluggish. For a 90-degree course
change, too little gain will often cause the aircraft to overshoot the desired course then S-turn back to
capture the track. Some autopilots limit the maximum bank angle to less than the 30 degrees, 22 degrees
for example. In these cases, the aircraft will exhibit the symptoms of too little gain because the aircraft
cannot turn sharp enough to capture the track without overshooting. Examine the attitude indicator during
a 90-degree course change to verify that the aircraft banks to 30 degrees, or in the case of rate based
autopilots, to a standard rate turn.
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Configuration Pins
The GDC31 produces one of four (4) different RSS output levels for each reference input. This scaling
selection is accomplished with program pins J1-10 and J1-22. Tables 1 and 2 define the scale factors
available for each of the reference inputs, Ref 1 and Ref 2
Gain Setting Using Ref 1 input J1-18
Scaling J1-10 J1-22
0.015138 Open Open (1)
0.011590 Open Ground (1)
0.007687 Ground Open (1)
0.003844 Ground Ground (1)
Table 1
RSS Output Scaling Selection for Ref 1 input
(1) For 14 volt aircraft, maximum AC output signal is limited to 6.3 Vrms (210mV per degree) or
8.9 Vdc (297mV per degree.
Gain Settings Using Ref 2 input J1-6
Scaling J1-10 J1-22
0.033444 Open Open (2)
0.025606 Open Ground (2)
0.016983 Ground Open (2)
0.008492 Ground Ground (2)
Table 2
RSS Output Scaling Selection for Ref 2 input
(2) For 14 volt aircraft, maximum AC output signal is limited to 6.3 Vrms (210mV per degree) or
8.9 Vdc (297mV per degree.)
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Phase Selection
The GDC31 will accommodate steering signals that are in phase with the reference or out of phase with
the reference. For DC heading error signals, in-phase means a positive error signal produces a right turn,
a negative error signal produces a left turn. Determine the correct phasing from the autopilot maintenance
data then wire P1-13 accordingly.
If the phasing is incorrectly wired, the autopilot will turn the opposite direction when coupled to the
GDC31 Roll Steering Converter.
Phase P1-13
IN Phase with Reference Open
OUT of Phase with Reference Ground
Table 3
Phase Selection
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Position/Rate Selection
The GDC31 is designed to operate with both position based and rate based autopilots. Configuration is set
by program pin P1-23.
Scaling J1-23
Position Based Open
Rate Based Ground
Table 4
Position / Rate Selection
Position based autopilots require attitude information from the attitude indicator or vertical gyro. Rate
based autopilots require turn rate information from the turn coordinator rate gyro. Determine the autopilot
type, if it is rate based then connect J1-23 to program pin common, J1-11.
Baud Rate Selection
The GDC31 will accept four (4) baud rates for GPS data configured using program pins P1-9 and P1-21.
Baud Rate P1-9 P1-21
9600 Open Open
2400 Open Ground
4800 Ground Open
19200 Ground Ground
Table 5
Serial Baud Rate Selection
Note: Use Program Pin Common, J1-11, as ground for all program pin connections
GPS Receiver Setup
Refer to the manufacturer's instructions for the GPS interfaced to the GDC31 RSC. Configure the GPS to
output the Aviation Format data described in Appendix A.
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REMOVAL AND REPLACEMENT
Removal, GDC31
1. Open the circuit breaker powering the GDC31.
2. Remove the connector by disengaging the slide latch then pulling the connector free.
3. Remove four (4) screws securing the unit to the airframe.
Replacement, GDC31
1. Open the circuit breaker powering the GDC31.
2. Attach the unit to the airframe with four (4) screws.
3. Seat the connector then engage the slide latch to secure.
4. Close circuit breaker.
5. Perform ground functional test found under Equipment Checkout in this manual.
Removal, Mode Annunciator
1. Open the circuit breaker powering the GDC31.
2. Pull firmly on the edges of the lens to disengage the lamp assembly from the body. The lamp
assembly will hinge out and away from the body.
3. Release the two (2) pawls by unscrewing the flat-head screws located inside the body.
4. Unplug the lamp module from the sleeve.
Replacement, Mode Annunciator
1. Open the circuit breaker powering the GDC31.
2. Plug the lamp module into the sleeve.
3. Secure by engaging the two (2) pawls to the sleeve.
4. Plug the lamp module into the body - it will snap into place.
5. Close the circuit breaker.
6. Perform ground functional test found under Equipment Checkout in this manual.
1049-2510-01 G.doc
1049-2510-01
Rev G Page 20 of 47
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