Archangel AHR150A-1 User manual

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 1 of 26
AHR150A-1 I NSTALLATION M ANUAL
AHR150A Installation Manual Approvals:
Title and Name ignature and Date
Program Manager
Michael Greene
Michael Greene 18DEC2014
Director of Quality
Melissa Perdomo
Melissa Perdomo 18DEC2014
Company Confidential & Proprietary
No part of this publication may be reproduced in any form or
transmitted by any means without prior written permission from
Archangel Systems, Inc, Auburn, AL USA
Copyright © 014 by Archangel Systems, Inc.
All rights reserved.

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 2 of 26
AHR150A I M Change History Log:
Rev Description Date Author
IR Initial Release 17DEC 009 Michael Greene
A ADHR779 03MAR 011 K. Narayanan
B ADHR830 05FEB 013 V.Trent
C ADHR934 18DEC 014 B. Delaney

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 3 of 26
Table of Contents
1Introduction.................................................................................................... 5
1.1 Purpose ...............................................................................................................................5
1. Scope..................................................................................................................................5
2References ...................................................................................................... 5
.1 Regulatory Documents ..........................................................................................................5
. Archangel Systems Documents...............................................................................................5
3Overview......................................................................................................... 6
4Mechanical Installation ................................................................................... 7
4.1 ISU Installation ....................................................................................................................7
4.1.1 Orientation ....................................................................................................................8
4.1. Pitot Port Connection ....................................................................................................10
4.1.3 Static Port Connection ..................................................................................................10
5Electrical Installation .................................................................................... 11
5.1 ISU Wiring .........................................................................................................................11
5.1.1 Electrical Connections ...................................................................................................11
5.1. ISU Pin out Definitions for P Connector..........................................................................1
5.1.3 ISU Power Connections .................................................................................................14
5.1.4 Wire Sizing Recommendations .......................................................................................15
5.1.5 Bonding ......................................................................................................................15
5. Mating Connector................................................................................................................15
5.3 Strapping...........................................................................................................................15
5.3.1 Unit ID........................................................................................................................16
5.3. Orientation ..................................................................................................................16
5.3.3 Source Error and Lever Arm Corrections..........................................................................17
5.4 Discrete Heading Mode Inputs ..............................................................................................17
5.4.1 DG Mode (Unslaved Heading) Select...............................................................................17
5.4. CW Control..................................................................................................................18
5.4.3 CCW Control................................................................................................................18
5.4.4 AHR150A- MSU Failure................................................................................................18
5.5 Discrete Output ..................................................................................................................19
5.5.1 Discrete Fault Output (DFO) ..........................................................................................19
5.5. Transponder Port .........................................................................................................19
6Notes ............................................................................................................ 20
6.1 Alphabetical Listing of Acronyms and Abbreviations................................................................. 0
7Appendix A.................................................................................................... 21
7.1 Application Note on Multiple Unit Installations ........................................................................ 1
7.1.1 Introduction ................................................................................................................ 1
7.1. Laboratory Testing ....................................................................................................... 1
7.1.3 Results ....................................................................................................................... 3
7.1.4 Discussion ................................................................................................................... 5
7.1.5 Conclusions ................................................................................................................. 6

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 4 of 26
Table of Tables
Table 1: Allowed ISU Orientations..........................................................................................8
Table : ISU Pin out Definitions for P Connector................................................................... 14
Table 3: AHR150A-1 Power Specifications ............................................................................. 14
Table 4: AHR150A Cable Specifications................................................................................. 15
Table 5: Unit ID bit definitions ............................................................................................. 16
Table of Figures
Figure 1: AHR150A-1 Inertial Sensing Unit (ISU) ..................................................................... 6
Figure : AHR150A-1 ISU Mounting Holes and Alignment Patterns ............................................. 8
Figure 3: ISU Orientation Definitions (Shown in +X, +Z) .......................................................... 9
Figure 4: ISU Installation in the Avionics Bay of a BA609 (Orientation 0000)............................... 9
Figure 5: Power Wiring Diagram .......................................................................................... 14
Figure 6: DG Mode Switching .............................................................................................. 17
Figure 7: Adjusting Heading in DG Mode ............................................................................... 18
Figure 8: DFO Wiring.......................................................................................................... 19
Figure 9: Test Setup...........................................................................................................
Figure 10: Inertial Roll Angle Results.................................................................................... 3
Figure 11: Inertial Pitch Angle Results .................................................................................. 4
Figure 1 : Back to Back Mounts........................................................................................... 5
Figure 13: Side by Side Mounts ........................................................................................... 6

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 5 of 26
1Introduction
1.1 Purpose
This Installation Manual (ISM) details the installation procedures and requirements for the
AHR150A-1 Inertial Sensing Unit (ISU). This document is applicable to all Air Data Attitude
Heading Reference systems (ADAHRS) in the AHR150A family including the AHR300A.
1.2 Scope
The target audience of this document is any party installing an AHR150A-1.
2References
The following is a list of standards, procedures, and documents associated with this
document.
2.1 Regulatory Documents
The following regulatory documents provide supporting information to the contents of this
Installation Manual.
T O AE tandard Title & upplier
C4c AS396, AS8001 SAE International, 400 Commonwealth Dr. Warrendale, PA
C e AS8021 SAE International, 400 Commonwealth Dr. Warrendale, PA
C6d AS8013, Rev. A SAE International, 400 Commonwealth Dr. Warrendale, PA
C88b AS8003 SAE International, 400 Commonwealth Dr. Warrendale, PA
C106 AS8002, Rev. A SAE International, 400 Commonwealth Dr. Warrendale, PA
2.2 Archangel Systems Documents
Further details of installation, details of operation and data formats can be found in the
Interface Control Document (ICD) listed below.
Document Number Title
ICD-AHR1 0A Interface Control Document for AHR1 0A
SRS-AHR1 0A System Requirements Specification for the AHR1 0A and AHR300A

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
Page 6 of 26
3Overvie
The AHR150A family of ADAHRS are all composed of boxes: an ISU (AHR150A-1)
containing inertial and air data sensors, power conditioning, processors and ARINC 4 9
communication ports, and an MSU (AHR150A- ) containing a 3 axis magnetometer and
processor for magnetic field measurements. The MSU receives power from the ISU and is
only connected to the ISU electrically.
The Inertial Sensing Unit (ISU) can be seen in Figure 1 with its key components identified:
The AN6 Static Pressure Port, AN4 Pitot Pressure Port, six pin Maintenance port connector
with lanyard, 100 pin main connector for power and data and the four mounting feet.
Figure 1: AHR150A-1 Inertial ensing Unit (I U)
Static Port
Pitot Port
Maintenance Port
Mounting Feet (4)
Main Power and
Data Connector

Installation Manual
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Release Date: 18DEC 014
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4Mechanical Installation
Further details of installation and details of operation can be found in the Interface Control
Document (ICD) listed in the reference section above.
Note: For Software Versions 1.11 and later, refer to the Ground Maintenance Tool Manual
for additional setup and configuration instructions.
4.1 ISU Installation
The ISU is not approved for installation outside the aircraft. It can be installed either inside
or outside the pressure vessel in unheated and uncooled areas. The AHR150A-1 is
intended to be installed in the nose or avionics bay of the aircraft. If the AHR150A-1 is
installed in an area where the vibration profile exceeds the qualification profiles, the unit
may not function as intended.
The ISU is attached to the airframe using 4 #10-3 socket head screws in the pattern
shown in Figure , torqued to 31.7 inch-lbs. Also shown in this figure are the alignment
fiducials which are the 0. 5” hole and oblong hole (Detail A)used to ensure that the ISU is
aligned with the aircraft axes.
Because the AHR150A-1 is a strapdown measuring system, any errors in alignment from
the longitudinal axis of the unit to the longitudinal axis of the airframe will contribute to
errors in the outputs of the unit. The AHR150A-1 must be installed in the aircraft such that
the roll axis of the AHR150A-1 box is within ±0. 5° of parallel alignment with the aircraft’s
longitudinal axis.
For multiple system installations, all systems must be installed within ±0. 5° of parallel
alignment with each other. Failure to do so will likely cause reported miscompares from
displays.

Installation Manual
Document Number: ISM-AHR150A-1
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Release Date: 18DEC 014
Document Author: Project Manager
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Figure 2: AHR150A-1 I U Mounting Holes and Alignment Patterns
4.1.1 Orientation
The ISU can be installed in a variety of orientations. The connector side (CS) and the feet
side (FS) can be oriented along the positive and negative directions of the principal axes of
the aircraft as defined by Table 1 and Figure 3. The 0010 orientation is shown in Figure 3.
Orientation bits
(3-0)
Connector ide
(Axis)
Feet ide
(Axis)
0000 Aft(-X) Down(+Z)
0001 Right(+Y) Down(+Z)
0010 Forward(+X) Down(+Z)
0011 Left(-Y) Down(+Z)
0100 Forward(+X) Up(-Z)
0101 Left(-Y) Up(-Z)
0110 Aft(-X) Up(-Z)
0111 Right(+Y) Up(-Z)
Table 1: Allowed I U Orientations

Installation Manual
Document Number: ISM-AHR150A-1
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Release Date: 18DEC 014
Document Author: Project Manager
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Figure 3: I U Orientation Definitions ( hown in +X, +Z)
For the installation shown in Figure 4, the orientation is 0000 (Connector Aft(-X), Feet
Down(+Z)).
Figure 4: I U Installation in the Avionics Bay of a BA609 (Orientation 0000)
+
Z
AHR150A
-
1
+X (Direction of
+
P
P1
Feet
Side
(FS)
Connector
Side
(CS)

Installation Manual
Document Number: ISM-AHR150A-1
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4.1.2 Pitot Port Connection
The AHR150A-1 has a single Pitot Pressure port consisting of an AN4 Male connector. The
thread used for the AN4 connector is MS33656-4 (7/16- 0 male thread for 1/4” tubing).
During a pressurization test on the ground, the hull pressure is raised to 75 K Pa (-15,000
feet). This pressure will destro the Pitot Pressure sensor if it is vented to the cabin. This
port must remain vented to the atmosphere during such tests.
During decompression testing, this port must remain vented to the atmosphere.
4.1.3 Static Port Connection
The AHR150A-1 has a single Static Atmospheric Pressure port consisting of an AN6 Male
connector. The thread used for the AN6 connector is ms33656-6 (9⁄16-18 male thread for
3/8’’ tubing).
During a pressurization test on the ground, the hull pressure is raised to 75 K Pa (-15,000
feet). This pressure will destro the Static Atmosphere Pressure sensor if it is vented to the
cabin. This port must remain vented to the atmosphere during such tests.
During decompression testing, this port must remain vented to the atmosphere.

Installation Manual
Document Number: ISM-AHR150A-1
Revision: C
Release Date: 18DEC 014
Document Author: Project Manager
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5Electrical Installation
Note: For Software Versions 1.11 and later, refer to the Ground Maintenance Tool Manual
for additional setup and configuration instructions.
5.1 ISU Wiring
5.1.1 Electrical Connections
The electrical connections to the AHR150A-1 are on one circular Mil-C-38999 3-35 filtered
connector for normal operations. This connector is designated P and the pin outs for the
P connector can be found in ISU Pin out Definitions for P Connector .
This connector has the following signals available:
1. Four Hi Speed ARINC 4 9 transmit ports
. Four Lo Speed ARINC 4 9 transmit ports
3. One Hi Speed ARINC 4 9 receive port
4. One Lo Speed ARINC 4 9 receive port
5. One RS 4 Port for MSU communications
6. Isolated power for the MSU (9 VDC)
7. ICAO digital pressure altitude (isolated)
8. Two Power pairs, redundant and diode isolated
9. Outside air temperature (OAT)
10. Discrete output lines (isolated Fault and ICAO Transponder outputs)
11. Discrete input lines (isolated)
a. Parity strapping
b. Orientation strapping
c. PSEC/SSEC strapping
d. Unit ID strapping
e. DG mode Select
f. Slew CC
g. Slew CCW
1 . Return lines (provided for user grounds and strapping)

Installation Manual
Document Number: ISM-AHR150A-1
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Release Date: 18DEC 014
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5.1.2 ISU Pin out Definitions for P2 Connector
P2 P2
Pin ignal Pin ignal
1 ARINC 429 Port 1 Transmit, A1, Hi
Speed 1 Reserved
2 ARINC 429 Port 2 Transmit, A2, Hi
Speed 2 Reserved
3 ARINC 429 Port 3 Transmit, A3, Hi
Speed 3 Parity 0
4 ARINC 429 Port 4 Transmit, A4, Hi
Speed 4 Parity 1
ARINC 429 Port Transmit, A , Lo
Speed
Parity 2
6 ARINC 429 Port 6 Transmit, A6, Lo
Speed
6 No Pin
7 ARINC 429 Port 7 Transmit, A7, Lo
Speed
7 Power Input Primary
8 ARINC 429 Port 1 Transmit, B1, Hi
Speed
8 No Pin
9 ARINC 429 Port 2 Transmit, B2, Hi
Speed
9 No Pin
10 ARINC 429 Port 3 Transmit, B3, Hi
Speed
60 MSU Power Positive (AHR1 0A-2)
11 ARINC 429 Port 4 Transmit, B4, Hi
Speed
61 Reserved
12 ARINC 429 Port Transmit, B , Lo
Speed
62 Reserved
13 ARINC 429 Port 6 Transmit, B6, Lo
Speed
63 PSEC1
14 ARINC 429 Port 7 Transmit, B7, Lo
Speed
64 PSEC2
1 ARINC 429 Port 8 Transmit, A8, Lo
Speed
6 SSEC1
16 ARINC 429 Port 1 Receive, A1, Hi Speed 66 SSEC2
17 ARINC 429 Port 1 Receive, B1, Hi Speed 67 No Pin
18 Common Signal Return Isolated from
Case
68 Power Input Secondary
19 Common Signal Return Isolated from
Case
69 No Pin

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P2 P2
Pin ignal Pin ignal
20 Common Signal Return Isolated from
Case
70 No Pin
21 Common Signal Return Isolated from
Case
71 ICAO Signal Return, Isolated from all other
Returns and Case
22 ARINC 429 Port 8 Transmit, B8, Lo
Speed
72 Reserved
23 MSU RS422 Port Receive A, Positive 73 Outside Air Temperature , Positive
24 MSU RS422 Port Receive B, Negative 74 AOA Sensor, Positive
2 ARINC 429 Port Receive, A , Lo Speed 7 Heading Mode Select
26 ARINC 429 Port Receive, B , Lo Speed 76 CW
27 Common Signal Return Isolated from
Case
77 No Pin
28 Common Signal Return Isolated from
Case
78 Power Negative, Isolated from Case
29 Common Signal Return Isolated from
Case
79 No Pin
30 Common Signal Return Isolated from
Case
80 No Pin
31 Common Signal Return Isolated from
Case
81 MSU Power Negative (AHR1 0A-2)
32 Common Signal Return Isolated from
Case
82 AHR1 0A-1 Discrete Fault Line
33 MSU RS422 Port Transmit A, Positive 83 AOA Sensor, Negative
34 MSU RS422 Port Transmit B, Negative 84 Outside Air Temperature, Negative
3 Unit ID 0 8 CCW
36 Unit ID 1 86 No Pin
37 Common Signal Return Isolated from
Case
87 Power Negative, Isolated from Case
38 Common Signal Return Isolated from
Case
88 No Pin
39 Common Signal Return Isolated from
Case
89 No Pin
40 Common Signal Return Isolated from
Case
90 Digital Pressure Altitude B1
41 Common Signal Return Isolated from
Case
91 Digital Pressure Altitude A1
42 Reserved 92 Digital Pressure Altitude A4
43 Orientation Bit 0 93 Digital Pressure Altitude B4

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P2 P2
Pin ignal Pin ignal
44 Orientation Bit 1 94 Digital Pressure Altitude C2
4 Orientation Bit 2 9 Digital Pressure Altitude C4
46 Case Ground 96 Digital Pressure Altitude C1
47 Orientation Bit 3 97 Digital Pressure Altitude B2
48 Common Signal Return Isolated from
Case Ground
98 Digital Pressure Altitude D2
49 Nacelle Angle Selection 99 Digital Pressure Altitude A2
0 ICAO_EN 100 Digital Pressure Altitude D4
Table 2: I U Pin out Definitions for P2 Connector
5.1.3 ISU Power Connections
The power source for the AHR150A-1 is an isolated DC power supply using redundant input
power lines as specified in Table 3. Failure of either power line can be detected and
reported. Primary and secondary power should be run to separate buses to maintain
operation in the case one bus goes offline.
Description 28 VDC (Nominal Voltage)
Voltage Range 16 to 36 VDC
Current Less Than 1.1 A at 28 VDC
Less Than 2.2 A at 16 VDC
Table 3: AHR150A-1 Power pecifications
A A breaker is recommended for each power connection. Power Input and Power Negative
shall be run in a twisted shielded pair to common Avionics power and ground to maintain
EMI protection.
Figure 5: Power Wiring Diagram

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Release Date: 18DEC 014
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5.1.4 Wire Sizing ecommendations
The following are the recommended gauge wire sizes for the P mating connector.
ignal Name Wire Type
Power+, Power- 22 AWG twisted shielded pair
ARINC 429 22 to 26 AWG twisted shielded pair
ICAO Transponder 22 to 26 AWG in shield
Discrete 22 to 26 AWG in shield
Note: - Shields can terminate to strain relief of the connector which is electrically connected to the case of
the unit or to the case ground (pin 46).
Table 4: AHR150A Cable pecifications
5.1.5 Bonding
If the unit is mounted on an electrically conductive surface connected with the airframe, no
extra bonding requirement exists. If the unit is not mounted on a conductive surface,
connect the Case Ground (Pin 46) to an electrically conductive point on the airframe.
5.2 Mating Connector
The mating connector for P is Deutsch D38999/ 6WH35SN or equivalent.
5.3 Strapping
Note: For Software Versions 1.11 and later, refer to the Ground Maintenance Tool Manual
for setup and configuration instructions.
Strapping tells the ISU at power on
1. Its orientation
2. Its unit ID
3. What PSEC/SSEC tables to use
4. What lever arm corrections to use
There are 4 orientations, unit ID and 4 PSEC/SSEC strapping pins.
Strapping can be performed internally to the mating connector for P or carried out to a
terminal block in a shielded cable.

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It is important that all strapping lines and associated parity be configured correctly.
Incorrect orientation strapping will cause the ISU to report output angles,
angular rates and accelerations in the wrong coordinate system. For example, if
orientation bits were set to 0110 but the ISU was mounted with the feet down, a roll angle
of 180° would be outputted at boot up.
All parity must be odd for valid data. For example, if the unit is strapped as orientation
0, then the parity bit 1 must be a 1. In the example given, if the parity bit were set to 0,
all inertial data would be invalid from boot. Please refer to the ICD-AHR150A referenced
above for complete details on strapping. Incorrect Parity strapping will cause
invalidity of ARIN Data. Incorrect orientation parity strapping will cause ARIN
705 data to be invalid. Incorrect PSE /SSE parity strapping will cause ARIN
706 Data to be invalid. Incorrect unit ID strapping will cause all data to be
invalid.
5.3.1 Unit ID
The Unit ID bits 0 and 1 identify the units’ mounting location. The Unit ID definitions are
listed in Table 5.
Unit ID (1:0) Unit Name
00 Reserved
01 Unit 1(Left)
10 Unit 2(Right)
11 Unit 3(Third)
Table 5: Unit ID bit definitions
For example, to assign a Unit ID of (or 10 in the table above), the Unit ID 1 pin must be
connected to RTN and the Unit ID 0 pin must be left open. For Unit ID , Parity 0 must be
left open to achieve odd parity. For Unit ID 3 (11), Parity 0 must be strapped to RTN for
odd parity.
5.3.2 Orientation
The Orientation bits 0, 1, and 3 give sixteen possible orientations (only 8 are currently
available; see Table 1) for the AHR150A-1, when mounted on the aircraft. Figure 3 depicts
the relationship between the AHR150A-1 and the aircraft principal axes.
The connector side (CS) and the feet side (FS) can be oriented along the positive and
negative directions of the principal axes of the aircraft. The orientation bit definitions for
the different orientations are listed in Table 1.

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For example, to indicate an orientation of 0111, the Orientation Bit , Orientation Bit 1 and
Orientation Bit 0 pins must be connected to RTN and the Orientation Bit 3 pin must be left
open. For the orientation selection 0111, the Parity 1 pin must be left open to achieve a
valid odd parity. If the orientation selection is then rewired to 0011, the Parity 1 pin must
be connected to RTN to achieve a valid odd parity. For the installation of Figure 4, Parity 1
pin must be connected to RTN.
5.3.3 Source Error and Lever Arm Corrections
The ISU performs static source error correction and Pitot source error correction on the air
data, and PSEC1, PSEC , SSEC1 and SSEC bits form the strapping for the table to be
used. The ISU can use sixteen different tables, based on the strapping of these inputs.
Based on the same 4 source error correction straps plus unit ID, lever arm corrections are
applied to acceleration measurements. Therefore, with the same PSEC1, PSEC , SSEC1
and SSEC bits set, individual lever arm corrections are applied to up to 3 units (left, right,
other). Parity bit must be either left open (0) or strapped to RTN (1) to achieve odd
parity.
5.4 Discrete Heading Mode Inputs
5.4.1 DG Mode (Unslaved Heading) Select
This discrete input (pin 75) selects the operational mode for calculation of heading. An
open on this input will cause the ISU to slave heading to the MSU while connecting it to
RTN will select DG mode for heading computation. This can be done with a simple panel
mounted single pole switch such as a Honeywell 1TL1-3 (MIL – S – 3950).
Figure 6: DG Mode witching
DG Mode can also be activated by ARINC 4 9 commands. See ICD-AHR150A for details.
Pin 75
RTN
Case
DG Mode

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5.4.2 CW Control
Connecting the discrete input CW to RTN on this input will cause the output heading to
increase in a clockwise fashion at 1°/s increase to 5°/s after 5 seconds. This can be done
with a simple panel mounted momentary switch. A simple schematic is shown in Figure 7
with a CCW correction being applied.
CW rotation can also be activated by ARINC 4 9 commands. See ICD-AHR150A for details.
5.4.3 CCW Control
Connecting the discrete input CCW to RTN on this input will cause the output heading to
decrease in a counter clockwise fashion at 1°/s increase to 5°/s after 5 seconds. This can
be done with a simple panel mounted momentary switch. A simple schematic is shown in
Figure 7 with a CCW correction being applied. A typical switch that can be used is a
Honeywell 1TL1-7 (MIL – S – 3950).
Figure 7: Adjusting Heading in DG Mode
CCW rotation can also be activated by ARINC 4 9 commands. See ICD-AHR150A for
details.
5.4.4 AH 150A-2 MSU Failure
When a magnetometer (MSU) failure is detected, the AHR150A-1 automatically switches to
DG mode, irrespective of the DG mode switch setting. The magnetometer failure is relayed
in the output ARINC label 71 discrete bit 'MSU Fail', and the DG mode is indicated in the
discrete label 70. Auto-switch to DG mode due to magnetometer failure does not enable
slewing functions. If the AHR150A indicates an 'MSU Fail' and auto-switches to DG mode,
before attempting to slew the system CW/CCW, the user must explicitly activate DG mode
command using either the DG Mode discrete input or the ARINC label.
Pin 85
Pin 76
RTN
Case CW
CCW

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5.5 Discrete Output
5.5.1 Discrete Fault Output (DFO)
The ISU has a single Fault Line for reporting system status. This line will be pulled to RTN
under fault conditions and is capable of sinking 3.5 mA delivered from a 8 VDC source.
The DFO cannot support inductive loads. It is intended that a LED be connected from 8
VDC to the DFO. The LED would then light under Fault conditions and when no power is
applied to the ISU.
Figure 8: DFO Wiring
5.5.2 Transponder Port
Connecting the ICAO_EN to RTN enables the transponder port. This can be done in the
harness or at the transponder if it supports an enable line. The 11 transponder lines will
then be active and can be connected to the transponder inputs. Pull up resistors are
required but are usually part of the transponder. Should your installation appear to need
the pull up resistors, contact Archangel.
Fault
Case
Red LED
28

Installation Manual
Document Number: ISM-AHR150A-1
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Release Date: 18DEC 014
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6Notes
6.1 Alphabetical Listing of Acronyms and Abbreviations
Acronym Meaning
ARINC Aeronautical Radio Incorporated
ASI Archangel Systems Inc.
CCW Counter Clockwise
CS Connector Side
CW Clockwise
DFO Discrete Fault Output
DG Directional Gyro
ICD Interface Control Document
ISU Inertial Sensing Unit
MSU Magnetic Sensing Unit
OAT Outside Air Temperature
SRS System Requirements Specification
VDC Voltage D.C.