Midcontinent MD41 Series Technical Document

INSTALLATION MANUAL AND
OPERATING INSTRUCTIONS
MD41-( ) Series GPS ANNUNCIATION CONTROL UNIT
FOR II MORROW APOLLO 2001TSO / 2001GPS / 2101
GX50 /GX60
MD41-1728 28vdc Horizontal Mount
MD41-1738 28vdc Vertical Mount (shown on page 10)
MD41-1724 14vdc Horizontal Mount
MD41-1734 14vdc Vertical Mount (shown on page 10)
Mid-Continent Instruments and Avionics Manual Number 8013641
9400 E. 34th Street N., Wichita, KS 67226 USA REV. 0 Nov 12, 1998
Phone [phone] Fax [phone]

REV. 0 Nov. 12, 1997 2
TABLE OF CONTENTS
SECTION 1 GENERAL DESCRIPTION
1.1 INTRODUCTION
1.2 SPECIFICATIONS, TECHNICAL
1.2.1 PHYSICAL CHARACTERISTICS
1.2.2 ENVIRONMENTAL CHARACTERISTICS
1.2.3 SPECIFICATIONS, ELECTRICAL
1.2.4 FRONT PANEL CONTROLS AND ANNUNCIATIONS
1.2.4.1 CONTROLS
1.2.4.2 ANNUNCIATIONS
1.2.5 INTERFACE
1.2.6 EQUIPMENT LIMITATIONS
1.2.7 MAJOR COMPONENTS
SECTION 2 INSTALLATION CONSIDERATIONS
2.1 COOLING
2.2 EQUIPMENT LOCATION
2.3 ROUTING OF CABLES
SECTION 3 INSTALLATION PROCEDURE
3.1 GENERAL INFORMATION
3.2 UNPACKING AND INSPECTING
3.3 MOUNTING THE MD41-( )
3.4 INSTALLATION LIMITATIONS
SECTION 4 POST INSTALLATION CHECKOUT
4.1 PRE-INSTALLATION TEST
4.2 OPERATING INSTRUCTIONS
FIGURE N0. LIST OF ILLUSTRATIONS
3.1 SCHEMATIC PINOUT, 25 PIN DSUB
3.2 OUTLINE DRAWING
3.3 WIRING DIAGRAM, MD41-1724/1734 (14Volt),
MD41-1728/1738/1728(5V)/1738(5V) (28volt)
MD41-244/248
3.4 WIRING DIAGRAM, MD41-1700 SERIES ACU
AlliedSignal KI208A/209A INDICATOR
APPENDIX
ENVIRONMENTAL QUALIFICATION FORM

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SECTION 1 GENERAL DESCRIPTION
1.1 INTRODUCTION
The MD41-172X/173X is a compact, self -contained GPS Annunciation and Control unit.
It combines all the necessary functions required to interface the II Morrow Apollo
2001TSO / 2001GPS / 2101 /GX50 and GX60 approach-certified GPS receivers with the
MD41-244/248 remote mounted relay transfer system. In addition, the MD41-( ) contains
several GPS status annunciations used to indicate modes selected by the front panel
switches and various inputs from the GPS receiver.
A special ILS override feature has been incorporated to cause the MD41-( ) to
automatically switch to the NAV mode when the NAV (VOR) receiver is tuned to an ILS
frequency. Other features include dual 20,000 hour lamps used for all annunciations,
internally lighted selection switches and automatic photocell dimming. A external
annunciation dimming adjustment is provided for balancing low level light conditions.
The MD41-172X/173X series annunciation control unit must be installed with the
companion MD41-244/248 series Relay Unit or the AlliedSignal KI 208A/209A course
deviation indicator to be approved as a complete TSO’d system.
1.2 SPECIFICATIONS, TECHNICAL
1.2.1 PHYSICAL CHARACTERISTICS
Mounting: Panel
Width: 3.25 Inches
Height: .80 Inches
Depth: 3.20 Inches
Weight: 0.50 lbs.
1.2.2 ENVIRONMENTAL CHARACTERISTICS
TSO Compliance: TSO C129
Applicable Documents: RTCA DO-160C, DO-208
Operating Temperature Range: -55C to +70C
Humidity: 95% Non-Condensing
Altitude Range: 0 to 55,000 ft.
Vibration: Cat. M and N
Operational Shock: Rigid Mounting, 6 G Operational
15GCrashSafety

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1.2.3 SPECIFICATIONS, ELECTRICAL
Design AllSolidState
MD41-1724/1734 (14VDC) 0.40 Amps
MD41-1728/1738 (28VDC) 0.30 Amps
MD41-1728(5V)/1738(5V) (28DC) 0.30 Amps
1.2.4 FRONT PANEL CONTROLS AND ANNUNCIATIONS
1.2.4.1 CONTROLS
NAV/GPS Alternate action switch, when pressed, will select
NAV (VOR) or GPS presentation on HSI/CDI.
GPS/SEQ Momentary action switch, when pressed, will select between
waypoint sequencing and waypoint hold mode.
In hold mode, this will enable OBS selection input from
the Apollo GPS system.
1.2.4.2 ANNUNCIATIONS
NAV NAV (VOR) information presented on the HSI or CDI.
GPS GPS information presented on the HSI or CDI.
MSG On indicates message(s) active.
PTK On indicates parallel track is enabled.
AUTO Automatic sequencing of waypoints is active.
OBS/HLD On indicates waypoint sequencing is in hold. Also OBS
Selection input from the Apollo GPS system
has been enabled.
APR On indicates the approach has been enabled.
ACTV On indicates the approach is active.
1.2.5 INTERFACE
NAV annunciation Receives a ground from the transfer relay
J1 Pin 2 when relays are in NAV mode.
GPS annunciation Receives ground from the transfer relay
J1 Pin 1 when relays are in GPS mode.

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1.2.5 INTERFACE (cont.)
Lamp Test Receives ground from remote rest switch
J1 Pin 7 to light all annunciations.
(optional connection)
GPS/SEQ Select Provides a momentary logic low to the
J1 Pin 10 GPS receiver when GPS/SEQ is selected.
OBS/HLD annunciation Receives a logic low to from the GPS receiver
J1 Pin 23 to annunciate OBS/HLD.
APR annunciation Receives a logic low from the GPS receiver
J1 Pin 4 when approach has been enabled.
ACTV annunciation Receives a logic low from the GPS receiver
J1 Pin 8 when a transition is made from APR to active.
PTK annunciation Receives a logic low from the GPS receiver
J1 Pin 9 to indicate parallel track is enabled.
ILS Override Receives a logic low from the NAV (VOR)
JI Pin 11 receiver when tuned to an ILS frequency.
This will force the MD41-( ) into NAV mode
regardless of the NAV/GPS selection. This
connection is optional.
MSG annunciation Receives a logic low from the GPS receiver
J1 Pin 3 to indicate message(s) is active.
FCS LOC ENGAGE Logic low when GPS is in ACTIVE mode.
J1 pin 11 Used to provide a ILS ground to the flight
control system when the GPS is approach
active.

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1.2.6 EQUIPMENT LIMITATIONS
The MD41-( ) series control units contain specific dash numbers to be used with various GPS
receivers. The installer must match the correct controller part number with the GPS receiver
being installed.
The conditions and tests required for TSO approval of this article are minimum
performance standards. It is the responsibility of those desiring to install this article either
on or within a specific type or class of aircraft to determine that the aircraft installation
conditions are within the TSO standards. The article may be installed only if further
evaluation by the applicant documents an acceptable installation and is approved by the
Administrator.
The MD41-1724/1734/1728/1738/1728(5V)/1738(5V) ACU MUST be installed with the
Mid-Continent Instruments and Avionics MD41-244/248 remote transfer relay or the
AlliedSignal KI 208A/209A course deviation indicator in order to be approved as a complete
TSO system. These items will not be TSO’d if one is installed without the other.
The MD41-1724/1734/1728/1738/1728(5V)/1738(5V) is TSO’D and certified for use with the
II Morrow Apollo 2001TSO / 2001GPS / 2101 / GX50 / GX60 system. Any attempts to install
the listed units in an installation other than the II Morrow Apollo 2001TSO / 2001GPS / 2101
/ GX50 / GX60 is prohibited. This will void the TSO.
NOTE: Anytime the MD41-( ) is disconnected or removed from the aircraft, the HSI/CDI
will default to NAV (VOR) mode.
1.2.7 MAJOR COMPONENTS
This system is comprised of two major components, the MD41-1700 series GPS Annunciation
Control Unit and the MD41-244/248 Remote Relay or the AlliedSignal KI 208A/209A course
deviation indicator.

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SECTION 2 INSTALLATION CONSIDERATIONS
2.1 COOLING
No direct cooling is required. As with any electronic equipment, overall reliability may be
increased if the MD41-( ) is not located near any high heat source or crowded next to other
equipment. Means of providing a gentle air flow will be a plus.
2.2 EQUIPMENT LOCATION
The MD41-( ) annunciation control unit must be mounted as close to the pilot’s field of view
as possible. The preferable location is near the HSI/CDI that will be displaying the GPS
information. The unit depth, with connector attached, must also be taken into consideration.
Note: Unlike previous versions of the MD41 Annunciation Control Units (ACU), the transfer
relays have been removed and are now remotely mounted in a separate package designated as
the MD41-244/248 Relay Unit. This has allowed a for a smaller size ACU which now
provides more options for panel mounting. For systems that utilize the AlliedSignal
KI208A/209A, the transfer relays are internal to the indicator.
2.3 ROUTING OF CABLES
Care must be taken not to bundle the MD41-( ) logic and low level signal lines with any high
energy sources. Examples of these sources include 400 HZ AC, Comm, DME, HF and
transponder transmitter coax. Always use shielded wire when shown on the installation print.
Avoid sharp bends in cabling and routing near aircraft control cables.

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SECTION 3 INSTALLATION PROCEDURES
3.1 GENERAL INFORMATION
This section contains interconnect diagrams, mounting dimensions and other information
pertaining to the installation of the MD41-( ). After installation of cabling and before
installation of the equipment, ensure that power is applied only to the pins specified in the
interconnect diagram.
3.2 UNPACKING AND INSPECTING EQUIPMENT
When unpacking equipment, make a visual inspection for evidence of damage incurred during
shipment. The following parts should be included:
1. MD41-1724 (14volt) or MD41-1728 (28 volt) Horiz. Mount
MD41-1734 (14volt) or MD41-1738 (28volt) Vert. Mount
MD41-1728(5V) (28volt) 5 volt button lighting Horiz. Mount
MD41-1738(5V) (28volt) 5 volt button lighting Vert. Mount
2. J1 Connector Kit (25 pin). MCI PN 7014517
3. Installation Manual. MCI PN 8013641
3.3 MOUNTING THE MD41-( )
Plan a location in the aircraft for the MD41-( ) to be mounted as close to the pilot’s field of
view as possible. The preferable location is near the HSI/CDI that will be displaying the GPS
information. Avoid mounting close to heater vents or other high heat sources. Allow a
clearance of at least 3 inches from back of unit for plug removal.
The indicator is secured in place behind the panel since it is designed for rear mount only.
Make a panel cutout as shown in Figure 3-2. Secure the indicator in place with two 4-40 x 3/8
flat head phillips screws.
3.4 INSTALLATION LIMITATIONS
Wire the aircraft harness according to figure 3-3. Use at least 24 AWG wire for all
connections. Avoid sharp bends and routing cable near high energy sources. Care must be
taken to tie the harness away from aircraft controls and cables. Normal installation techniques
should be applied. Also see equipment limitations, section 1.2.6.

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REAR VIEW OF J1 CONNECTOR
J1
PIN NO.
1 ---------------------------- GPS ANNUNCIATION (receives ground from remote transfer relays)
2 ---------------------------- NAV ANNUNCIATION (receives ground from remote transfer relays)
3 ---------------------------- MSG ANNUNCIATION (receives logic low from GPS receiver)
4 ---------------------------- APR ANNUNCIATION (receives logic low from GPS receiver)
5 ---------------------------- DIMMER IN (from aircraft dimming bus for push-button lighting)
6 ---------------------------- SPARE
7 ---------------------------- LAMP TEST (receives ground from remote test switch)(optional conn.)
8 ---------------------------- ACTV ANNUNCIATION (receives logic low from GPS receiver)
9 ---------------------------- PTK ANNUNCIATION (receives logic low from GPS receiver)
10 -------------------------- OBS MODE SELECT ( logic low sent to GPS receiver)
11 -------------------------- FCS LOC ENGAGE (ground when GPS is in active mode)(for autopilot)
12 -------------------------- TO NAV CIRCUIT BREAKER (for fault monitoring)
13 -------------------------- 14 or 28 VDC UNIT POWER (depends on dash number)
14 -------------------------- EXTERNAL RELAY ENERGIZE (ground to energize remote transfer
relays when GPS is selected)
15 -------------------------- SPARE
16 -------------------------- SPARE
17 -------------------------- SPARE
18 -------------------------- SPARE
19 -------------------------- SPARE
20 -------------------------- SPARE
21 -------------------------- SPARE
22 -------------------------- SPARE
23 -------------------------- OBS HOLD ANNUNCIATION (receives logic low from GPS_
24 -------------------------- SPARE
25 -------------------------- POWER GROUND
FIGURE 3-1 SCHEMATIC PINOUT, 25 PIN DSUB

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Note 1: Use two 4-40 X 3/8” Flat Head Phillips Screws for Mounting
FIGURE 3-2 OUTLINE DRAWING