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HONEYWELL Aerospace Electronic Systems Page 52
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5.3 Mechanical Packaging
5.3.1 Unit Weight
The MARK III LRU maximum weight is twelve pounds.
5.3.2 Unit Size
The MARK III LRU is a 4-MCU box that meets the dimensional specifications in ARINC 600. The unit has
the following dimensions in inches:
Width* Height* Length (Maximum)
Length+Front Face
Projections
(Maximum)
MARK III 4.88 + .020 7.62 + .020 12.76 15.26
* Height and Width are for Unit Cover, the Front plate shall slightly exceed these dimensions.
5.3.3 Unit Connectors and Mounts
The MARK III provides a low insertion force, size 2, ARINC 600 rear connector shell assembly as defined in
ARINC 758 for standard interconnect. The connector is located on the center grid of the MARK III rear
panel.
The portable data loader connector that is contained on the unit’s front panel is a 53-pin circular connector
that as specified in ARINC 615 for standard interconnect. The PDL front panel connector that mates with
the LRU is connector type MS27473T-18A-53P.
The mounting tray which is used for installing the unit in an aircraft may be any commercially available
mount which is designed for the dimensional requirements in ARINC 600 for a 4-MCU unit. No special
requirements exist for this mount.
5.3.4 Cooling Requirements
The MARK III is designed to accept cooling air using the method described in ARINC 600 or ARINC 404A.
The nominal cooling airflow requirement for the MARK III per ARINC 758 is 22.0 kilograms/hour of 40
degrees centigrade (maximum) air. The coolant air pressure drop through the MARK III should be 25 +2.5
millimeters of water.
If aircraft conditioned air is not available, the MARK III may be installed using an ARINC 600 equipment tray
that has an integral cooling an installed in the plenum.