scope:

Purpose and Use of this Specification

The purpose of this specification is to provide a system of modularized equipment dimensions plus methods of attachment to mating mounting for the use of avionic equipment designers. The racking system and its details have evolved over a number of years while acquiring increasing acceptance not just among the airline industry world-wide, but with the military as well. This document attempts to not limit the designer, but to guide him in the selection of the necessary attributes incidental to avionics box design providing him with airline industry preferred guidance. The designer does not have to follow the tenets in this 404A Spec, but he should realize the desirability of doing so and the chaos in the industry that would result if no such guideline were available.

In the ARINC Equipment Characteristic (See Section 1.4), the airline industry can be expected to provide direct guidance in the design of a specific equipment. The packaging details of such a device can be expected to be spelled out in detail or perhaps, as is more likely, the relevant sections of this document will be referenced.

Where no ARINC Equipment Characteristic document is involved, the material in 404A is provided as general, rather than direct, guidance on racking although the necessary alternatives of size, hold-down method, connector selection, and cooling construction should be selected on the basis of need by the designer.