It is intended that ARINC 600 be used with the application andcustomer needs in mind. To enhance the breadth of use, thisdocument alludes to three phases defined as follows:
a. Phase I – This phase specifies the definitions, guidance, andappraisals given in Section 1.1 for those instances in which theaircraft manufacturer intends to randomly mix ARINC 600 boxes andARINC 404A boxes.
COMMENTARY
In some aircraft ARINC 600 boxes will be interspersed with ARINC404A boxes in one rack while others will be installed in adedicated ARINC 600 rack/cabinet. The guiding principle in thisSpecification is one-way generation interchangeability. ARINC 600Phase I boxes should meet qualification requirements and fit andperform satisfactorily when installed on a Phase 0 (ARINC 404A)rack. It is recognized that a portion of the ARINC 404A rack willhave to be made to accommodate the ARINC 600 Phase I boxes due todifferent hold-downs and different connectors. This is not to implythat cooling air will be different. Air will continue to be drawndown in ARINC 404A racks and ARINC 600 Phase I boxes will have tolive with this condition. On the other hand, an ARINC 404A boxcould not be installed in an ARINC 600 Phase I rack/cabinet becauseit may be too large, it has front “dog houses,” a cooling system(e.g., holes in the sides of the LRU) that would upset the coolingprovided in an ARINC 600 Phase I rack/cabinet, and for otherreasons. The user of this Specification may, therefore, alwaysinstall a mix of boxes in the lower numbered phase rack/cabinet andonly two phases will be mixed in one rack/cabinet.
b. Phase II – This phase was envisioned to specify thedefinitions, guidance, and appraisals for those instances whereARINC 600 boxes are of a design catering to mechanical, electrical,and environmental control that is substantially beyond thosefeatures for Phase I. Phase II, therefore, is another step in theevolutionary development of avionic installations. As with Phase Iand ARINC 404A, it is likely that aircraft manufacturers will findit necessary or convenient to sometimes mix Phase II and Phase Iboxes in a rack. When this is done, the installation criteria forPhase I will prevail. However, it would not be proper to installPhase II boxes in ARINC 404A shelves. The standard rule is toalways install a mix of boxes in the lower-numbered phaseshelf/cabinet and no more than two phases may be mixed on oneshelf. Put differently, a Phase N+1 box can be used in (and onlyin) a Phase N or a Phase N+1 rack/cabinet. Similarly, a Phase N boxcan be used only in a Phase N or Phase N-1 rack/cabinet.
COMMENTARY
The Commentary set forth in (a.) above applies. It must beclearly understood that Phase II has not been defined.
c. Phase III – This phase was envisioned to specify thedefinitions, guidance, and appraisals for those instances whereARINC 600 boxes are of a design catering to improved mechanical,electrical, and environmental control that is substantially beyondthose features for Phase II. The criteria for mixing Phase II andPhase III boxes include the requirement that such a mix must alwaysoccur in a Phase III rack/cabinet only.
COMMENTARY
The commentaries under (a.) and (b.) applies. It must be clearlyunderstood that Phase III has not been defined.
NIC Phase I Design Requirements are contained in Section 3 ofthis document.
- Edition:
- 10
- Published:
- 05/10/2010
- Number of Pages:
- 332
- File Size:
- 1 file , 6.9 MB
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