MIL-PRF-21480B
2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of
a conflict between the text of this document and the references cited herein (except for related
specification sheets), the text of this document takes precedence. Nothing in this document,
however, supersedes applicable laws and regulations unless a specific exemption has been
obtained.
3. REQUIREMENTS
3.1 Specification sheets. The individual item requirements shall be as specified herein and
in accordance with the applicable specification sheet. In the event of any conflict between the
requirements of this specification and the specification sheet, the latter shall govern.
3.2 Qualification. Generator systems furnished under this specification shall be products
that are authorized by the qualifying activity for listing on the applicable qualified products list
before contract award (see 4.2 and 6.3).
Materials.
3.3
3.3.1 Selection of materials, parts, and processes. Materials shall be used which enable the
generator system components to meet all of the operational and environmental performance
requirements of this specification and the applicable specification sheet (see 6.5.1 and 6.5.2).
Classification and inspection of castings shall be in accordance with SAE-AMS2175. Gearbox-
mounted components shall be class 1 or class 2, and all castings shall be classified as grade C or
higher in accordance with SAE-AMS2175.
3.3.2 Moisture resistance. Non-metal materials, including plastics, ceramics, fabrics, and
protective finishes, shall be moisture resistant. Non-metal materials and parts may be treated to
conform to this requirement. Electrical connectors shall be environment resistant as required to
withstand the environmental tests herein (4.5.20 through 4.5.28).
3.3.3 Corrosion resistance. All metals used in the generator system components
construction shall be processed and protected to resist corrosion (see 6.5.1.2). Protective
coatings and finishes shall provide abrasion resistance as required to withstand the environmental
tests specified herein. Magnesium alloy materials shall not be used in air cooled generators.
Dissimilar metals shall not contact each other unless protected against electrolytic corrosion in
accordance with MIL-STD-889. Corrosion protection applied to dissimilar metals, such as metal
plating and coatings, shall withstand the environmental tests specified herein.
3.3.4 Contamination by fluids. With the generator external surface temperature between
-40 °C and 150 °C, the generator package shall show no deterioration due to wetting from
aviation fluids, including fuel (JP-5/JP-8), fire extinguishing compounds, de-ice fluids, aircraft
washing fluids, hydraulic fluids, and lubricating oils (see 4.5.27 and 6.5.6).
3.3.5 Toxicity and fire resistance. Materials used shall be flame resistant, shall not support
combustion, and shall be non-toxic when exposed to flame in accordance with 4.5.33.
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