MIL-PRF-21480B
3.4 Design and construction. Components shall be constructed with parts and materials
designed to provide the specified performance, reliability, and service life under all
environmental and operating conditions specified herein. Electronic parts shall be de-rated to
enable components to provide the specified performance, reliability, and service life (see 6.5.3).
Static discharge control shall be provided for protection of electronic devices during assembly
and handling (see 6.5.2.4).
3.4.1 Electrical insulation and dielectric. Components shall withstand the high voltage
tests of 4.5.5 without discharge (surface or air) or electric insulation breakdown. Inspection shall
be in accordance with 4.5.5.1 for qualification and 4.5.5.2 for production lot conformance.
Component exposure to the electrical performance, endurance, and environmental tests required
by 4.5 of this specification shall not cause insulation breakdown or degradation.
3.4.2 Environmental performance. The generator package and all remote generator system
components shall conform to the requirements of this specification when subjected to
environmental conditions, as specified by the tests herein.
3.4.2.1 Temperature-altitude. The generator package and remote components shall
withstand the temperature-altitude conditions of the aircraft operating environment, as simulated
by the tests of 4.5.3, 4.5.14, and 4.5.28.
3.4.2.1.1 Blast air cooled and integral fan cooled components. Components that are blast
air cooled, or self-cooled by integral fan, shall meet the requirements of this specification when
subjected to the following conditions: (1) component compartment ambient conditions are within
the temperature-altitude limits on figure 1; (2) component cooling air temperature is within the
limits on figure 2; (3) cooling air flow and pressure are within specified limits of 3.4.9.6.1.b; and
(4) electrical load and shaft speed are within specified limits of 3.4.8, 3.4.9.1, and 3.5.3.
Operation with cooling air inlet temperatures above 85 °C shall be as specified in 3.4.9.6.1.
Unless otherwise required by the specification sheet, the altitude limit for continuous operation is
35,000 feet.
3.4.2.1.2 Liquid-cooled and self-cooled components. Components that are liquid cooled,
or self-cooled by convection, shall meet the requirements of this specification when subjected to
the following conditions: (1) component compartment ambient conditions are within the
temperature-altitude limits on figure 1; (2) liquid coolant supplied to components is within the
limits of 3.4.9.6.2; and (3) electrical load and shaft speed are within specified limits of 3.4.8,
3.4.9.1, and 3.5.3. Unless otherwise required by the specification sheet, the altitude limit for
continuous operation is 50,000 feet.
3.4.2.2 Humidity. System components shall withstand the humidity effects of operation
and storage, in tropical and maritime environments, as simulated by the test of 4.5.25.
3.4.2.3 Salt-spray. System components shall withstand the effects of operation and
storage, in maritime salt-spray and salt-fog environments when subjected to the test of 4.5.20.
Air cooled components shall withstand the effects of oil-saltwater ingestion from aircraft
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