MIL-PRF-21480B
operation in a maritime salt-spray environment. Components exposed to oil-saltwater ingestion
include: (1) blast-cooled generators; (2) self-cooled generators with integral fans; and (3) blast-
cooled heat exchangers used with liquid-cooled generators.
3.4.2.4 Fungus. System components shall be constructed of non-nutrient materials that do
not support the growth of fungus in aircraft operating environments (see 4.5.21).
3.4.2.5 Sand and dust. System components shall withstand the effects of sand and dust
particles from world-wide operation including desert and mountainous terrain, as simulated by
the sand and dust test of 4.5.22.
3.4.2.6 Mechanical shock (functional and crash safety). System components shall
withstand the effects of mechanical shock from handling, transport, and aircraft operations, as
simulated by the tests of 4.5.24 and the functional shock spectrum on figure 3. Components
shall remain in place and not create a safety hazard during a crash landing, as simulated by the
crash shock spectrum on figure 3.
3.4.2.7
Vibration.
3.4.2.7.1 Engine vibration (category 1). Components exposed to vibration from engines
and engine-driven gearboxes shall withstand the vibration spectrum on figure 4, when tested in
accordance with 4.5.23.2.1. Acceleration spectral density (g2/Hz) and vibration frequency (Hz)
values for the narrow band random spikes on figure 4 shall be as required by the specification
sheet (see 6.6.3.2).
3.4.2.7.2 Aircraft platform vibration. Non-engine mounted components shall withstand
the vibration environment of the applicable aircraft platform as specified herein (see 6.6.3.2).
a. Category 2 - Components mounted in jet aircraft shall withstand exposure to the
vibration spectrum on figure 5, when tested in accordance with 4.5.23.2.2.a.
b. Category 3 - Components mounted in propeller aircraft shall withstand exposure to the
vibration spectrum on figure 6, when tested in accordance with 4.5.23.2.2.b. Acceleration
spectral density (g2/Hz) and vibration frequency (Hz) values for the narrow band spikes on figure
6 shall be as required by the specification sheet.
c. Category 4 - Components mounted in helicopter rotary wing aircraft shall withstand
exposure to the vibration spectrum on figure 7A, when tested in accordance with 4.5.23.2.2.c.
Peak sine amplitude (g) and frequency (Hz) values for the sinusoidal spikes on figure 7A shall be
as required by the specification sheet.
3.4.2.8 Acceleration forces. System components shall withstand the inertial loads induced
by aircraft operation (acceleration, deceleration, and maneuvers) and provide specified
performance when subjected to the acceleration test of 4.5.35. Liquid-cooled generators shall
maintain specified performance (see 3.4.9.6.2) when exposed to aircraft operation inertial loads.
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