MIL-DTL-87223A (USAF)
random vibration background. The sinusoids shall be at frequencies representing the basic
gunfire rate f1 (100 Hz), and the second f2 (200 Hz), third f3 (300 Hz), and fourth f4 (400 Hz)
orders. Synchronously, the frequencies shall be swept logarithmically over a bandwidth equal
to ±0.2 f1, ±0.2 f2, ±0.2 f3, and ±0.2 f4 beginning at the low frequency end and ending at the high
frequency limit. The sweep time for the combination sine sweep and random vibration shall be
60 minutes per axis. The instantaneous peaks of the random vibration may be limited to 2.5
times the rms spectral acceleration level. Spectrum frequencies, frequency-function levels, and
location-function levels for the combined random and sinusoidal vibration tests are contained on
figure 5. Upon completion of this teat the valve shall be subjected to and pass the tests
specified in 4.5.2, 4.5.3, 4.5.4, 4.5.5, and 4.5.6.
e. The anti-G valve shall be subjected to vibration along each mutually perpendicular
axis. The excitation shall consist of six resonance dwells of five minutes each per axis as
follows:
(1) One in each of the frequency bands corresponding to ±10 percent of the first four
harmonics of the gun firing frequency. If no resonance is found in a frequency band, the dwell
shall be at the center frequency of the band.
(2) Dwells in the frequency range from 100 to 1000 Hz at the four most significant
resonant frequencies.
The excitation level at the dwell frequencies shall be given by the sinusoidal range curve of
figure 5. The background random excitation is not required for the dwells. Upon completion of
this test the valve shall be subjected to and pass the tests specified in 4.5.2, 4.5.3, 4.5.4, 4.5.5,
and 4.5.6.
TA8LE IV. Sine dwell. 1/
Frequency (Hz)
Cockpit acceleration (g)
33
2.50
67
5.00
100
5.00
133
5.00
167
5.00
200
5.00
233
5.00
267
5.00
1/ 7-1/2 minutes sine dwell/frequency/axis
4.5.10 Salt fog.
The valve shall be subjected to a salt fog test in accordance with method 509.4 of MIL-STD-810.
The valve shall be examined for evidence of corrosion to all exposed surfaces. If the valve
exhibits any corrosion indicative of dissimilar metals or corrosion that could preclude normal
operation or create any unsafe condition, the valve shall be rejected. The valves shall be
subjected to and pass the tests described in 4.5.2, 4.5.3, 4.5.4, 4.5.5, and 4.5.6.
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