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Fan system compatibility verification. |
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|  MIL-F-62564(AT)
4.7.8.4 Shock. To determine conformance to 3.4.8.5, the fan shall be mounted by normal
mounting provisions to a shock machine capable of producing the shock pulse shown in figure 2.
Three sawtooth shocks of 40 g and time duration of 11 ms (see figure 2) in each direction shall
be applied along three mutually perpendicular axis of the fan (total of 18 shocks). After the
shock test, the fan shall be operated at 5,075 rpm for 15 minutes to verify that the impeller
rotates smoothly and examined for evidence of damage or deformation.
4.7.8.5 Vibration. To determine conformance to 3.4.8.6, the fan shall be attached by its
normal mounting means either directly to the vibration exciter or transition table, or by means of
a rigid fixture capable of transmitting the vibration conditions specified herein. The fan shall be
vibrated along each axis in accordance with the test level specified in figure 1. The sweep time
shall be 15 minutes for a sweep frequency range of 5 to 500 to 5 Hz. When the fan resonance,
below 5 Hz are measured, the test curves shall be extended to 2 Hz and the sweep time shall be
18 minutes. The frequency of applied vibration shall be swept over the specified range
logarithmically in accordance with figure 3. The specified sweep time is that of an ascending
plus a descending sweep and is twice the ascending sweep time shown on figure 3 for the
specified range. The sinusodial cycling time shall be 30 minutes per axis. After the vibration
test, the fan shall be subjected to the tests specified in 4.7.5 and 4.7.6. The fan shall be examined
for evidence of damage or deformation.
4.7.9 Durability. When specified (see 6.2), durability testing shall be performed by the
Government.
4.7.9.1 Fan system compatibility verification. To determine conformance to 3.4.6.1, two
preproduction fans shall be installed in two test vehicles. The test vehicles shall be operated
under conditions that approximate vehicle initial production tests, for a minimum of 6,000 miles
each. The road conditions and mileage apportionment shall be as specified in 3.4.6.1. Fan
system mating compatibility and performance under vehicle operational environment shall be
evaluated for conformance to 3.4.6.1. Durability failures shall be observed and recorded.
4.7.9.2 Durability verification. To determine conformance to 3.4.6.2, the fan durability shall
be verified by experiencing no durability failures during 6,000 miles of vehicles operation. A
durability failure, as defined in 3.4.6.2, is the inability of the fan to perform its required function
during testing and subsequently satisfy the performance tests of 4.7.4 through 4.7.7. Fans that
must be replaced due to damage incurred as a result of failure of another component of the test
vehicle shall not be classified as a durability failure.
5. PACKAGING
5.1 Preservation, packaging, packing, and marking. Preservation, packaging, packing, and
marking for the desired level of protection shall be in accordance with the applicable packaging
requirements specified by the contracting authority (see 6.2).
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