MIL-PRF-18953C(SH)
4.10 Test schedule. The schedule for testing the fan shall be performed in the following order:
a.
Balance (4.8.3).
b.
Casing tightness (4.8.8).
c.
Blade tip clearance measurement (4.9).
d.
Performance (4.8.4), aerodynamic stall (4.8.4.1), speed (4.8.9), motor heat (4.8.6). These tests shall be
conducted concurrently.
e.
Airborne noise (4.8.5).
f.
Vibration test (4.8.2). The correction of damages, which may have occurred during the vibration tests,
shall not be performed prior to the test specified in 4.8.1.
g.
High-impact shock (4.8.1). After conducting the high-impact shock test, tests specified in 4.8.4 and
4.8.4.1 shall be again conducted without correction of damages which may have occurred during shock
test. Data for tests specified in 4.8.4 and 4.8.4.1, one before and one after high-impact test shall
demonstrate that the fan-motor unit satisfies performance and aerodynamic stall as follows:
(1) Performance (after shock test) to be within 5 percent of the volume indicated in Figure 4
(vaneaxial fan) or Figure 5 (tubeaxial fan.
(2) The flow rate of the intersection point in 4.8.4.1.c shall not exceed the design point flow rate of
1.2.2 for vaneaxial fans by more than 5 percent.
(3) The aerodynamic stall shall not occur greater than 90% of the fan design capacity for tubeaxial
fans.
h.
Explosion (4.8.7).
4.11 Permeability tests for nonmagnetic construction. A permeability test on nonmagnetic material used in
construction of fans shall be conducted in accordance with MIL-STD-2142, Test 501 (see 3.2.3).
4.12 Maintainability demonstration. The first production unit shall be examined after testing, and the capability
to maintain, disassemble, and repair the unit shall be demonstrated. The demonstration shall be conducted utilizing
the recommended tools and with other than expert mechanics. Evidence that maintainability of the fan-motor
assembly cannot be accomplished by other than expert mechanics shall be cause for failure of the demonstration.
The maintainability demonstration shall include but not be limited to the following:
a.
Removal of fan impeller.
b.
Removal of motor.
c.
Removal of motor bearing.
5. PACKAGING
5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or
order (see 6.2). When packaging of material is to be performed by DoD or in-house contractor personnel, these
personnel need to contact the responsible packaging activity to ascertain packaging requirements. Packaging
requirements are maintained by the Inventory Control Point's packaging activities within the Military Service or
Defense Agency, or within the military service's system commands. Packaging data retrieval is available from the
managing Military Department's or Defense Agency's automated packaging files, CD-ROM products, or by
contacting the responsible packaging activity.
6. NOTES
(This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.)
6.1 Intended use. The fan-motor units specified herein are intended for ventilation and air conditioning
applications only onboard ships and craft of the United States Navy. The direction of airflow into and out of the
fans is axial. The fans are of nonsparking construction. Fans with motors rated for 65 °C ambient temperature are
standard; fans rated for 80 °C ambient, for use in unusually high ambient temperatures, are optional.
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