MIL-PRF-45085D
4.5.4.4.3 Heat rejection test, engine and transmission oil core assemblies, core
arrangement C. To determine conformance to 3.4.3.3, the oil entering the engine and
transmission oil core assemblies shall be at 300°F and at flow rates of 375, 300, 200, and
100 lb/min with an air temperature of 90 + 10°F to the core and at air flow rates of 80 to
180 lb/min per ft2 in 20 lb/min per ft2 increments (see figure 4).
4.5.4.5 Vibration test. To determine conformance to 3.4.4, the sample core assembly
shall be tested as specified below.
4.5.4.5.1 Test set-up. The sample core assembly shall be suspended vertically, bottom
end up, by means of two flexible cords (suggested aircraft shock cord) attached by brackets A and
B to the cooler mounting angles as shown in figure 9. With the core assembly suspended in this
manner, vibration shall be applied in a horizontal direction to one of the lower corners with the
applied vibration perpendicular to the face of the core. The vibration shall be applied to the
corner of the core assembly by means of block C as shown in figure 10. Bracket B, which shall be
constructed for mounting a vibration pick-up, and block C shall be so arranged as to be on
diagonally opposite corners of the core. Vibration pickups shall then be attached to bracket B and
block C, as shown in figures 9 and 10, for measuring vibration in a horizontal direction
perpendicular to the face of the core assembly. The core assembly shall be filled with SAE grade
10W oil and subjected to a static pressure of 100 psi during the test by use of air pressure or other
means.
4.5.4.5.2 Resonant frequency survey. With the core set-up as specified in 4.5.4.5.1,
vibration shall be applied and the frequency varied until a resonant torsional mode of vibration has
been found of 65 to 70 cycles per second (cps). Mode of vibration shall produce nodal patterns
as shown in figure 11. The peak to peak amplitude at the point of vibration shall not exceed
0.010 inch (in.) during the survey.
4.5.4.5.3 Test amplitudes. With the core assembly vibrating at the resonant frequency,
the double amplitude at the point of vibration application shall be increased to 0.0245 in. at which
time the amplitude at bracket B should be 0.0340 in. Specified amplitudes shall be maintained
within 3%. If the amplitude at the latter point is slightly different than the specified value,
adjustment shall be made as follows:
a. An increase in the amplitude at bracket B may be obtained by a slight decrease in
the frequency while still maintaining the same amplitude at the point of vibration
application at block C. A decrease in the amplitude at bracket B may be obtained
by a slight increase in the frequency, while still maintaining the same amplitude at
the point of vibration application, block C.
b. When originally setting up the specified amplitudes, the amplitudes should be
increased slowly so as to not exceed the specified amplitudes. Setting the
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