MIL-P-5238C
impose any additional velocity or turbulence at the pump inlet. This test
shall be conducted at ground level pressure with fuel at 60° to 90°F and also
at maximum altitude with fuel at the high temperature of 3.2.4. These tests
shall be repeated with output flow settings of 80 percent, SO percent, 25
percent, 10 percent, and 5 percent of rated flow. This data will be the
basis for a family of curves as shown on figure 1.
4.5.8 Reprime. The pump shall be mounted in a test tank so that it can be
rotated (or moved) to a position such that the inlet is out of the fuel. The
pump output, depth of submersion of the inlet, fuel temperature and altitude
shall be established (see 3.6.13). The pump shall then be moved to uncover
the inlet(s) for at least 15 seconds. When the pump is again submerged to
the original depth, the pump shall resume delivery of fuel at the required
flow and pressure within 5 seconds. The test shall be conducted at least
six times (twice at each of three different altitude levels). The altitude
levels shall be in accordance with the detail specification.
4.5.9 Negative G and inverted operation. The pump shall be mounted in a
test tank so that it can be rotated upside down to provide for inverted or
simulated negative G operation. The initial pump output, fuel temperature,
and altitude shall be established in accordance with 3.6.8. The pump shall
then be rotated to the inverted position. The pump output in this position
shall be in accordance with the detail specification. The pump shall be
allowed to run dry for at least 30 seconds in this position. After the pump
is rotated to the upright position in fuel, the pump shall resume delivery at
the previous flow and pressure within 5 seconds.
4.5.10 Suction feed. Fuel shall be drawn through the inoperative pump from
zero to the maximum required flow and the pressure drop data recorded.
4.5.11 Altitude climb performance. The pump shall be installed in an altitude
test tank in fresh, unweathered fuel at the high temperature of its classifica-
tion (3.2.4) with the fuel flow and head in accordance with the detail specifi-
cation. With the pump not operating, the rate of climb shall be established
in accordance with 3.2.3. The climb shall be terminated at 25,000 ft altitude
(+2,500, -1,000). Power shall be applied to the pump within 5 seconds or less
of climb termination. The pump shall achieve the required pressure and flow
within 5 seconds and shall maintain these for at least 5 minutes. This test
procedure shall be repeated at Increasing 5,000 ft intervals up to the maximum
operational altitude. The Reid vapor pressure of the fuel used in this test
shall be in accordance with the detail specification. In any case, the vapor
pressure of the fuel at the test temperature shall not be less than 2.5 psia.
During heating of the fuel there shall not be any hot spots on the surface
of the heat exchanger which exceed the maximum fuel temperature by more than
10°F. Additional start-up tests during the climb and with the alternate fuel
shall be accomplished in accordance with the detail specification.
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