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|  MIL-P-5238C
4.5. 16.1 Fuel flow The fuel flow schedule for each successive 120-hour
period of this endurance test shall be, in order:
a.
Maximum flow for 24 hours
30 percent to SO percent for 24 hours
b.
c.
2 percent to 6 percent for 20 hours
Zero flow for 4 hours (pump operating)
d.
c'.
30 percent to 50 percent flow for 24 hours
f.
Maximum flow for 24 hours.
4.5. 16.2 Fuel temperature. Each 120-hour low temperature period shall con-
sist of at least 60 hours of operation at minus
During high
temperature operation, where fuel temperatures above 135F are encountered,
the duration of temperatures above 135F may consist of only SO percent of
the total high temperature operation.
4.5. 16.3 Stopping and starting. Six times during each successive 24-hour
period of the endurance run, the pump shall be stopped for a period of 2 to
5 minutes and restarted. Upon restarting, the pump output pressure and flow
shall resume within 5 seconds maximum of the application of power. These
stopping and starting cycles shall occur at least 1 hour apart and may be
4 hours apart.
4.5. 16.4 Dual rated pumps. For pumps with a dual rating of low for normal
operation and a high for emergency of infrequent use, the maximum fuel flow
periods shall consist of maximum emergency flow for at least 10 percent of
the total time.
4.5.17 Dry endurance. A dry endurance test shall be accomplished on all
pumps to demonstrate compliance with 3.6.14. The pump shall be operated at
rated flow and allowed to pump all fuel from the tank. After the fuel has
been pumped out of the tank, the discharge valve shall be closed to prevent
circulation of air through the pump section and any fuel remaining in the
discharge line between the pump outlet and the discharge valve shall be drained.
In addition, action shall be taken to prevent contact of the pump with arty other-
residual fuel. The pump shall continue to be operated in this dry condition.
The air vapor in the tank shall be maintained at the high temperature ambient
of 3.2.4. After 5 hours of dry operation, the pump shall be stopped and the
tank refilled with room temperature fuel. The above cycles shall be accomplished
five times at sea level pressure and 15 times at the maximum operational altitude.
The instrumentation shall locate and record the maximum case temperature.
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