MIL-P-5238C
3.6.12 Pump down. The pump shall be capable of maintaining rated flow and
pressure at any altitude when the head of fuel is no greater than 2 inches
With higher tempera-
above the inlet and the fuel temperature is 65°F to
ture fuel, the flow rate, pressure, altitude and fuel head shall be in accordance
with the detail specification. For dual inlet pumps, this requirement applies
to each inlet. Uncovering of one inlet shall not deteriorate the performance
of the other inlet in either the normal or the inverted position. Performance
at less than the above heads shall be in accordance with the detail specification.
3.6.13 Reprime. The pump shall be capable of self repriming within 5 seconds
following a period when the inlet is uncovered and then resubmerged in fuel.
This capability shall exist up to the maximum operating altitude of the aircraft.
The pump output depth of submersion and fuel temperature shall be in accordance
with the detail specification, provided that the fuel temperature shall be no
less than 125°F, and depth of submersion of the inlet no greater than 10 inches
of fuel.
3.6.14 Dry operation. The pump shall be capable of accumulating 100 hours of
dry operation in cycles of 5 hours each. The dry run test shall not cause any
deterioration in performance or other failure, nor shall it cause a hot spot
to develop that could ignite the fuel vapors in the tank. The peak temperature
that any portion of the housing in contact with fuel is allowed to achieve is
or as required in the detail specification, whichever is lower.
3.6. 14.1 Automatic dry cut-off. Where an integral automatic dry cut-off
feature is required by the detail specification, it shall be capable of 10,000
cycles of operation without failure or causing degradation of pump performance.
3.7 Performance. The pumps shall demonstrate satisfactory performance when
subjected to the applicable tests of table I.
3.8 Safety, reliability and maintainability
3.8.1 Safety analysis. All possible failure modes shall be examined and a
complete safety analysis, Including the impact of each failure mode, shall
be made, in accordance with MIL-STD-882.
3.8.1.1 Proof-of-safety tests. Tests shall be conducted to verify the safety
analysis. The minimum proof-of-safety tests requirements are, for electric
powered pumps, explosion and fault containment tests; for hydraulic power pumps,
overspeed and dragging impeller tests; and for all pumps, proof and burst pres-
sure tests. Additional tests shall be conducted in accordance with the detail
specification and as approved by the procuring agency The requirements of
MIL-STD-882 will be applied to the verification tests.
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