MIL-DTL-26521L
4.6.3.10 Durability (see 3.6.11). A hose assembly when subjected to durability testing shall meet the
requirements of 3.6.11; the following details shall apply:
a. A hose assembly shall be installed on a hose reel.
b. The reel hub shall have a diameter of not more than 16 inches (406.4 mm) and shall be
capable of accommodating the length of hose wound in multiple layers in a single hose width
wide coil.
c. The hose shall be unwrapped from the hose reel, filled with JP-4 in accordance with
MIL-DTL-5624, JP-8 in accordance with MIL-DTL-83133 or commercial jet A and A1 fuel, and
pressurized to a hydrostatic pressure of 50 ±5 psi (345 ±34 kPa).
d. The hose shall then be evacuated through the hose reel (at least 95% of the fuel shall be
removed) and rewound on the reel.
e. Evacuation vacuum shall be 15 ± 2 inches (381 ± 51 mm) of mercury. An automotive vacuum
gage shall be installed at the outboard or nozzle end of the hose.
f. This cycle of unreeling pressurizing, evacuation and reeling shall be accomplished 1000 times.
g. The hose shall then be unreeled, rotated 180°, filled with JP-4 in accordance with
MIL-DTL-5624, JP-8 in accordance with MIL-DTL-83133, or commercial jet A and A1 fuel, and
an additional 1000 cycles accomplished.
h. The rewinding of the hose on the hose reel shall be accomplished neatly without twisting, with
the hose wound tightly.
i. At the completion of this test, the hose shall be subjected to a hydrostatic pressure of 50% of
the proof pressure in table I for not less than 3 minutes.
j. The hose shall then be destructive tested by cutting through one side of the hose longitudinally
and examined in accordance with 3.6.11.
4.6.3.11 Hose assembly cyclic surge (see 3.6.12). A hose assembly when subjected to cyclic surge
shall meet the requirements of 3.6.12; the following details shall apply:
a. A 3 foot (914 mm) hose sample that meets these specification requirements shall be fitted with
a coupling at each end.
b. After the sample is conditioned, the joint between the coupling and the hose shall withstand a
maximum cyclic surge pressure of 0 to 225 psi (0 to 1.6 MPa) for not less than 15,000 cycles.
c. Examination shall be in accordance with 3.6.12.
4.6.3.12 Coupler pressure cycling endurance test (see 3.6.13). A hose assembly when subjected to
coupler pressure cycling endurance testing shall meet the requirements of 3.6.13; the following details
shall apply:
a. The test sample shall be conditioned filling with ASTM D471 fuel B and allowing it to soak for
not less than 24 hours.
b. After the 24 hours soak period the ASTM D471 fuel B shall be drained prior to starting the
cycling test.
c. The pressure cycling test shall be started within 4 hours after draining the ASTM D471 fuel B.
d. The pressure shall be 225 psi (1.6 MPa) alternately applied for 60 seconds and then released
to 0 psi for 30 seconds at a rate of 30 cycles per hour.
e. The test shall be conducted for 15,000 cycles on a 36 inch (914 mm) hose assembly at 72°F
±2°F (22°C ±1.1°C).
f. Water may be used as the pressure test medium.
g. At the end of the test the coupling shall be carefully removed and the hose examined in
accordance with 3.6.13.
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