MIL-DTL-27267D
b. For qualification testing, 2 of the 6 samples shall be unaged while 2 samples shall be aged in air
at 400°F ±10°F (204°C ±5.5°C) for 168 hours. The remaining 2 samples shall be aged by
immersion in fluid in accordance with MIL-PRF-7808 at 400°F ±10°F (204°C ±5.5°C) for 168
hours.
(1) The assemblies shall then be subjected at room temperature to the proof pressure
specified in table III for a minimum of 5 minutes.
(2) The hose assemblies shall then be pressurized to operating pressure and while
maintaining this pressure at room temperature, the hose assemblies shall be immersed in
a 3.5% +0.1% U.S.P. Grade NaCI solution by weight for 8 to 10 minutes, then allow to air
dry for the remainder of 1 hour. This sequence of immersion and air drying shall be
repeated no less than 50 times.
c. Samples sizes 12 and smaller shall be connected to the rigid supports of the test apparatus and
bent to the applicable radius specified in table III. Samples sizes -16Z and larger shall be
installed straight; one end may be left free.
d. The peak pressure used for samples shall be 100% of operating pressure specified in table III.
4.6.3.5 Stress degradation. Hose assemblies when stress degradation tested shall meet the
requirements of 3.5.3.5, the following details shall apply:
a. Two hose assemblies of each size shall be subjected to this test. The hose assemblies shall be
filled with high temperature test fluid in accordance with MIL-PRF-7808 or MIL-PRF-83282.
b. The hose assemblies shall then be placed in an oven which shall be maintained at a
temperature of 450°F ±10°F (232°C ±5.5°C). Precautions shall be taken to assure that the hose
assemblies do not come in contact with part of the oven that are at a higher temperature. A
pressure equal to the rated operating pressure specified in table III shall be applied to the hose
assemblies.
c. After a minimum of 20 hours at 450°F ±10°F (232°C ±5.5°C), the pressure shall be gradually
released and the assemblies shall be removed from the oven, drained and cooled to room
temperature. The assemblies shall then be flushed with a quantity of new test fluid, equivalent in
volume to at least twice the sample volume and drained.
d. The hose assemblies shall then be filled with MIL-PRF-87257 fluid. A pressure equal to the
rated operating pressure specified in table III shall be applied and held for a minimum of 2 hours
at room temperature.
e. The assemblies shall then be emptied and filled with oil or hydraulic fluid as specified in
f. The hose assemblies shall then be filled with ASTM reference fluid B (isooctane, 70%; toluene,
30%) in accordance with ASTM D471 and individually capped. While at room temperature, the
assemblies shall be bent around a mandrel having a radius equal to the minimum bend radius
as specified in table III. The assemblies shall be bent around the mandrel and straightened for
20 cycles. The assemblies shall be held by the fitting while the bending is being performed. The
tests specified in 4.6.3.5 (a), (b), (c), and (d) shall be conducted for the third time.
g. Within 4 hours after the final 2 hours pressurization period with ASTM reference fluid B, the
assemblies shall be drained and flushed with fluid in accordance with MIL-PRF-680 and placed
in an oven for 1 hour. The temperature of the oven shall be maintained at 160°F ±10°F (71°C
±5.5°C).
h. Within 8 hours after completion of the drying process, the hose assemblies shall be removed
from the oven, cooled to room temperature, and then subjected to an air-under-water test. To
conduct this test, the hose assemblies shall be installed in an apparatus similar to that shown on
figure 1.
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