MIL-PRF-83772C
minute. The hose shall then be proof pressure tested per paragraph 4.4.4. The hose assembly
shall maintain the 150 ±5 psig pressure for at least 1 minute.
4.4.6 Abrasion drag test. The hose assembly shall be placed on a dry, brushed concrete
surface, such as a runway, and dragged a distance of at least 20,000 feet at a speed of 4 to 5
MPH. The end of the hose with the male end fitting shall be approximately 18 inches above the
ground, held stationary, and shall be horizontally oriented with the centerline of the hose
pointing in the direction being dragged. The hose shall be visually inspected each 5,000 feet and
at the end distance of 20,000 feet. The extent of wear shall be recorded, as specified by the test
documentation requirements (see 6.2), at each inspection. Fraying or the development of sharp
edges that would be dangerous in operational use shall be considered structural damage.
4.4.7 Servicing test. The hose assembly shall be connected to a source capable of
providing 45 ±5 psi pressurized liquid nitrogen. The environment to which the hose assembly is
exposed during aircraft servicing shall be duplicated to the maximum extent practical:
a. With a service of 45 ±5 psi, purge the hose assembly and record the time it takes to
complete purging (see 6.3.3). The total purging time, from opening of the pressurized liquid
nitrogen source to when liquid nitrogen begins flowing out through the hose and aircraft filler
valves, shall not exceed 2 minutes. Once liquid nitrogen begins flowing, close off the source of
the liquid nitrogen to the hose assembly.
b. The hose assembly shall next be subjected to a series of 50 servicing cycles. Each
cycle shall consist of:
(1) Opening the source of liquid nitrogen.
(2) Flowing liquid nitrogen through the hose assembly into a discharge vessel.
(3) Discharging 30 to 45 ounces of liquid nitrogen into the discharge vessel.
(4) Shutting of the source of liquid nitrogen.
(5) Repeating the cycle after a 3 minute waiting period, until 50 cycles are
accomplished.
The hose assembly shall complete the 50 servicing cycles without leakage or visible
damage as the result of the servicing test.
4.4.8 Continuity test. The hose assembly shall be checked to verify that there is
electrical continuity through the hose assembly when measured from one end fitting to the other
end fitting.
4.4.9 Burst pressure test. The hose assembly shall be hydrostatically pressurized at the
completion of all tests at rate not to exceed 50 psig per minute until ruptures. There shall be no
failure of the hose or its end fittings at a pressure less than 500 psig.
8
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business