Figure 4-9.—Model HSU-1 fluid service unit.The original fluid container serves as a reservoirfor the H-250-1 servicing unit. This container is notopened until it is placed in the unit, and the handleassembly pressed into a locked position. When thehandle is locked, the can is sealed into the unit bycleanly piercing its top and bottom. This actionautomaticallyy destroys the can’s potential for reuse.The H-250-1 servicing unit is equipped with a toppiercing pin, which is drilled to provide the can withatmospheric venting through a 5-micron filter. Also,it has a check valve to minimize airborne particulateand moisture contamination. The lower piercing pinis drilled so the hydraulic fluid can reach the pumpthrough a passage in the base casting and a 3-micronfilter. The filter is a nonbypass type. When itbecomes loaded, the unit is inoperative. The filterhousing is designed so that the pump won’t operate ifa filter element has not been installed.A pressure gauge, an air trap, and a manual airbleed valve are attached directly to the pumpassembly base. The air trap automatically removesany air present in the fluid at the pump chamber andretains it in a separate trap. Air collected in the trap isvented from the unit by manually operating aspring-loaded, air bleed valve.The H-250-1 servicing unit has an 8-foot servicehose that is equipped with a 3-micron, in-line filterconnected at the discharge end, which preventsreverse flow contamination through the hose. Thereare several types of disconnect fittings on thereservoir service units of naval aircraft. There are nomating fittings provided with the unit. Each activitymust procure and install the disconnect fittingrequired for compatibility with the aircraft supported.Both male and female fittings are procured so thathalf can be installed on the hose end and half on thebracket provided. The bracket-mounted fittings will4-24
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