should change the defective pumps, check filter elements, and decontaminate the system as required. Check the applicable MIM for corrective action to be taken regarding decontamination of the system. If this action is not taken, the complete system could be contaminated. Hydraulic systems and components are serviced by using approved fluid dispensing equipment only. Unfiltered hydraulic fluid should NEVER be introduced into systems or components. All portable hydraulic test stands must receive the required periodic maintenance checks. Make certain that each unit is approved, and the applicable MIM is readily accessible and up to date. When the portable hydraulic test stand is not in use, it should be protected against contaminants such as dust and water. You should ensure that correct hoses are used on each stand, and that they are approved for the type of fluid being used. Properly cap hoses when they are not being used. Hoses must be serialized and must remain with the equipment. Make sure the hoses are coiled, kept free of kinks, and properly stowed. Make sure they are in satisfactory condition and are checked periodically. Replace any hose that exhibits fluid seepage from the outer cover or separation between the inner tube and the outer cover. Portable hydraulic test stands that show indications of contamination or that have loaded (clogged) filters are removed from service immediately and returned to the supporting activity for maintenance. Use only approved lubricants for O-ring seals; incorrect lubricants will contaminate a system. Many lubricants look alike, but few are compatible with hydraulic fluids. The only approved O-ring seal lubricants are hydraulic fluid MIL-H-5606, hydraulic fluid MIL-H-83282, hydraulic fluid MIL-H-46170, or a thin film of grease, MIL-G-81322. MAINTENANCE PRACTICES Good housekeeping and maintenance practices help eliminate problems caused by contamination. Be careful if you work on a hydraulic system in the open, especially under adverse weather conditions. Use caution if you work on hydraulic equipment near grinding, blasting, machining, or other contaminant-generating operations. Often, you cannot see harmful grit. Do not break into hydraulic systems unless absolutely necessary (this includes cannibalization). Use the proper tools for the job. Use only authorized hydraulic fluid, O-rings, lubricants, or filter elements. When dispensing hydraulic fluid, make sure you use an authorized fluid service unit. Check to make sure that the hydraulic fluid can is clean before it is installed. After use, dispose of all empty hydraulic fluid cans and used hydraulic fluid in accordance with Navy and local hazardous material (HAZMAT) instructions. Keep hydraulic fluid in a closed container at all times. Keep portable hydraulic test stand reservoirs above three-quarters full. Seal all hydraulic lines, tubing, hoses, fittings, and components with approved metal closures. You should not use plastic plugs or caps because they are possible contamination sources. Install quick-disconnect dust covers. Store unused caps and plugs in a clean container. Remove exterior contaminants by using approved wiping cloths. Lint-free wiping cloths should be used on surfaces along the fluid path. If possible, have the replacement component on hand for immediate installation upon removal of defective component. Replace filters immediately after removal. If possible, fill the filter bowl with proper hydraulic fluid before you install it to minimize the induction of air into the system. Do not reset differential pressure indicators if the associated filter element is loaded and in need of replacement. When cleanable filter elements are removed from hydraulic systems, put them in individual polyethylene bags and forward them to the intermediate- or depot-level maintenance activity for cleaning. Do not clean cleanable filter elements by washing them in a container and blowing them out with shop air. Cleanable filter elements must be cleaned and tested according to applicable procedures before they are reused. Clean all connections, interconnect the pressure and return lines of the stand, and circulate the hydraulic fluid through the test stand filters before connecting portable hydraulic test stands to aircraft. NOTE: Do not use chlorinated solvents to clean connectors. Use dry-cleaning solvent P-D-680 or filtered hydraulic fluid. Store O-rings, tubing hoses, fittings, and com- ponents in clean packaging. Do not open or puncture individual packages of O-rings or backup rings until just before you use them. Do not use used or unidentifiable O-rings. Replace seals or backup rings with new items when they have been disturbed. Use the correct O-ring installation tool when you install O-rings over threaded fittings to prevent threads from damaging the O-ring. 4-3