receptacle for free water. If free water is seen, decontaminate the system according to applicable procedures. Contamination Analysis Normally, contamination analysis of SE fluid samples is accomplished by using the contamination analysis kit. You may use other approved measurement methods, if available or if required. Decontamination of unacceptable equipments is performed by recirculation cleaning, purifying, flushing, or purging, as required; these actions are performed by the supporting activity. Recirculation Cleaning Recirculation cleaning is used when equipment is unacceptably contaminated with particulate matter (in excess of Navy Standard Class 3), but the fluid is otherwise considered satisfactory. In recirculation cleaning, the equipment is self-cleaned using its internal filters, the 3-micron elements in particular. You begin by operating the contaminated SE so maximum circulation of fluid through the equipment reservoir and internal 3-micron filters occurs. Maintain the flow long enough to allow a total flow equivalent to at least five times the total fluid capacity of the equipment reservoir. Monitor all filter differential-pressure indicators throughout the operation. If elements appear to be loaded, check and replace them. You should resample and analyze the fluid from the reservoir. If improvement is shown, but the contamination level is still excessive, repeat the process. If there is still no improvement, try to find the internal contamination source, such as a failed component. Replace any components you determine to be contaminating the fluid, and continue decontamination by draining, flushing, and refilling the equipment with new filtered fluid. Recirculation clean and resample, as before, to determine acceptability. When you find the fluid samples from the reservoir to be within acceptable limits, recirculation cleaning may be terminated. Flushing Flushing is used to decontaminate SE heavily contaminated with particulate matter, or when the fluid contains a substance not readily removed by the internal filters. To begin the flushing procedure, you drain, flush, and reservice the equipment reservoir using new filtered fluid. If contamination originated at the pump, drain and flush the hoses and lines directly associated with the pump output separately. Operate the equipment so fluid flows through all circuits. Allow output (or return line) fluid to dump overboard into a waste receptacle. Continue flushing until a quantity of fluid equal to the equipment reservoir capacity has passed through the unit. Closely monitor the reservoir level during the operation, adding new filtered fluid, as required. This prevents the reservoir level from dropping below the one-third full point, Take a sample and analyze the output and the reservoir fluids. If the contamination level shows improvement but is still unacceptable, repeat the flushing operation. If extensive flushing fails to decontaminate the equipment, you should request assistance from the supporting engineering activity. Upon successful completion of system flushing, recirculation clean the equipment for a minimum period. Then, take a sample from the system to verify the contamination level as being acceptable. When you have done this, service the reservoir. Purging Purging of SE hydraulic systems is performed only upon recommendation from, and under the direct supervision of, the cognizant engineering activity. It is the responsibility of the cognizant engineering activity to select the required cleaning agents, provide detailed cleaning procedures, and perform tests upon completion of purging to ensure satisfactory removal of all cleaning agents.    Whenever possible, purging operations are to be accomplished at a naval aviation depot facility (NADEP). Intermediate maintenance activities are not authorized to perform system purging without direct depot supervision. 4-40