TM 55-1930-209-14&P-19 Table 3-3. Preventive Maintenance Checks and Services for ROWPU System (Continued) B - Before D - Daily Q -  Quarterly D - During W - Weekly S -  Semiannually A - After M - Monthly A -  Annually INTERVAL ITEM PROCEDURES EQUIPMENT ITEM TO BE CHECK FOR AND HAVE IS NOT READY/ NO. INSPECTED REPAIRED OR ADJUSTED AVAILABLE IF B   D   A   D  W  M   Q   S   A AS NECESSARY * * c.  Remove used filter elements.  Keep upper seals separate from lower seals. NOTE Examine used filter elements.  If they con- tain large amounts of sand the frequency of replacement has increased, check media fil- ters for internal damage. * * d.  Discard used filter elements. * * e.  Clean internal parts and inside of filter housing with a stiff bristle brush and clean water and dry with clean, lint-free cloths. * * f.  Inspect upper and lower spiders.  Check Spiders are bent. seals for damage and replace if nicked. Place new or reused upper seals in sockets on upper spider.  Place lower seals on guide pins on lower spider. * * g.  Place three new filter elements in three center sockets on upper spider.  Make sure upper seals remain properly seated. * * h.  Place lower spider on assembly so that tie rod holes on spider align with tie rods and center guide pins just engage filter core tubes. * * i.  Make sure seals remain in sockets and place nine outer filter elements in outer sockets on upper spider.  Make sure upper and lower seals are properly seated for each filter. * * j.  Install six washers, three springs, and Springs are missing. three hex nuts on spider tie rod ends. Hand tighten until nuts contact top washers. Tighten hex nuts evenly another seven turns each to compress but not to completely flatten spring. 3-24