TM 1-1500-204-23-1 (2) When aircraft is being serviced with oxygen within 50 feet of an area where smoking is permitted, NO SMOKING   signs   shall   be   placed   at   a   50-foot   radius around the servicing area. (3) All aircraft parked outside will be grounded and    bonded,    in    accordance    with    FM    1-500,    to    the aerospace    ground    equipment    while    servicing    oxygen systems CAUTION Oxygen equipment shall be kept clean at   all   times.      No   organic   matter   or flammable   substance   of   any   nature shall   be   allowed   to   contact   oxygen. Ensure   that   all   components   of   the systems  are  free  of  moisture,  oil,  and grease   at   all   times.      Oxygen   is   a nonflammable gas; however, it supports  combustion  and  lowers  the flash or Ignition point of all combustible  materials.    Oxygen  shall be handled as a flammable gas. (4) To  prevent  overfilling  of  tanks,  personnel shall  observe  aircraft  oxygen  system  gauges  at  all  times during servicing operation. (5) Personnel  shall  be  stationed  at  the  oxygen servicing  unit  at  all  times  during  servicing  operation  to shut    off    unit    valves    immediately    upon    receiving    a command from personnel watching aircraft system gauge. (6) Service     aircraft     from     cylinders     clearly labeled    DRY    or    AVIATOR'S    BREATHING    OXYGEN. Other Oxygen may have moisture which could cause flow stoppage at temperatures below freezing. (7) Always    use    a    pressure-reducing    device when   servicing   low-pressure   oxygen   system   from   high pressure bottles. (8) Fill     oxygen     system     slowly     to     prevent explosion resulting from heat generated by filling too fast. (9) An   aircraft   oxygen   system   not   equipped with   shutoff   devices   at   cylinders   shall   be   completely discharged of all pressure prior to removing components. All   electrical   power   shall   be   shut   off   during   oxygen discharge operations. (10) Refer   to   applicable   aircraft   maintenance manual    for    additional    information    and    maintenance procedures. 9-18.  Relief  Tube  System.    Maintenance  of  relief  tubes primarily   consists   of   cleaning   and   replacing   of   parts. Clean or replace parts using the following procedures: a. To   clean   and   deodorize   relief   tube   systems,   a solution  of  1  1/2  ounces  of  MIL-SPEC  A-A-1634  general purpose deodorant and 5 gallons of water will be used to wash area around relief tube exit and relief tube entrance. b. Pour   remainder   of   solution   through   the   tube. When an offensive odor remains, use a stronger solution and reclean until odor is removed. NOTE The area of relief tube exhaust will be primed  with    zinc    chromate    primer, Federal   Specification  TT-P-1757,   and painted with acid proof lacquer, Federal Specification TT-L-54 c. Replace  deteriorated  hose,  broken  or  damaged horn, and broken or damaged attaching parts. NOTE Install   hose   so   as   to   eliminate   any residue pockets. 9-19.  Windshield   Wiper   System.        Maintenance    and adjustment of the windshield wiper system is explained in the following paragraphs. a. Maintenance  of  Windshield  Wiper  System.  The maintenance   of   the   windshield   wiper   system   consists primarily of replacement of defective parts, as follows. (1) Replace   wiper   motor,   wiper   units,   wiper arms,  and  flexible  cables  that  are  inoperative,  cracked, bent or otherwise defective. (2) Replace      wiper      blades   that   are      worn, deteriorated,  or  torn,  or  when  rubber  has  lost  its  elastic qualities. 9-42