description  of  when  and  how  to  perform  the  job,  even down to what tools, parts, materials, and test equipment will be needed. The MRC is a situation requirement card, which means replacement of the cables is accomplished  when  certain  adverse  conditions  are  met, such  as  maximum  allowable  service  life  of  the  cables, maximum  number  of  shots  allowed,  or  reaching  the maximum  number  of  broken  wires  allowed  before replacement  becomes  necessary. Inspection  Criteria:  The cables are locally sub- jected  to  severe  atmospheric  conditions  produced  by heat and steam, which are destructive to the life of the cables. Inspection of the cables must be performed periodically (when scheduled by PMS) for visual damage,  such  as  broken  wires,  rust,  excessive  wear, kinks,  and  dirt.  Damage  to  the  cables  may  be  internal as well as external. A wire broken internally may be seen externally as such a wire will eventually work its way  to  the  outside  surface.  In  addition  to  checking  for visual damage to the cables, a record of the number of shots and the length of service must be kept for each set of cables. Any of the following conditions is cause for  replacement  of  the  retrieving  or  towing  cables: · Five or more broken wires in one rope lay. The length of wire rope in which one strand makes one complete  revolution  about  the  core  is  one  rope  lay. · Twenty or more broken wires in any 30-foot length.  The  length  of  service  and  the  number  of  shots allowed on the cables vary with the type of cables in use. · For cables with a steel core, 3,500 to 4,000 shots  or  24  months  in  service,  whichever  comes  first. Replacement  of  the  cables  (advance  or  retract)  must be made in pairs and each set must be of the same wire rope construction. This prevents uneven stretch of a pair of  cables. Catapult  Work  (Rough)  Logbook A   catapult   work   (rough)   logbook   may   be maintained  for  each  catapult  in  service,  containing  all pertinent  information  acquired  daily  on  the  operation, inspection, maintenance, testing, and repair of a catapult.  Logbooks  may  be  requisitioned  from  General Services  Administration  (GSA)  stores  under  National Stock Number 7530-222-3525. Log entries may include the  following: 1. Lubrication oil usage rate (gallons per hundred shots)  and  lubrication  schedules  completed. 2. Malfunctions (such as hangfires, slow or runaway  shots,  premature  grab  release,  failure  of  dome pressure-reducing valves, sealing strips), the malfunction cause, and  any unusual condition accompanying  the  malfunction. 3. Date, time, and type of inspection conducted, any unusual condition disclosed by the inspection, number  of  shots  on  component  part  and  catapult  system at  the  time  of  the  inspection,  and  special  information such as clearance dimensions. 4.  All  test  and  maintenance  conducted  on  compo- nents,  or  any  tests  pertinent  to  catapult  machinery. 5.  All  repairs,  replacements,  or  failures  of components, along with a full explanation of the corrective action taken. Background history of any previous  failures  may  be  included. 6. Service changes that have been incorporated, whether in whole or in part. To  maintain  continuity,  logbook  entries  should  be made  each  day.  If  launching,  inspections,  maintenance, or repairs are not conducted during a 24-hour period, a brief  log  entry  may  be  made  including  the  status  of catapult  (READY,  STANDBY,  or  SHUTDOWN),  the reason for the catapult being nonoperational, and other pertinent  information  as  directed  by  the  catapult  officer. A rough catapult logbook that has been completely filled with entries should be kept for a period of 2 years.  Books  more  than  2  years  old  should  be discarded. SUMMARY In this chapter we have described functions and operations  of  the  major  catapult  systems,  descriptions  of charging  panels  and  control  consoles,  and  general maintenance  procedures.  For  a  more  detailed  study  of the catapult systems and components, see the applicable NAVAIR technical manual with the latest revisions. 4-76