1+_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] L. STRADER         ]    PASS PROGRAM NOTE        ]       102432     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  08/19/88  ]
 ] IBM/282-7148       ]      RELEASE NOTE( )        ] REV C: 02/12/93  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]  OI-8A AND SUBS               ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G6, G1, G3, G2, G8              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  RCS, OMS, ABORT                                 ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS:  4.190, 4.58, 4.191                            ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]         POSSIBLE SIMULTANEOUS SHUTDOWN OF ALL FIRING RCS JETS       ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ]   THE PASS DESIGN (PER LEVEL A REQUIREMENTS) MAY SKIP A PROCESS     ]
 ]   CYCLE IF THE PROCESS IS IN EXECUTION AT THE TIME THE NEXT CYCLE   ]
 ]   IS TO BE STARTED.  THEREFORE, THE FLIGHT SOFTWARE CANNOT SUPPORT  ]
 ]   THE LEVEL C REQUIREMENT TO TOGGLE THE RCS 'A' FIRE COMMAND EVERY  ]
 ]   40 MSEC IN THE EVENT OF A PASS HFE CYCLE OVERRUN OR DURING INI-   ]
 ]   TIATION OF BFS ENGAGE.  IN THESE EVENTS THE TOGGLE MAY NOT BE RE- ]
 ]   SUMED FOR 120 MSEC OR MORE, AND ANY RCS JETS THAT WERE FIRING WILL]
 ]   BE SHUT DOWN.  A SIMULTANEOUS SHUTDOWN OF A LARGE NUMBER OF RCS   ]
 ]   JETS (I.E., A 24-JET NULL DUMP) WILL VIOLATE SYSTEM CONSTRAINTS   ]
 ]   AND MAY RESULT IN DAMAGE TO THE RCS AND OMS PROPELLENT DISTRIBU-  ]
 ]   TION SYSTEMS.  THE CYCLE OVERRUN COULD ALSO RESULT IN FIRING JETS ]
 ]   FOR LESS THAN THE MINIMUM FIRING TIME (POTENTIAL ZOT DAMAGE IF    ]
 ]   MORE THAN ONE OCCURRENCE WITHIN 320 MSEC).  NOTE: A PROCESS CYCLE ]
 ]   OVERRUN RESULTS IN A 020D GPC ERROR.                              ]
 ]                                                                     ]
 ]   THE RATIONALE FOR WAIVING THESE POTENTIAL SYSTEM CONSTRAINT VIO-  ]
 ]   LATIONS IS BASED ON:                                              ]
 ]                                                                     ]
 ]      (1) FOR MISSIONS WHERE NO ABORT INTERCONNECTED DUMPS ARE       ]
 ]          PLANNED, THE EXPOSURE TO 24 JET SIMULTANEOUS SHUTDOWN      ]
 ]          DOES NOT EXIST.                                            ]
 ]                                                                     ]
 ]                                                                     ]
 ]                      - CONTINUED -                                  ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM:   JEAN L. ZOPHY      DATE 04/06/93]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 04/15/93]                             ]
 ]     -------------------      ---------]                             ]
 ]PF MGR:KIRK A. SHIREMAN   DATE 04/27/93] DARRELL E. STAMPER 05/03/93 ]
 ]       K. S. LINDSAY           04/27/93]------------------- -------- ]
 ]       MARK M. HAMMERSCHMIDT   04/30/93] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
 @


1+_____________________________________________________________________
 ]                                                                     ]
 ]                       SUPPLEMENTAL SHEET                            ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ] L. STRADER         ]    PASS PROGRAM NOTE        ]       102432     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  08/19/88  ]
 ] IBM/282-7148       ]      RELEASE NOTE ( )       ] REV C: 02/12/93  ]
 ]____________________]_____________________________]__________________]
 ] TITLE:                                                              ]
 ]        POSSIBLE SIMULTANEOUS SHUTDOWN OF ALL FIRING RCS JETS        ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ]     (2)  FOR MISSIONS WHERE ABORT INTERCONNECTED DUMPS ARE PLANNED, ]
 ]          ADDITIONAL RCS OR OMS FAILURES ARE REQUIRED TO PRODUCE A   ]
 ]          DAMAGING SHUTDOWN TRANSIENT.  ANALYSIS OF THE SYMMETRICAL  ]
 ]          SIMULTANEOUS SHUTDOWN OF TWENTY-FOUR JETS WITH TWO OMS     ]
 ]          ENGINES FIRING PREDICTS AN ACCEPTABLE LINE TRANSIENT.      ]
 ]          HOWEVER, THIS CONDITION HAS NOT BEEN TESTED.  ADDED POST   ]
 ]          FLIGHT TESTS AND INSPECTIONS WOULD BE REQUIRED IF THE      ]
 ]          CONDITION WERE TO OCCUR.  COMBINATIONS OF FEWER JETS,      ]
 ]          UNSYMMETRICAL SHUTDOWN, OR SHUTDOWN WITHOUT BOTH OMS TANKS ]
 ]          AND BOTH OMS ENGINES ON LINE MAY RESULT IN UNACCEPTABLE    ]
 ]          SURGE CONDITIONS.                                          ]
 ]                                                                     ]
 ]     (3)  LOW PROBABILITY OF CONSECUTIVE OVERRUNS RESULT IN NO       ]
 ]          SIGNIFICANT INCREASE IN VULNERABILITY TO ZOT DAMAGE.       ]
 ]                                                                     ]
 ]     (4)   "CONSECUTIVE" IS DEFINED IN THIS CASE AS MEANING MORE     ]
 ]           THAN ONE OCCURRENCE IN ANY GIVEN 320 MSEC TIME PERIOD.    ]
 ]                                                                     ]
 ]     (5)   REFERENCE PRCB WAIVER #41596.                             ]
 ]                                                                     ]
 ]                                                                     ]
 ]   ADDITIONAL SCENARIOS THAT MAY LEAD TO VIOLATIONS OF THE SAME      ]
 ]   SYSTEM CONSTRAINTS ARE:                                           ]
 ]                                                                     ]
 ]      .  DATA HOMOGENEITY VIOLATIONS                                 ]
 ]      .  BFS ENGAGE                                                  ]
 ]      .  OPS TRANSITION                                              ]
 ]      .  GPC FAILURE                                                 ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ]   BE AWARE OF THIS SITUATION.                                       ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 @
