 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] L. FARRELL         ]    PASS PROGRAM NOTE        ]   46526          ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: SEPT. 1987 ]
 ] DEV/282-7343       ]      RELEASE NOTE( )        ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI2 AND SUBS                  ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G2                              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  ORBIT, OMS, RCS                                 ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 4.212, 4.101                                   ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ] HE/VAP ISO VLV CMDS TERMINATED BY ORBIT OMS/RCS INTERCONNECT        ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ] IF OMS/RCS GAUGING IS ACTIVE DURING AN OMS OR RCS BURN IN MM202     ]
 ] AND THE OMS A AND B HE PRESS/VAP ISO SWITCHES ARE IN THE GPC        ]
 ] POSITION, THE OMS/RCS INTERCONNECT SEQUENCER CAN SHUTDOWN THE OMS   ]
 ] ENGINES AND AFT RCS JETS BY TERMINATING THE HELIUM AND VAPOR        ]
 ] ISOLATION VALVE COMMANDS. THERE ARE TWO SCENARIOS:                  ]
 ]                                                                     ]
 ] A. OMS/RCS GAUGING IS TERMINATED VIA ITEM 7 ON SPEC 23. THIS        ]
 ]    SCENARIO WILL CAUSE THE LEFT AND RIGHT HELIUM/VAPOR VALVE        ]
 ]    COMMANDS TO BE TERMINATED.                                       ]
 ]                                                                     ]
 ] B. THE AUTOMATIC OMS TANK REPRESSURIZATION I-LOADED TIMER           ]
 ]    EXPIRES DURING THE BURN. THIS SCENARIO WILL ALSO CAUSE THE       ]
 ]    LEFT AND RIGHT HELIUM/VAPOR VALVE COMMANDS TO BE TERMINATED;     ]
 ]    HOWEVER, WHEN THE OMS TANK PRESSURE DROPS BELOW AN I-LOADED      ]
 ]    THRESHOLD, THE VALVES FOR THE POD FOR WHICH GAUGING IS ACTIVE    ]
 ]    WILL BE REOPENED.                                                ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ] THE CREW CAN PREVENT THE PROBLEM BY EITHER:                         ]
 ]                                                                     ]
 ] A. NOT EXECUTING ITEM 7 DURING THE BURN; OR                         ]
 ]                                                                     ]
 ] B. KEEPING EITHER THE A OR B OMS HELIUM/VAPOR SWITCH IN THE         ]
 ]    "OPEN" POSITION DURING THE BURN.                                 ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM: WYATT COOPER         DATE 07/27/88]                             ]
 ]    --------------------      ---------]                             ]
 ]SSD: SAM ANKNEY           DATE 08/02/88]                             ]
 ]    --------------------      ---------] JACK G BOYKIN      08/17/88 ]
 ]PF MGR: KENNETH R KROLL   DATE 07/29/88]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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