 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B22612      ]
 ] RENE SAUSER        ]    BFS PROGRAM NOTE         ] DR: 109626       ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:            ]
 ] (310)922-2144      ]      RELEASE NOTE ( )       ] 23 SEPTEMBER 1994]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]  OI-23 & SUBS                 ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS( ) GNC( ) SEQ(X) SM/SP( ) IPL( )]   1, 3, 6               ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: SEQ, MPS, ABORT ASCENT, ABORT ENTRY              ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: MG038120/3.3.1.6                               ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ] INCORRECT LEFT ME HELIUM INTERCONNECT DURING RTLS                   ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ] IN ORDER TO PROVIDE A REDUNDANT PATH FOR HELIUM PURGE, THE MPS DUMP ]
 ] SEQUENCE OPENS THE MPS E2 HE INTERCONNECT IN/OPEN VALVES ON FIRST   ]
 ] PASS INTO THE SEQUENCE. IN NOMINAL ASCENT THE FIRST PASS OCCURS     ]
 ] APPROXIMATELY 20 SECONDS AFTER MECO CONFIRM. IN RTLS THE FIRST PASS ]
 ] OCCURS UPON TRANSITION TO MM602 WHICH COULD BE AS LITTLE AS 14 SECS ]
 ] AFTER MECO COMMAND. IN TAL THE FIRST PASS OCCURS UPON TRANSITION TO ]
 ] MM303 WHICH DEPENDS UPON HOW QUICKLY THE CREW PROS TO MM301.        ]
 ]                                                                     ]
 ] THE SSME OPS SEQUENCE NORMALLY TERMINATES THE HE INTERCONNECT IN/OP ]
 ] COMMANDS TO ALL THREE ENGINES AT MECO CMD + 20 SEC. HOWEVER, BECAUSE]
 ] SSME OPS DOES NOT RUN PRE-ENGAGED, IF BFS IS ENGAGED BETWEEN MECO   ]
 ] AND MECO + 20 SECONDS (OR IF ET SEP HAS NOT OCCURRED AND MM102 OR   ]
 ] MM103) THEN THE SSME OPS SEQUENCE WILL BE ATTACHED AT ENGAGEMENT AND]
 ] THE 20 SECOND TIMER WILL BE RE-STARTED. AS A RESULT, IF MPS DUMP HAS]
 ] ALREADY OPENED THE E2 HE INTERCONNECT IN/OPEN VALVE BY THE TIME THE ]
 ] SSME OPS' RE-STARTED TIMER EXPIRES, THE SSME OPS WILL CLOSE THE E2  ]
 ] HE INTERCONNECT IN/OPEN VALVE AND THE REDUNDANT PATH WILL BE LOST.  ]
 ]                                                                     ]
 ] A SUBSEQUENT FAILURE DOWNSTREAM, SUCH AS A HE REGULATOR VALVE FAILED]
 ] CLOSED, COULD RESULT IN INSUFFICIENT HE SUPPLY TO PURGE THE AFT     ]
 ] COMPARTMENT OF HAZARDOUS GASSES - A POTENTIALLY DANGEROUS SITUATION.]
 ]_____________________________________________________________________]
 ] USER RESPONSE: THE REDUNDANT PATH CAN BE RECOVERED VIA CONSOLE      ]
 ] PROCEDURES WHICH DIRECT THE CREW TO MANUALLY PLACE THE LEFT HELIUM  ]
 ] INTERCONNECT VALVE SWITCH IN THE OPEN POSITION.                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> G. ALBRIGHT       DATE 10/04/94]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 10/13/94]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 10/14/94 ]
 ]PF MGR:   DON PREVETT     DATE 10/14/94]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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