 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B22025      ]
 ]   J. KIEL          ]    BFS PROGRAM NOTE         ] DR:  106223      ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE (X)  USER NOTE ( ) ] DATE: 08-01-91   ]
 ] RI/D (310)922-3742 ]      RELEASE NOTE ( )       ] REV A: 01-06-93  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]   OI-8F THROUGH OI-22         ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS( ) GNC( ) SEQ(X) SM/SP( ) IPL( )]     1 AND 6             ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: SEQUENCING                                       ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: MG038120/3.3.1.14 SSME HIP                     ]
 ]_____________________________________________________________________]
 ] TITLE: ERRONEOUS HYD. LOCKUP/ELEC. LOCKUP ALARMS AT SSME SHUTDOWN   ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]  DURING THE FIRST THREE CYCLES OF SHUTDOWN, THE ENGINE PHASE FLAG   ]
 ]  IN THE BFS SOFTWARE REMAINS AT MAINSTAGE PHASE (PER REQUIREMENTS)  ]
 ]  RESULTING IN ENGINE MODE INDICATIONS BEING INCORRECTLY INTERPRETED ]
 ]  IN THE FOLLOWING CASES:                                            ]
 ]  - WHEN AN SSME IS SHUTDOWN PNEUMATICALLY THE "FAIL SAFE PNEUMATIC" ]
 ]    ENGINE MODE INDICATION (ESW BITS 11-13 = '100') IS INTERPRETED   ]
 ]    AS MPS HYDRAULIC LOCKUP.                                         ]
 ]  - WHEN AN SSME IS SHUTDOWN WITH BFS IN A STANDALONE STATE AND THE  ]
 ]    ENGINE DATA FLOW IS RE-ESTABLISHED DURING THE "PROPELLANT VALVES ]
 ]    CLOSED" ENGINE MODE BY EITHER BFS ENGAGEMENT OR I/O RESET, THE   ]
 ]    "PROPELLANT VALVES CLOSED" ENGINE MODE INDICATION (ESW BITS      ]
 ]    11-13 = '011') IS INTERPRETED AS MPS ELECTRONIC LOCKUP.          ]
 ]_____________________________________________________________________]
 ] USER RESPONSE:                                                      ]
 ] +THE USER SHOULD BE AWARE THAT WHEN AN SSME IS SHUTDOWN PNEUMAT-    ]
 ]  ICALLY, WITH THE EXCEPTION OF A PNEUMATIC SHUTDOWN WITH DATA       ]
 ]  PATH FAIL OR A PREVIOUS HYDRAULIC LOCKUP FAILURE, THE BFS SOFTWARE ]
 ]  WILL ERRONEOUSLY ANNUNCIATE A CLASS 3 MPS HYDRAULIC LOCKUP ALARM   ]
 ]  AT THE TIME OF ENGINE SHUTDOWN.                                    ]
 ] +SIMILARLY, WHEN AN SSME IS SHUTDOWN WITH BFS IN A STANDALONE STATE ]
 ]  AND THE ENGINE DATA FLOW IS RESTORED (BY ENGAGEMENT OR TRACKING)   ]
 ]  DURING THE "PROPELLANT VALVES CLOSED" MODE, AN ERRONEOUS CLASS 3   ]
 ]  MPS ELECTRONIC LOCKUP ALARM WILL BE ANNUNCIATED.                   ]
 ]                                                                     ]
 ]               *** NO USER RESPONSES ARE REQUIRED ***                ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> J. AGRES          DATE 01/27/93]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:    W. R. PRUETT     DATE 02/23/93]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 03/02/93 ]
 ]PF MGR:   KENNY TODD      DATE 03/02/93]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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