 +_____________________________________________________________________
 ] AUTHOR:            ]     RECONFIGURATION         ] DR:  108595      ]
 ] J. MCKENNA         ]       PROGRAM NOTE          ]                  ]
 ]____________________]                             ]------------------]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: 10/14/93   ]
 ] RSOC/483-4390      ]      RELEASE NOTE( )        ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI22/STS60, OI23/SPACEHAB SUBS]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]                               ]                                     ]
 ]---------------------------------------------------------------------]
 ] MAJOR SOFTWARE AREA:    PASS( ) BFS(X)] OPS MODES AFFECTED:         ]
 ] SSME**( ) DEU**( ) T&G( ) DFL/FPL**( )] 0,1,3,6                     ]
 ] TFL**( ) TCS**( ) I-LOAD( ) LEVEL C(X)]                             ]
 ]---------------------------------------------------------------------]
 ] SOFTWARE SUB-AREA: FDA, SM, PL                                      ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: JSC19478 S5.3, 7.6, 7.20, 7.21                 ]
 ]                      SS-P-0002-580/S 4.1                            ]
 ]_____________________________________________________________________]
 ] TITLE:  UNEXPECTED PAYLOAD FDA MESSAGE                              ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ] DURING INVESTIGATION OF AN UNEXPECTED "205 TDRS TRANSMIT ON A"      ]
 ] MESSAGE, AT STS-54 CITE TESTING, ANALYSIS SHOWED THAT FOR MISSIONS  ]
 ] WITH A BFS PDI INTERFACE, THE BFS MAY BE SUBJECT TO SIMILAR         ]
 ] UNEXPECTED PAYLOAD FDA MESSAGES AS SEEN WITH DR 107119.  THERE ARE  ]
 ] TWO POSSIBLE FDA MESSAGES WHICH MAY BE INCORRECTLY ANNUNCIATED      ]
 ] DUE TO A PDI DESIGN PROBLEM: NUMBER 40, "206 PL CL 2" & NUMBER 303, ]
 ] "206 PL CL 3".  AT PAYLOAD DATASTREAM INITIALIZATION, THE SYNC      ]
 ] WORD MAY OVERWRITE A PDI RAM ADDRESS. THIS ADDRESS IS A FUNCTION OF ]
 ] THE DFL LOADED IN THE DECOM.  THE INCORRECT DATA COULD CAUSE        ]
 ] UNEXPECTED FDA IF MONITORED BY THE BFS. NOTE:  THE PROBLEM DOES NOT ]
 ] MANIFEST ITSELF IN DECOM 1 DUE TO NORMAL INITIALIZATION.            ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]THIS CONDITION IS DUE TO AN UNCERTAIN LOGIC STATE OF A COMPONENT IN  ]
 ]THE LOGIC OF DECOM'S 2, 3 OR 4 AT PDI POWER UP. THIS ANOMALY CAN OC- ]
 ]CUR ONLY ONCE PER DECOM(THE COMPONENT THEN GOES TO DESIRED STATE) UN-]
 ]LESS THE PDI POWER IS CYCLED. IF THE PAYLOAD DATA AFFECTED IS ACTIVE,]
 ]VALID PAYLOAD DATA WILL OVERWRITE THE CORRUPTED DATA WITHIN ONE INPUT]
 ]DATA CYCLE PERIOD. THE GROUND (POCC) CAN CONFIRM VALID PAYLOAD DATA/ ]
 ]ERRONEOUS FDA, OR OTHER INDICATION. IF THE PAYLOAD IS NOT ACTIVE, THE]
 ]FDA MESSAGE WILL BE ANNUNCIATED ONLY ONCE AND THE CORRUPTED DATA WILL]
 ]REMAIN IN THE PDI DATA RAM. NO CREW ACTION IS REQUIRED.              ]
 ]---------------------------------------------------------------------]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RSOC:   CINDY SIMON       DATE 12/15/93]                             ]
 ]     -------------------      ---------]                             ]
 ]MOD:   WANDA L. PRICE     DATE 12/15/93]                             ]
 ]    --------------------      ---------] DARRELL E. STAMPER 12/17/93 ]
 ]SW MGR:  CHARLES STOUGH   DATE 12/15/93]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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