TAVIS FAILURE ANALYSIS

MSFC Record #
A15483

In-Flight Anomaly Number
--

Contractor Report Number
E-152

JSC#
--

KSC#
--

Problem Title
LOX ULLAGE PRESSURE TRANSDUCER FAILED OUTPUT VOLTAGE TEST AT MAF

EICN#
--

ELEMENT
ET

Contractor
MMMSS

FSCM#
--

FCRIT
3

HCRIT
--

Sys_Lvl
N

Misc Codes
A B C D E F G H I J K L M N O

HARDWARE
EIM

NOMENCLATURE
--

PART#
--

SER/LOT#
--

MANUFACTURER
--

HARDWARE
LRU

NOMENCLATURE
--

PART#
--

SER/LOT#
--

MANUFACTURER
--

HARDWARE
NCA

NOMENCLATURE
LOX PRESS TRANSDUCER

PART#
80931003731-009

SER/LOT#
0000028

MANUFACTURER
TAVIS CORP

Test/Operation
A - ATP

Prevailing Condtion
F - FUNCTIONAL

F / U
F

Fail Mode
EG - SIG HI OR LO

Cause
MAW - MFG-ASY-WORK

System
ELECTRICAL

Defect
MW - MISWIR

Material
C - EEE

Work Contact
JOHN ADAMS

Fail Date
08/17/1992

Received at MSFC
06/24/1993

Date Isolated
08/17/1992

FMEA Reference
3.2.1.1C & 3.2.1.2C

IFA: Mission Phase
--

Mission Elapsed Time
--

Location
MAF

Symptom
EG - SIG HI OR LO

Time Cycle
--

Effectivity Text
--

Vehicle Effectivity Codes

Vehicle 1
--

Vehicle 2
--

Vehicle 3
--

Vehicle 4
--

Vehicle 5
--

Mission Effectivity Codes

Mssn 1
--

Mssn 2
--

Mssn 3
--

Mssn 4
--

Mssn 5
--

Estimated Completion Dates

MSFC Approved Defer Until Date
01/17/1994

Contractor Req Defer Until Date
02/08/1994

LVL 3 Close
--

Remark / Action
02/08/1994

Investigation / Resolution Summary

Last MSFC Update
02/09/1995

CN RSLV SBMT
02/09/1994

Defer Date
--

Add Date
06/24/1993

R/C Codes
2 - MFG -- --

Assignee

Design
R. MOYE

Chief Engineer
M. PESSIN

S & MA
R. JACKSON

Project
--

Project MGR
P. COUNTS

Approval

Design
R. MOYE

Chief Engineer
M. PESSIN

S & MA
R. JACKSON

Project
--

Project MGR
P. COUNTS

PAC Assignee
B. HURST

PAC Review Complete
BH

MSFC Closure Date
02/23/1994

Status
C - CLOSED

F/A Completion
06/15/1993

Problem Type
--

SEV
--

Program Name
--

REVL
--

OPRINC
--

FUNC MOD
--

Software Effectivity
-- -- -- -- --

Software Fail CD
--

SUBTYPE
--

Software Closure CD
--

RES PERSON L2
--

Approval Signature L3
--

Related Document Type
--

Related Document ID
T-123647

Related Document Title
--

Related Document Type
--

Related Document ID
--

Related Document Title
--

Related Document Type
--

Related Document ID
--

Related Document Title
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Contractor Status Summary

Reliability/Quality Assurance Concerns, Recommendations:

Problem Description

A LOX ULLAGE PRESSURE TRANSDUCER FAILED A TEST OF OUTPUT VOLTAGE

VERSUS APPLIED PRESSURE DURING ACCEPTANCE TESTING OF ET-65/LWT-58

FAILURE ANALYSIS OF THE TRANSDUCER, COMPLETED JUNE 15, 1993,

IDENTIFIED THE ROOT CAUSE OF THE FAILURE AS A DEFECTIVE TRANSISTOR

THE NATURE OF THE TRANSISTOR DEFECT INDICATES A LOT RELATED PROBLEM

THE TRACING OF ALL USES OF THE DEFECTIVE LOT OF TRANSISTORS WAS

RECEIVED ON JUNE 17, 1993

CRITICALITY: THE PD7400239-009 TRANSDUCERS ARE USED ON ET-64/

SUBSEQUENT AND ARE CRIT. 3; FMEA ITEM CODE 3.2.1.1C, "FAILS WITH HIGH

READING;" AND FMEA ITEM CODE 3.2.1.2C, "FAILS WITH LOW READING."

NOTE: THE TRANSDUCERS ARE LIMITED LIFE CONTROLLED

PREVIOUS CAPS: CAPS E-132, E-133, AND E-141 ADDRESSED UNRELATED

PROBLEMS WITH PD7400239 TRANSDUCERS

REVISION "E" CLOSES ALL TASKS. SEE ASTERISKS FOR CHANGES

Contractor Investigation/Resolution

GENERAL:

A LOX ULLAGE PRESSURE TRANSDUCER INSTALLED ON ET-65/LWT-58 FAILED A

TEST OF THE ACCURACY OF THE OUTPUT VOLTAGE PRESSURE VERSUS THE APPLIED

PRESSURE. THE TEST, TP7C201-AT, WAS BEING PERFORMED IN THE MAF

BUILDING 420, FINAL ACCEPTANCE AND TEST WORK AREA

THE TRANSDUCER WAS A PART NUMBER 80931003731-009, SERIAL NUMBER 28,

INSTALLED ON THE ET IN THE REFERENCE DESIGNATOR 327A04 POSITION. AT

AN APPLIED PRESSURE OF 21.006 PSIG, THE OUTPUT VOLTAGE WAS 3.581 VDC

THE MAXIMUM ALLOWABLE OUTPUT VOLTAGE AT THAT PRESSURE IS 3.560 VDC

THE 0.021 VDC OUT-OF-TOLERANCE CONDITION IS EQUIVALENT TO AN ERROR OF

0.4% OF FULL SCALE. THE 80931003731-009 TRANSDUCER IS AN ASSEMBLY OF A

PD4800280-019 METAL SCREEN FILTER INSTALLED ON THE REFERENCE PORT OF A

PD7400239-009 PRESSURE TRANSDUCER. THE PD7400239 TRANSDUCER, SERIAL

NUMBER 85, USED IN THIS ASSEMBLY HAD AN OUTPUT VOLTAGE THAT WAS LOWER

BY 0.9% AT 21 PSIG DURING THE ORIGINAL SUPPLIER ACCEPTANCE TEST

THE TRANSDUCER WAS RETURNED TO THE SUPPLIER, TAVIS CORPORATION, FOR

FAILURE ANALYSIS. THE TRANSDUCER IS A HERMETICALLY SEALED DESIGN

WITH A TUBULAR STAINLESS STEEL CASE. ANALYSIS PROVED DIFFICULT AS

THE FAILURE WAS INTERMITTENT AND VARIABLE IN NATURE. THE ANALYSIS

AT TAVIS CONCLUDED IN APRIL 1993, BY IDENTIFYING A DEFECTIVE

TRANSISTOR. THE DEFECTIVE TRANSISTOR WAS SENT TO THE MARTIN

MARIETTA ASTRONAUTICS GROUP IN DENVER, COLORADO,FOR FURTHER

ANALYSIS

THE DEFECTIVE TRANSISTOR WAS A 2N2946A JANTXV, PRODUCED BY TELEDYNE

CRYSTALONICS, LOT CODE 8619. IT WAS FOUND TO HAVE EXCESSIVE

ELECTRICAL LEAKAGE AT ALL TEMPERATURES; THE GREATEST OUT OF

TOLERANCE CONDITION OCCURRED AT 75 DEGREE F. TESTING FOUND THE

TRANSISTOR CASE HERMETICITY WAS WITHIN SPECIFICATION. RESIDUAL GAS

ANALYSIS (RGA) OF THE CONTENTS OF THE HERMETICALLY SEALED CASE

FOUND THE MOISTURE CONTENT WAS 6.79%; THE MAXIMUM ALLOWABLE VALUE

IS 0.5%. FOLLOWING RGA, WITH THE MOISTURE HAVING BEEN REMOVED, THE

TRANSISTOR NO LONGER HAD EXCESSIVE ELECTRICAL LEAKAGE. EXCESSIVE

INTERNAL MOISTURE INDICATES LOSS OF CONTROL DURING THE

MANUFACTURING PROCESS AND BRINGS INTO QUESTION THE RELIABILITY OF

THE ASSOCIATED PRODUCTION LOT

TAVIS CORPORATION IDENTIFIED ALL PARTS PRODUCED FOR MARTIN MARIETTA

MANNED SPACE SYSTEMS WHICH USED THE SAME LOT OF TELEDYNE

CRYSTALONICS TRANSISTORS AS THAT IN THE ORIGINAL FAILURE; LOT CODE

8619. A TOTAL OF TWENTY-SEVEN PD7400239-009/80931003731-009 LOX ULLAGE

PRESSURE TRANSDUCERS ARE AFFECTED. A TOTAL OF THIRTY PD7400239-019 LH2

ULLAGE PRESSURE TRANSDUCERS ARE AFFECTED. THE LH2 TRANSDUCERS WERE

DEVELOPED TO REPLACE THE EXISTING PD7400098-089 PARTS BUT HAVE NEVER

BEEN QUALIFIED FOR FLIGHT

TASK I. FAILURE INVESTIGATION

    A ENGINEERING IS REVIEWING THE LOX ULLAGE PRESSURE

      TRANSDUCER TEST DATA TAKEN IN MAF BLDG. 420 ON THE ETS WHICH

      HAVE THE 80931003731-009 TRANSDUCERS. THE DATA WILL BE COMPARED

      WITH THE LAST SUPPLIER CALIBRATION TESTS TO DETERMINE IF THE

      TRANSDUCERS HAVE CHANGED

      RESPONSIBILITY: L. COLON/4120--J. COOL/4120

      COMPLETE: JUNE 28, 1993

      CLOSURE STATEMENT

      SEVERAL OF THE EIGHTEEN INSTALLED AND TESTED TRANSDUCERS HAD

      MINOR CHANGES IN THE OUTPUT VOLTAGE AS COMPARED TO THE SUPPLIER

      ATP. ANY ACTIONS NECESSARY WILL BE ADDRESSED FOLLOWING THE

      COMPLETION OF THE OTHER FAILURE INVESTIGATION TASKS

   B  PURCHASING IS OBTAINING FROM TAVIS CORPORATION THE TRACEABILITY

      DATA ON THE 2N2946A TRANSISTORS USED IN ALL TRANSDUCERS OTHER

      THAN THOSE INVOLVED WITH THE SUSPECT LOT

      RESPONSIBILITY: G. PICHON/3830  M. COMBS/3830

      COMPLETE: JUNE 28, 1993

      CLOSURE STATEMENT

      TWENTY-FOUR PD7400239-009/80931003731-009 LOX ULLAGE PRESSURE

      TRANSDUCERS AND TWENTY-TWO PD7400239-019 LH2 ULLAGE PRESSURE

      TRANSDUCERS WERE IDENTIFIED WITH THE LOT CODES OF TRANSISTORS

   C  ALL PD7400239 LOX AND LH2 ULLAGE PRESSURE TRANSDUCERS IN MAF

      STORES WERE DOCUMENTED ON MARS AS BEING SUSPECT OF BEING

      INACCURATE AND WILL BE RETURNED TO TAVIS FOR TESTING. THIRTY LOX

      TRANSDUCERS WERE DOCUMENTED ON MARS T-127791. FIFTY-TWO LH2

      TRANSDUCERS WERE DOCUMENTED ON MARS T-127790

      RESPONSIBILITY: J. ADAMS/3741--D. WESTPHAL/3740

      COMPLETE: JUNE 28, 1993

   D  TESTING OF THE PD7400239 LOX AND LH2 ULLAGE PRESSURE TRANSDUCERS

      AT TAVIS WILL CONSIST OF THE POST-VIBRATION PORTION OF THE

      SUPPLIER ATP

      RESPONSIBILITY: G. PICHON/3830--M. COMBS/3830

                      L. COLON/4120--J. COOL/4120

      COMPLETE:  NOVEMBER 30, 1993

     CLOSURE STATEMENT

      1. THIRTY LOX PRESSURE TRANSDUCERS WERE TESTED AT TAVIS

         CORPORATION:

         A. TEN TRANSDUCERS WERE FOUND TO HAVE SMALL ERRORS IN OUTPUT

            VOLTAGE AND WERE DOCUMENTED ON MARS T-121303 AND T- 121304

            THE TRANSDUCERS HAVE BEEN DISPOSITIONED TO BE READJUSTED

            AND RETURNED TO MAF

         B. ONE TRANSDUCER HAD GALLED THREADS ON THE REFERENCE PORT

            FITTING, AS A RESULT OF FILTER REMOVAL FOR TESTING, AND

            WAS DOCUMENTED ON MARS T-121306. THE TRANSDUCER WAS

            DISPOSITIONED "USE-AS-IS."

         C. ONE TRANSDUCER HAD AN OUTPUT VOLTAGE ERROR SIMILAR TO THAT

            OF THE ORIGINAL FAILURE WHICH OPENED THIS CAPS. THE

            TRANSDUCER WAS DOCUMENTED ON MARS T-121302 AND

            DISPOSITIONED FOR FAILURE ANALYSIS TO BE PERFORMED; SEE

            TASK I.G. BELOW

      2. FIFTY TWO LH2 PRESSURE TRANSDUCERS WERE TESTED AT TAVIS

         CORPORATION:

         A. TWO TRANSDUCERS WERE FOUND TO HAVE SMALL ERRORS IN OUTPUT

            VOLTAGE AND WERE DOCUMENTED ON MARS T-121305.THE

            TRANSDUCERS WILL BE READJUSTED AND RETURNED TO MAF

         B. ONE TRANSDUCER HAD AN OUTPUT VOLTAGE ERROR AND WAS

            DOCUMENTED ON MARS T121307. THE MARS WAS DISPOSITIONED

            FOR FAILURE ANALYSIS; SEE TASK I.I BELOW

  E   NINETEEN TELEDYNE CRYSTALONICS TRANSISTORS FROM TAVIS STOCK ARE

      BEING TESTED TO DETERMINE THEIR CONDITION. THE TRANSISTORS ARE

      NEW UNITS WHICH HAVE BEEN UPGRADED BY TEST TO LEVEL "S" FOR

      USE IN THE PD7400239 TRANSDUCERS. EIGHTEEN OF THE TRANSISTORS

      ARE FROM THE SAME LOT CODE AS THE ORIGINAL FAILURE. THE TESTING

      IS BEING PERFORMED AT THE MARTIN MARIETTA ASTRONAUTICS GROUP IN

      DENVER, COLORADO

      RESPONSIBILITY: G. PICHON/3830--M. COMBS/3830

                      L. COLON/4120-- J. COOL/4120

      COMPLETE: AUGUST 12. 1993

      CLOSURE STATEMENT

      ALL NINETEEN TRANSISTORS PASSED THE ELECTRICAL PERFORMANCE

      TESTS. RESIDUAL GAS ANALYSIS OF FOURTEEN TRANSISTORS FOUND ONE

      UNIT THAT WAS NOT HERMETICALLY SEALED AND TWO WHICH HAD

      EXCESSIVE LEVELS OF MOISTURE. ONE OF THE TWO TRANSISTORS WITH

      EXCESSIVE MOISTURE WAS THE LOT CODE 8611 PART. THE GIDEP ALERT

      WAS REVISED TO INCLUDE THE ADDITIONAL INFORMATION AND LOT CODE;

      SEE TASK II.A

  F   ELECTRICAL ENGINEERING DEPT. 4120, WILL RECOMMEND A COURSE OF

      ACTION FOR THE TRANSDUCER PROBLEMS BASED ON AN EVALUATION OF THE

      DATA FROM THE TRANSDUCERS IN TASK I.D., THE TRANSISTORS IN

      TASK I.E., AND THE RESULTS OF THE FAILURE ANALYSES IN TASK I.G

      AND TASK I.I

      RESPONSIBILITY: G. PICHON/3830--M. COMBS/3830

                      L. COLON/4120-- J. COOL/4120

 *    COMPLETED: JANUARY 17, 1994

  CLOSURE STATEMENT

  1. REVIEW OF THE TRANSDUCER TEST DATA FROM THIRTY LOX AND FIFTY-TWO

     LH2 PRESSURE TRANSDUCERS, OBTAINED AS PART OF I.D., FOUND NO

     INDICATION OF PROBLEMS ASSOCIATED WITH AN INDIVIDUAL LOT

     OF TRANSISTORS

 *2. REVIEW OF THE TEST DATA FROM TASK I.D., FOUND THAT THE

     TRANSDUCERS HAD SMALL, BUT UNEXPECTED, CHANGES IN THE

     CALIBRATION DATA WHEN COMPARED WITH THE ORIGINAL ATP DATA. AS A

     RESULT, TEN LH2 PRESSURE TRANSDUCERS WERE SELECTED BY ELECTRICAL

     ENGINEERING TO BE TESTED FOR LONG TERM (LIFE) STABILITY OF THE

     PD7400239 DESIGN. SEE TASK I.H

 *3. THE FAILURES COVERED BY TASK I.G. AND TASK I.I. WERE THE RESULT

     OF WORKMANSHIP/QUALITY ESCAPES AND WERE JUDGED TO HAVE NO EFFECT

     ON THE OVERALL PERFORMANCE OF THE TRANSDUCERS

 G. FAILURE ANALYSIS T-121302 IS IN PROGRESS AT TAVIS CORPORATION

    THE FAILED PART IS A LOX TRANSDUCER, P/N 80931003731-009,

    S/N 0000020, AND UTILIZES TRANSISTORS WITH THE SAME LOT CODE THAT

    WAS ASSOCIATED WITH THE ORIGINAL FAILURE

    RESPONSIBILITY: G. PICHON/3830--M. COMBS/3830

                   J. ADAMS/3741--D. WESTPHAL/3740

    COMPLETE: NOVEMBER 9, 1993

    CLOSURE STATEMENT

    ANALYSIS FOUND THE CAUSE OF THE FAILURE TO BE A DEFECTIVE SOLDER

    JOINT BETWEEN A CIRCUIT BOARD TERMINAL AND ONE OF THE LEADS TO A

    DIAPHRAGM POSITION SENSING INDUCTOR. THE WIRE HAD BEEN WRAPPED

    ONTO THE TERMINAL BUT HAD NOT BEEN SOLDERED. THE MANUFACTURING

    PROCESSES INSPECT THE SOLDER JOINTS. THE DEFECT IS THE RESULT OF

    A QUALITY CONTROL ESCAPE AT TAVIS CORP

  H.AN ENGINEERING TEST PROGRAM TO DETERMINE THE LONG TERM STABILITY

    OF THE TRANSDUCERS HAS BEEN ESTABLISHED. TEN LH2 ULLAGE PRESSURE

    TRANSDUCERS, PART NUMBER PD7400239-019, WERE SELECTED BY

    ENGINEERING FROM AMONG THE FIFTY-TWO PARTS NOW EXISTING. THE

    TRANSDUCERS ARE TO BE TESTED FOR ACCURACY AT 90 DAY INTERVALS

    UNTIL THE FIRST FLIGHT OF AN ET WITH PD7400239-009 TRANSDUCERS

    THEREAFTER, THE TEN TRANSDUCERS WILL BE TESTED AT 180 DAY

    INTERVALS UNTIL THE PARTS ARE FIVE YEARS OLD (I.E. DECEMBER 1996)

    THE TESTING IS CONTROLLED BY OPERATIONS DIRECTIVE 93-OD-0643

 I. A PD7400239-019 LH2 ULLAGE PRESSURE TRANSDUCER, SERIAL NUMBER

    0000065, FAILED THE TESTS AT TAVIS CORP DOCUMENTED IN TASK I.D

    THE TRANSDUCER OUTPUT WAS 676MV REGARDLESS OF APPLIED PRESSURE,

    AT AN OPERATING TEMPERATURE OF 150 DEGREES FAHRENHEIT. THE

    TRANSDUCER WILL BE DOCUMENTED ON MARS T-121307 AND DISPOSITIONED

    FOR FAILURE ANALYSIS

        RESPONSIBILITY: G. PICHON/3830--M. COMBS/3830

                        J. ADAMS/3741--D. WESTPHAL/3740

  *     COMPLETE: JANUARY 17, 1994

  * CLOSURE STATEMENT

    ANALYSIS FOUND THAT THE INSULATION ON A WIRE HAD BEEN DAMAGED AND

    WAS CAUSING A SHORT CIRCUIT BETWEEN TRANSDUCER COMPONENTS. THE

    DAMAGE WAS THE RESULT OF A WORKMANSHIP/QUALITY ESCAPE WHICH

    IMPROPERLY POSITIONED THE WIRE IN THE ASSEMBLY

    TASK CLOSED

CAUSE

ORIGINAL FAILURE - THE TRANSISTOR WAS DEFECTIVE AS SUPPLIED FROM THE

                   MANUFACTURER

PROBLEMS DISCOVERED DURING THE TASK I INVESTIGATION - SEE TASK II

                   CORRECTIVE ACTION FOR DETAILS

TASK II. CORRECTIVE ACTION

  A. THE CORRECTIVE ACTIONS FOR THE DEFECTIVE TRANSISTORS ARE LISTED

     BELOW. REVIEW BY ELECTRICAL ENGINEERING, TASK I,F.1., DID NOT

     RECOMMEND FURTHER ACTIONS

     1. GIDEP ALERT 9Q-A-93-03 WAS ORIGINALLY RELEASED BY THE GIDEP

        SYSTEM AND WAS BASED ON THE SINGLE ORIGINAL DEFECTIVE

        TRANSISTOR. THE ALERT WAS SUBSEQUENTLY REVISED TO 9Q-A-93-03A

        TO INCLUDE INFORMATION ON OTHER FAILURES DISCOVERED AS PART OF

        TASK I.E

        RESPONSIBILITY: B. CORNAY/3742  D. WESTPHAL/3740

        COMPLETE: SEPTEMBER 9, 1993

     2. SCAD 92-132 WAS ISSUED TO TAVIS CORP

        RESPONSIBILITY: T. PASTORET/3742--D. WESTPHAL/3740

        COMPLETE: JULY 29, 1993

 *B.   CORRECTIVE ACTION FOR THE CHANGES IN THE TRANSDUCER

       CALIBRATIONS, IDENTIFIED DURING ELECTRICAL ENGINEERING REVIEW

       OF TEST DATA IN TASK I.F.2., WAS ADDRESSED BY INSTITUTING A

       LONG TERM TEST OF TRANSDUCER PERFORMANCE. REFERENCE: TASK I.H

       AND OPERATION DIRECTIVE 93-OD-0643. SHOULD THE TEST RESULTS

       INDICATE THAT FURTHER ACTION IS NECESSARY, IT WILL BE ADDRESSED

       BY ENGINEERING CHANGES

 *C.   CORRECTIVE ACTIONS FOR THE FAILURE CAUSED BY A WIRE CONNECTION

       WHICH HAD NOT BEEN SOLDERED WERE TO REVISE THE SOLDER

       INSPECTION CRITERIA OF THE MANUFACTURING TRAVELERS AT THE

       APPLICABLE STAGE OF ASSEMBLY. REFERENCE: TAVIS CORPORATION

       TEST TRAVELER 10345-1, STEP 340, FOR THE

       PD7400239-009; AND TAVIS CORPORATION PRODUCTION TEST TRAVELER

       10346-1, STEP 330, FOR THE PD7400239-019

  *D   CORRECTIVE ACTIONS FOR THE FAILURE CAUSED BY DAMAGED WIRE

       INSULATION WERE TO REVISE THE MANUFACTURING TRAVELERS,

       ENGINEERING DRAWINGS, AND TO CREATE A TOOL TO CONTROL THE

       ASSEMBLY AND PREVENT NICKED WIRES

       1. PD7400239-009 LOX TRANSDUCER; TAVIS CORPORATION PRODUCTION

          TEST TRAVELER 10345-1, STEP 240, ALIGNMENT TOOL #T0215;

          TAVIS CORPORATION PRODUCTION TEST TRAVELER 10345-1, STEP

          350, WIRE ROUTING; AND TAVIS CORPORATION ENGINEERING DRAWING

          18131, REVISION C., DOCUMENTATION ACCOUNTABILITY SHEET (DAS)

          BBE-061

       2. PD7400239-019 LH2 TRANSDUCER: TAVIS CORPORATION PRODUCTION

          TEST TRAVELER 10346-1, STEP 230, ALIGNMENT TOO #T0215; TAVIS

          CORPORATION PRODUCTION TEST TRAVELER 10346-1, STEP 340, WIRE

          ROUTING; AND TAVIS CORPORATION ENGINEERING DRAWING 18913,

          REVISION B., DOCUMENTATION ACCOUNTABILITY SHEET (DAS) BBG-056

TASK CLOSED

TASK III. CLEARANCE OF EFFECTIVITIES

 ALL ETS CLEARED. TESTING OF THE EIGHTY-TWO PD7400239 TRANSDUCERS, NOT

 INSTALLED ON ETS, FOUND NO INDICATION OF A TRANSISTOR LOT RELATED

 PROBLEM.  REVIEW OF THE TEST DATA FROM TRANSDUCERS INSTALLED ON ETS

 FOUND NO INDICATION OF A TRANSISTOR LOT RELATED PROBLEM. REVIEW OF

 THE TEST DATA FROM TRANSDUCERS INSTALLED ON ETS FOUND NO INDICATION

 OF A TRANSISTOR LOT RELATED PROBLEM. THERE ARE SUFFICIENT TESTS OF

 TRANSDUCER PERFORMANCE AT THE SUPPLIER, MAF, AND KSC TO ASSURE

 PERFORMANCE DURING PROPELLANT LOADING AND FLIGHT

 ETS 64 AND SUBSEQUENT HAVE THREE ACTIVE PD7400239-009 LOX ULLAGE

 PRESSURE TRANSDUCERS CONNECTED TO THE ORBITER AT A TIME. THE LAUNCH

 COMMIT CRITERIA (LSS) REQUIRES THAT TWO OF THE THREE BE FUNCTIONING

 THROUGH THE PRE-PRESS EVENT OF PROPELLANT LOADING.  NONE ARE

 REQUIRED FOR FLIGHT

TASK CLOSED

*TASK IV. CAPS CLOSURE SUMMARY

A FAILURE OF A PD7400239 LOX ULLAGE PRESSURE TRANSDUCER WAS TRACED TO

A DEFECTIVE TRANSISTOR. A GIDEP ALERT WAS ISSUED AGAINST THE

TRANSISTOR LOT AND WAS BACKED BY TESTS OF OTHER TRANSISTORS FROM THE

SAME LOT. THE MAF TEST DATA FOR ALL INSTALLED TRANSDUCERS WAS REVIEWED

ALONG WITH TEST DATA OBTAINED BY RETURNING ALL UNINSTALLED PARTS TO

THE SUPPLIER FOR CALIBRATION TESTING. NO DEFINITE LINK COULD BE FOUND

BETWEEN THE TRANSISTOR LOTS AND THE PERFORMANCE OF THE COMPLETED

TRANSDUCERS

DURING THE INVESTIGATION ASSOCIATED WITH THE FIRST FAILURE, THREE

OTHER PROBLEMS OCCURRED. THE FIRST WAS CALIBRATION SHIFTS NOTED IN THE

TRANSDUCERS RETURNED TO THE SUPPLIER. AS A RESULT OF SHIFTS, A LONG

TERM TEST HAS BEEN INITIATED TO VERIFY TRANSDUCER STABILITY. THE

SECOND AND THIRD PROBLEMS WERE TWO SEPARATE TRANSDUCER FAILURES

RESULTING FROM WORKMANSHIP ESCAPES DURING TRANSDUCER MANUFACTURE

THESE FAILURES WERE ADDRESSED BY PLACING ADDITIONAL CONTROLS IN THE

SUPPLIERS MANUFACTURING TRAVELERS AND DRAWINGS

TASK CLOSED

THIS CAPS IS CLOSED. NO FURTHER ACTION IS REQUIRED

MSFC Response/Concurrence

MSFC Problem Reporting and Corrective Action (PRACA) System

ASSESSMENT ADDENDUM REPORT

MSFC Report#
A15483

IFA#
--

Contractor RPT#
E-152

JSC#
--

KSC#
--

EICN#
--

Asmnt Part#
80931003731-009

Asmnt Part Name
LOX PRES TRANSDUCER

Asmnt Serial/Lot#
0000028

HCRIT CD
--

FCRIT CD
3

CAUSE CD
MAW - MFG-ASY-WORK

FAIL MODE
EG - SIG HI OR LO

Asmnt FMEA
3.2.1.1C

Asmnt FM
1C

FMEA CSE
E

FMEA SCSE
4

Asmnt FMEA
--

Asmnt FM
--

FMEA CSE
--

FMEA SCSE
--

Asmnt FMEA
--

Asmnt FM
--

FMEA CSE
--

FMEA SCSE
--

Correlated Part#
--

Correlated Part#
--

Correlated Part#
--

Associated LRU#
--

Associated LRU#
--

Associated LRU#
--

MAJOR DESIGN CHANGES

APRV DATE
--

DESCRIPTION OF CHANGES
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ASSESSMENT TEXT