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A B737-500 had 2 technicians troubleshoot a previously deferred engine driven generator system. After troubleshooting; the unit went out deferred. Later had external failure.
| Attributes | |
| ACN | 675827 |
| Time | |
| Date | 200510 |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-500 |
| Operating Under FAR Part | Part 121 |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : lead technician maintenance : technician |
| Qualification | technician : airframe technician : powerplant |
| Experience | maintenance lead technician : 12 maintenance technician : 8 |
| ASRS Report | 675827 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : powerplant technician : airframe |
| Experience | maintenance technician : 17 |
| ASRS Report | 675830 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : far non adherence : published procedure |
| Independent Detector | other other : 3 |
| Resolutory Action | none taken : detected after the fact |
| Factors | |
| Maintenance | contributing factor : lighting contributing factor : weather performance deficiency : fault isolation performance deficiency : scheduled maintenance performance deficiency : unqualified personnel performance deficiency : repair |
| Supplementary | |
| Problem Areas | Aircraft Maintenance Human Performance |
| Primary Problem | Maintenance Human Performance |
Narrative:
I was notified by my supervisor on oct/tue/05 that aircraft X CSD/generator had an external failure. I had performed troubleshooting on this system on oct/sun/05. During troubleshooting; the engine was run 3 times. The fist time we reconnected the CSD and installed a new gcu. (When reconnecting CSD; it did not feel right; no resistance when t-handle pulled.) upon start; there was no indication of volts or frequencys. Engine was shut down and we rechked that the CSD was connected. The second time the engine was run; we had same results. Engine was shut down and we reinstalled original gcu. We then checked wiring and firewall connector plug -- no problems found. The third time we ran engine; we still had no volts or frequencys; I disconnected CSD per MEL procedures. Low pressure light illuminated and no residual volts present. Engine was then shut down. I removed lamps from indicator light per procedure; as they were not previously removed. All troubleshooting was done with reference to amm.
Original NASA ASRS Text
Title: A B737-500 HAD 2 TECHNICIANS TROUBLESHOOT A PREVIOUSLY DEFERRED ENG DRIVEN GENERATOR SYS. AFTER TROUBLESHOOTING; THE UNIT WENT OUT DEFERRED. LATER HAD EXTERNAL FAILURE.
Narrative: I WAS NOTIFIED BY MY SUPVR ON OCT/TUE/05 THAT ACFT X CSD/GENERATOR HAD AN EXTERNAL FAILURE. I HAD PERFORMED TROUBLESHOOTING ON THIS SYS ON OCT/SUN/05. DURING TROUBLESHOOTING; THE ENG WAS RUN 3 TIMES. THE FIST TIME WE RECONNECTED THE CSD AND INSTALLED A NEW GCU. (WHEN RECONNECTING CSD; IT DID NOT FEEL RIGHT; NO RESISTANCE WHEN T-HANDLE PULLED.) UPON START; THERE WAS NO INDICATION OF VOLTS OR FREQS. ENG WAS SHUT DOWN AND WE RECHKED THAT THE CSD WAS CONNECTED. THE SECOND TIME THE ENG WAS RUN; WE HAD SAME RESULTS. ENG WAS SHUT DOWN AND WE REINSTALLED ORIGINAL GCU. WE THEN CHKED WIRING AND FIREWALL CONNECTOR PLUG -- NO PROBS FOUND. THE THIRD TIME WE RAN ENG; WE STILL HAD NO VOLTS OR FREQS; I DISCONNECTED CSD PER MEL PROCS. LOW PRESSURE LIGHT ILLUMINATED AND NO RESIDUAL VOLTS PRESENT. ENG WAS THEN SHUT DOWN. I REMOVED LAMPS FROM INDICATOR LIGHT PER PROC; AS THEY WERE NOT PREVIOUSLY REMOVED. ALL TROUBLESHOOTING WAS DONE WITH REFERENCE TO AMM.
Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.