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A DC9-10 PA relay interlock box was found to be wired for one airplane only but had no wiring diagrams or support documentation.
| Attributes | |
| ACN | 563834 |
| Time | |
| Date | 200210 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 10 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| Qualification | technician : fcc technician : airframe technician : powerplant |
| Experience | maintenance avionics : 9 |
| ASRS Report | 563834 |
| Person 2 | |
| Affiliation | other |
| Function | other personnel other |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper documentation non adherence : published procedure non adherence : far |
| Independent Detector | other other : person 1 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : non availability of parts contributing factor : manuals contributing factor : engineering procedure performance deficiency : non compliance with legal requirements performance deficiency : repair performance deficiency : testing performance deficiency : installation performance deficiency : logbook entry |
| Supplementary | |
| Problem Areas | Aircraft Chart Or Publication Company Maintenance Human Performance |
| Primary Problem | Chart Or Publication |
| Situations | |
| Publication | WIRING DIAGRAM MANUAL |
Narrative:
On oct/thu/02, a PA interlock relay box was removed and replaced for a chime problem, on aircraft X. After relay box was changed, a different problem began. PA did not operate from any station in the cockpit, but it worked at the forward and aft attendant panel stations. Troubleshooting began for several days, including changing the relay box again, changing wires out, inspecting everything and anything. Finally, original interlock relay box was found to be uniquely wired just for aircraft X. All of this was done by several different technicians on rotating shifts. Original relay box was received on oct/fri/02 and installed, but the problem did not go away. It was discovered by myself and company X engineering that original box was changed. Vendors apparently using wrong wiring maintenance manuals, provided by company X, changed internal wiring. Therefore, when we received original relay box, it acted like any other new box. I knew what the problem was so, therefore, using component wiring manuals I opened the box and wired relay box to original condition using component maintenance manual (supplemental 23-30-2 dated oct/xa/02). I installed the box and performed a system functional check using maintenance manual.
Original NASA ASRS Text
Title: A DC9-10 PA RELAY INTERLOCK BOX WAS FOUND TO BE WIRED FOR ONE AIRPLANE ONLY BUT HAD NO WIRING DIAGRAMS OR SUPPORT DOCUMENTATION.
Narrative: ON OCT/THU/02, A PA INTERLOCK RELAY BOX WAS REMOVED AND REPLACED FOR A CHIME PROB, ON ACFT X. AFTER RELAY BOX WAS CHANGED, A DIFFERENT PROB BEGAN. PA DID NOT OPERATE FROM ANY STATION IN THE COCKPIT, BUT IT WORKED AT THE FORWARD AND AFT ATTENDANT PANEL STATIONS. TROUBLESHOOTING BEGAN FOR SEVERAL DAYS, INCLUDING CHANGING THE RELAY BOX AGAIN, CHANGING WIRES OUT, INSPECTING EVERYTHING AND ANYTHING. FINALLY, ORIGINAL INTERLOCK RELAY BOX WAS FOUND TO BE UNIQUELY WIRED JUST FOR ACFT X. ALL OF THIS WAS DONE BY SEVERAL DIFFERENT TECHNICIANS ON ROTATING SHIFTS. ORIGINAL RELAY BOX WAS RECEIVED ON OCT/FRI/02 AND INSTALLED, BUT THE PROB DID NOT GO AWAY. IT WAS DISCOVERED BY MYSELF AND COMPANY X ENGINEERING THAT ORIGINAL BOX WAS CHANGED. VENDORS APPARENTLY USING WRONG WIRING MAINT MANUALS, PROVIDED BY COMPANY X, CHANGED INTERNAL WIRING. THEREFORE, WHEN WE RECEIVED ORIGINAL RELAY BOX, IT ACTED LIKE ANY OTHER NEW BOX. I KNEW WHAT THE PROB WAS SO, THEREFORE, USING COMPONENT WIRING MANUALS I OPENED THE BOX AND WIRED RELAY BOX TO ORIGINAL CONDITION USING COMPONENT MAINT MANUAL (SUPPLEMENTAL 23-30-2 DATED OCT/XA/02). I INSTALLED THE BOX AND PERFORMED A SYS FUNCTIONAL CHK USING MAINT MANUAL.
Data retrieved from NASA's ASRS site as of July 2007 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.