Narrative:

During a scheduled line check, the caution light modules #8 and #9 had unreadable legends. The modules were removed and replaced with the wrong part number modules, thus changing the segment confign. The aircraft was modified with a rudder isolation valve and part of the modification is to change a 'filter' in the caution panel module and inscribe a new part number on the side of the module, the old number is to be crossed out. When I removed the discrepant modules I used the part number on the side of the module (which should have been crossed out and a new one installed). This failure to change the number, and my neglect in consulting the ipc (illustrated parts catalog) resulted in the wrong module being installed in position #8 and #9. The aircraft was released for passenger service and flew for several days, until the aircraft encountered a loss of hydraulic pressure on the #1 system. This resulted in the 'rudder isolation valve' being activated. The caution light was illuminated, and instead of the 'rudder isolation valve' caution light being illuminated it was a blank (only a lighted dash in the segment).

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Original NASA ASRS Text

Title: A DHC8-100 WAS DISPATCHED IN NON COMPLIANCE WITH THE INCORRECT MASTER CAUTION ANNUNCIATOR PANEL INSTALLED CAUSED BY A SHOP PART NUMBER ERROR.

Narrative: DURING A SCHEDULED LINE CHK, THE CAUTION LIGHT MODULES #8 AND #9 HAD UNREADABLE LEGENDS. THE MODULES WERE REMOVED AND REPLACED WITH THE WRONG PART NUMBER MODULES, THUS CHANGING THE SEGMENT CONFIGN. THE ACFT WAS MODIFIED WITH A RUDDER ISOLATION VALVE AND PART OF THE MODIFICATION IS TO CHANGE A 'FILTER' IN THE CAUTION PANEL MODULE AND INSCRIBE A NEW PART NUMBER ON THE SIDE OF THE MODULE, THE OLD NUMBER IS TO BE CROSSED OUT. WHEN I REMOVED THE DISCREPANT MODULES I USED THE PART NUMBER ON THE SIDE OF THE MODULE (WHICH SHOULD HAVE BEEN CROSSED OUT AND A NEW ONE INSTALLED). THIS FAILURE TO CHANGE THE NUMBER, AND MY NEGLECT IN CONSULTING THE IPC (ILLUSTRATED PARTS CATALOG) RESULTED IN THE WRONG MODULE BEING INSTALLED IN POS #8 AND #9. THE ACFT WAS RELEASED FOR PAX SVC AND FLEW FOR SEVERAL DAYS, UNTIL THE ACFT ENCOUNTERED A LOSS OF HYD PRESSURE ON THE #1 SYS. THIS RESULTED IN THE 'RUDDER ISOLATION VALVE' BEING ACTIVATED. THE CAUTION LIGHT WAS ILLUMINATED, AND INSTEAD OF THE 'RUDDER ISOLATION VALVE' CAUTION LIGHT BEING ILLUMINATED IT WAS A BLANK (ONLY A LIGHTED DASH IN THE SEGMENT).

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.