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).