A TECHNICIAN RPTS DEHAVILLAND -100 HORIZ STABILIZER REPAIR DOUBLERS FOR TOP AND BOTTOM WERE FABRICATED WITH IMPROPER MATERIAL.

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ABOUT 3 YRS AGO DHC HAD PROBS WITH DELAMINATION ON THE HORIZ STABILIZERS ON SOME ACFT. THE OPERATORS HAD TO CUT SAMPLES FROM THE TOP AND BOTTOM OF THE HORIZ STABILIZERS AND SEND THEM TO DEHAVILLAND FOR TESTING. THEN REPAIR DOUBLERS MADE FROM 2024T3 ALUMINUM WERE INSTALLED OVER THE CUTOUTS. AT FIRST ONLY A FEW AIRPLANES NEEDED TO BE DONE AND THE DOUBLERS WERE FABRICATED IN HOUSE AS NEEDED. THEN LATER ON DHC WANTED MORE ACFT TESTED. DUE TO THE NUMBER OF ACFT BEING TESTED; ACR HAD AN OUTSIDE VENDOR FABRICATE THE REPAIR DOUBLERS. THIS VENDOR DID NOT HAVE AN A&P LICENSE AND COULD NOT SIGN FOR HIS WORK ON THE MANUFACTURER SHEETS. TO MY KNOWLEDGE ACR SUPPLIED MATERIALS FOR THE WORK. THE PARTS WERE SENT THROUGH THE SHEET METAL SHOP AND MECHS WERE TOLD TO INSPECT AND SIGN FOR MANUFACTURER OF THE PARTS. I DON'T REMEMBER IF I SIGNED FOR THE FABRICATION OF THE PARTS THAT MADE IT INTO THE PARTS ROOM. I DO REMEMBER REJECTING SOME THAT WERE MADE DUE TO WRONG SIZE PLT HOLES. ON JUL/WED/03 I WAS TOLD THAT IT WAS DISCOVERED THAT SOME OF THOSE PARTS WERE MADE FROM 2024T0 INSTEAD OF T3. ACR HAS NOTIFIED THE FAA AND DHC. AS FAR AS I KNOW RIGHT NOW THE AFFECTED PARTS HAVE BEEN REMOVED FROM STORES AND ARE BEING REMOVED FROM THE AFFECTED ACFT.