A B737-300 WAS DISPATCHED IN NON COMPLIANCE WITH AN IMPROPER INTERIM REPAIR MADE TO #1 LEADING EDGE SLAT CAUSED BY REPAIR MANUAL DEFICIENCY.

Narrative

I WAS ACCOMPLISHING A ROUTINE WALKAROUND AFTER RECEIVING AN ACFT ON MY GATE. I FOUND A 2 INCH CRACK ON #1 SLAT LOWER SKIN IN THE AREA OF ACTUATOR ATTACH POINT. I CALLED MY LEAD AND MAINT OPS CTR TO TELL OF MY FINDING AND TO LOOK FOR DIRECTION ON WHAT APCH TO TAKE. WE FIGURED IT WAS A 'NO-GO' ITEM. WE RESEARCHED OUR TYPICAL REPAIR MANUAL FOR A REF OR DIRECTIONS ON A REPAIR. MAINT OPS CTR AND MY LEAD FOUND NOTHING. OUR TWR FORMAN OR CLT OPS FORMAN ON DUTY; NOT MAINT OPS CTR; THOUGHT THERE WAS A TYPICAL REPAIR MANUAL. MY LEAD LOOKED AGAIN BUT COULD NOT FIND ANYTHING. I CALLED OUR LINE ENGINEERING DEPT. THE ENGINEER GAVE US A STRUCTURAL REPAIR MANUAL REF TO USE; AND SAID TO 'STOP DRILL AS INDICATED IN THE STRUCTURAL REPAIR MANUAL.' THE ENGINEER DID NOT GIVE ANY CAUTIONS. I DID ASK WHAT SIZE AND PROPER PROC FOR STOP DRILLING. THE STRUCTURAL REPAIR MANUAL 57-43-01 FIGURE 101 SAID TO STOP DRILL AND RELEASE ACFT WITH REQUIRED REINSPECTIONS AND FINAL REPAIRS AS INDICATED. I STOPPED DRILLING AS INDICATED BY MARKS LEFT BY NON DESTRUCTIVE TESTING INSPECTOR. WE THEN SIGNED OFF THE LOGBOOK AS OPEN; CREATED A ROUTINE OVERNIGHT LAYOVER FOR REINSPECTION/FINAL REPAIR; AND CREATED AN ITEM IN THE DAMAGE FILE (AN ONBOARD RECORD KEPT IN LOGBOOK). THE ACFT LEFT. I TOLD A CO-WORKER WHAT TRANSPIRED; AND HE MENTIONED THAT THERE USED TO BE A TYPICAL REPAIR MANUAL BUT IT WAS REMOVED. IT USED TO HAVE A CAUTION 'WHEN STOP DRILLING; BE CAREFUL NOT TO DAMAGE OR GO THROUGH THE 'T' CORD BEHIND THE SKIN' IF YOU STOP DRILLED. THE STRUCTURAL REPAIR MANUAL DID NOT SAY THIS. I TOLD MY CO-WORKER THAT I DRILLED THROUGH THE SKIN AND THE 'T' CORD. HE SAID 'THAT MAY BE AN ISSUE' AND THAT 'HOW COULD YOU KNOW NOT TO; IF IT WASN'T WRITTEN IN THE INSTRUCTIONS?' I BECAME CONCERNED; SO I CALLED THE ENGINEER AND STOPPED; LATE AFTER WORK; TO TALK TO HIM. LETTING HIM KNOW MY CONCERNS. HE SAID 'IT WILL PROBABLY BE OK;' 'BUT HE WOULD INVESTIGATE.' I FOUND OUT 2-4 DAYS AFTER; FROM OUR FLT SAFETY REPRESENTATIVE; THAT THE ACFT WAS STOPPED AT ITS NEXT LNDG (WHICH WAS TO BE A ROUTINE OVERNIGHT LAYOVER) AND THEN WAS MAINT FERRIED TO A BASE FOR REPAIRS. AS IT SEEMS; THE STOP DRILLING WAS NOT TO BE INTO THE 'T' CORD; AND OUR COMPANY MADE A SELF DISCLOSURE TO THE FAA.