Narrative:

I was accomplishing a routine walkaround after receiving an aircraft 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 maintenance operations center to tell of my finding and to look for direction on what approach to take. We figured it was a 'no-go' item. We researched our typical repair manual for a reference or directions on a repair. Maintenance operations center and my lead found nothing. Our tower forman or clt operations forman on duty, not maintenance operations center, thought there was a typical repair manual. My lead looked again but could not find anything. I called our line engineering department. The engineer gave us a structural repair manual reference 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 procedure for stop drilling. The structural repair manual 57-43-01 figure 101 said to stop drill and release aircraft 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 aircraft 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 flight safety representative, that the aircraft was stopped at its next landing (which was to be a routine overnight layover) and then was maintenance 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.

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Original NASA ASRS Text

Title: 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.

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.