Narrative:

I was removing the forward entry door upper hinge box and the drain fitting was double flush riveted and I couldn't see the rivets; so I tried to drill the last hiloc securing the box out; with a 12 inch drill bit and curve it past the drain fitting. I didn't realize I had slipped off of the hiloc rivet until I stopped to check my drill bit's progress. When I saw I had slipped off the hiloc and drilled the box; I ground the hiloc head off and punched the shank out. It wasn't until I had removed the box that I saw I had drilled through the hinge box and into aircraft structure. I immediately told my supervisor and manager.

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Original NASA ASRS Text

Title: WHILE REMOVING THE FORWARD ENTRY DOOR UPPER HINGE BOX ON A B737-300 ACFT; MECHANIC INADVERTENTLY DRILLS THROUGH THE BOX SECTION AND INTO THE DOOR CUTOUT FRAME STRUCTURE.

Narrative: I WAS REMOVING THE FORWARD ENTRY DOOR UPPER HINGE BOX AND THE DRAIN FITTING WAS DOUBLE FLUSH RIVETED AND I COULDN'T SEE THE RIVETS; SO I TRIED TO DRILL THE LAST HILOC SECURING THE BOX OUT; WITH A 12 INCH DRILL BIT AND CURVE IT PAST THE DRAIN FITTING. I DIDN'T REALIZE I HAD SLIPPED OFF OF THE HILOC RIVET UNTIL I STOPPED TO CHK MY DRILL BIT'S PROGRESS. WHEN I SAW I HAD SLIPPED OFF THE HILOC AND DRILLED THE BOX; I GROUND THE HILOC HEAD OFF AND PUNCHED THE SHANK OUT. IT WASN'T UNTIL I HAD REMOVED THE BOX THAT I SAW I HAD DRILLED THROUGH THE HINGE BOX AND INTO ACFT STRUCTURE. I IMMEDIATELY TOLD MY SUPVR AND MGR.

Data retrieved from NASA's ASRS site as of May 2009 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.