Narrative:

On preflight, the flight crew noticed a dent on #6 leading edge slat. The captain called dispatch whom then conferenced me into the conversation. The captain said he had notified maintenance that he thought the #6 leading edge slat had been struck by something on the ground. A mechanic told the captain, then got on the phone telling me that the dent was caused by a bird or something of that nature. There was a 'slime' type substance around the dent. The mechanic said that he would call me back with measurements so we could review the structural repair manual limits together and perform a bird strike inspection. One mechanic called me from the jetbridge phone while another mechanic was taking the measurement on the leading edge slat communicating with us via operations radio that each mechanic carries. While on the phone, a third mechanic called over operations radio reading the measurements from the dent log regarding the dent on the #3 leading edge slat. The initial thought was the wrong slat number was entered into the dent log. The thought was that this dent should have been the #6 leading edge slat instead of the #3 leading edge slat since the initial measurements were so close. We concluded, that because of the 'slime,' this was a different dent and proceeded with the inspection. The mechanic taking the dent measurement, I think, was having a bit of difficulty obtaining the measurements due to ground equipment movement. He gave a set of measurements and while I was running the X/Y ratio, he called back with a set of measurements just slightly different. I ran the X/Y ratio and came to the conclusion that the dent was within structural repair manual limits for no further inspection. I asked the mechanic on the phone 2 more separate times, for the measurements to be taken again. This was done to be sure all 3 measurements were the same. All 3 times the measurements came back 5.5 inches long by 2 inches wide by .090 inch deep. A/Y ratio = 22.222. I then instructed the mechanics to enter the measurements into the book along with the X/Y ratio and the bird strike inspection. We are good to go. The next day on a thru-flight through XXX, the plane was pulled from service to replace the 36 leading edge slat because the dent was bigger than the original measurements taken in. After reviewing the log entry, I requested of the mechanics and the structural repair manual, I have concluded that I made an unintentional mistake. The match computations were correct but, I just realized, as I went back and forth through the structural repair manual pages I had in my mind and kept reading that the structural repair manual X/Y ratio stated 'X/Y must be less than 30 inches.' for some reason during the whole process, my mind was blocking out the 'not.' I believe that the mechanics did nothing incorrectly. Because the structural repair manual can be very difficult to work with, they depended upon my guidance. I made a mistake, the fault rests upon me.

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Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED IN NON COMPLIANCE WITH A LEADING EDGE SLAT DENT THAT WAS OUT OF STRUCTURAL REPAIR MANUAL LIMITS.

Narrative: ON PREFLT, THE FLC NOTICED A DENT ON #6 LEADING EDGE SLAT. THE CAPT CALLED DISPATCH WHOM THEN CONFERENCED ME INTO THE CONVERSATION. THE CAPT SAID HE HAD NOTIFIED MAINT THAT HE THOUGHT THE #6 LEADING EDGE SLAT HAD BEEN STRUCK BY SOMETHING ON THE GND. A MECH TOLD THE CAPT, THEN GOT ON THE PHONE TELLING ME THAT THE DENT WAS CAUSED BY A BIRD OR SOMETHING OF THAT NATURE. THERE WAS A 'SLIME' TYPE SUBSTANCE AROUND THE DENT. THE MECH SAID THAT HE WOULD CALL ME BACK WITH MEASUREMENTS SO WE COULD REVIEW THE STRUCTURAL REPAIR MANUAL LIMITS TOGETHER AND PERFORM A BIRD STRIKE INSPECTION. ONE MECH CALLED ME FROM THE JETBRIDGE PHONE WHILE ANOTHER MECH WAS TAKING THE MEASUREMENT ON THE LEADING EDGE SLAT COMMUNICATING WITH US VIA OPS RADIO THAT EACH MECH CARRIES. WHILE ON THE PHONE, A THIRD MECH CALLED OVER OPS RADIO READING THE MEASUREMENTS FROM THE DENT LOG REGARDING THE DENT ON THE #3 LEADING EDGE SLAT. THE INITIAL THOUGHT WAS THE WRONG SLAT NUMBER WAS ENTERED INTO THE DENT LOG. THE THOUGHT WAS THAT THIS DENT SHOULD HAVE BEEN THE #6 LEADING EDGE SLAT INSTEAD OF THE #3 LEADING EDGE SLAT SINCE THE INITIAL MEASUREMENTS WERE SO CLOSE. WE CONCLUDED, THAT BECAUSE OF THE 'SLIME,' THIS WAS A DIFFERENT DENT AND PROCEEDED WITH THE INSPECTION. THE MECH TAKING THE DENT MEASUREMENT, I THINK, WAS HAVING A BIT OF DIFFICULTY OBTAINING THE MEASUREMENTS DUE TO GND EQUIP MOVEMENT. HE GAVE A SET OF MEASUREMENTS AND WHILE I WAS RUNNING THE X/Y RATIO, HE CALLED BACK WITH A SET OF MEASUREMENTS JUST SLIGHTLY DIFFERENT. I RAN THE X/Y RATIO AND CAME TO THE CONCLUSION THAT THE DENT WAS WITHIN STRUCTURAL REPAIR MANUAL LIMITS FOR NO FURTHER INSPECTION. I ASKED THE MECH ON THE PHONE 2 MORE SEPARATE TIMES, FOR THE MEASUREMENTS TO BE TAKEN AGAIN. THIS WAS DONE TO BE SURE ALL 3 MEASUREMENTS WERE THE SAME. ALL 3 TIMES THE MEASUREMENTS CAME BACK 5.5 INCHES LONG BY 2 INCHES WIDE BY .090 INCH DEEP. A/Y RATIO = 22.222. I THEN INSTRUCTED THE MECHS TO ENTER THE MEASUREMENTS INTO THE BOOK ALONG WITH THE X/Y RATIO AND THE BIRD STRIKE INSPECTION. WE ARE GOOD TO GO. THE NEXT DAY ON A THRU-FLT THROUGH XXX, THE PLANE WAS PULLED FROM SVC TO REPLACE THE 36 LEADING EDGE SLAT BECAUSE THE DENT WAS BIGGER THAN THE ORIGINAL MEASUREMENTS TAKEN IN. AFTER REVIEWING THE LOG ENTRY, I REQUESTED OF THE MECHS AND THE STRUCTURAL REPAIR MANUAL, I HAVE CONCLUDED THAT I MADE AN UNINTENTIONAL MISTAKE. THE MATCH COMPUTATIONS WERE CORRECT BUT, I JUST REALIZED, AS I WENT BACK AND FORTH THROUGH THE STRUCTURAL REPAIR MANUAL PAGES I HAD IN MY MIND AND KEPT READING THAT THE STRUCTURAL REPAIR MANUAL X/Y RATIO STATED 'X/Y MUST BE LESS THAN 30 INCHES.' FOR SOME REASON DURING THE WHOLE PROCESS, MY MIND WAS BLOCKING OUT THE 'NOT.' I BELIEVE THAT THE MECHS DID NOTHING INCORRECTLY. BECAUSE THE STRUCTURAL REPAIR MANUAL CAN BE VERY DIFFICULT TO WORK WITH, THEY DEPENDED UPON MY GUIDANCE. I MADE A MISTAKE, THE FAULT RESTS UPON ME.

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.