AN ACFT INSPECTOR REPORTS ON ISSUES SURROUNDING RESPONSIBILITIES BASED ON MAINT SIGNOFFS; INVOLVING A B737-300 FUSELAGE SKIN REPAIR; THAT WAS REMOVED AND NEW REPAIR INSTALLED WITH IMPROPER ENGINEERING AUTHORITY.

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A FUSELAGE SKIN REPAIR WAS REMOVED AND A NEW REPAIR WAS INSTALLED STA 727 15 STRINGER 14R WITH AN IMPROPER ENGINEERING AUTH. I WAS INVOLVED IN THE LAST 2 INSPECTION BUY-OFFS PERTAINING TO 1) REINSTALLING AN INTERIOR SIDEWALL; AND 2) MAKING SURE THE NON-ROUTINE CARD WAS SIGNED OFF PER THAT ENGINEERING AUTH. THIS REPAIR WAS COMPLETELY FINISHED AND INSTALLED AND BOUGHT OFF BY OTHER MECHS AND INSPECTION BEFORE I WAS INVOLVED. I FEEL THAT BECAUSE MY STAMP WAS THE LAST ONE INVOLVED THE LETTER OF INVESTIGATION CAME TO ME. WHEN WE FOLLOW REPAIR INSTRUCTIONS FROM AN ENGINEERING AUTH THAT ENGINEERING GIVES US; IT IS A MULTI-STEP SIGN-OFF PROCESS THAT GETS BOUGHT OFF AS THE REPAIR PROGRESSES. BECAUSE A DAY LATER I HAPPEN TO BE THE INSPECTOR TO CLOSE OUT THE NON-ROUTINE CARD. I DON'T FEEL THAT MY RESPONSIBILITIES ARE TO REVIEW THE COMPLETE REPAIR BECAUSE IT WAS ALREADY FINISHED AND BOUGHT OFF DURING THE MULTI-STEP SIGNOFFS. I'M NOT SURE HOW THIS EVENT WAS FOUND. I THINK WHOEVER ISSUED THE IMPROPER ENGINEERING AUTH IS THE #1 CONTRIBUTING FACTOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE ISSUES AROSE WHEN HE WAS INFORMED HE HAD SIGNED AND CLOSED A NON-ROUTINE MAINT CARD FOR ACCOMPLISHMENT OF A FUSELAGE SKIN REPAIR ON A B737-300; WITHOUT ANY REFERENCE TO A MAINT PROCEDURE. THIS SKIN REPAIR INCLUDED A SEVENTEEN PAGE ENGINEERING ORDER (EO); THAT ALLOWED FOR DEVIATIONS AROUND VARIOUS ACFT SIDEWALL COMPONENTS AND INTERNAL STRUCTURES IN THE REPAIR AREA OF STRINGER 14-RIGHT. BUT; THE EO DID NOT SPECIFICALLY REFER TO ANY AMM PROCEDURE OR STRUCTURAL REPAIR MANUAL (SRM); AS THE BASIC REPAIR PROCEDURE TO FOLLOW; WHEN USING THE EO FOR DEVIATIONS AS NEEDED. REPORTER STATED EVEN THOUGH HE WAS NOT DIRECTLY INVOLVED WITH THE PROGRESSIVE SIGN-OFFS OF THE REPAIR ITSELF; HE WAS BEING HELD RESPONSIBLE FOR THE REPAIR BEING ACCOMPLISHED WITHOUT ANY SPECIFIC REPAIR PROCEDURE NOTED ON THE ENGINEERING ORDER; BECAUSE HE WAS THE LAST ONE TO CLOSE-OUT AND SIGN THE NON-ROUTINE CARD.