A B727-200 WAS DISPATCHED AND FLOWN WITH INCORRECT ENG MOUNT CONE BOLTS AND VIBRATION ISOLATORS INSTALLED.

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IT HAS BEEN BROUGHT TO MY ATTN THAT AN ENG INSTALLATION THAT I WAS INVOLVED IN WAS DONE IMPROPERLY. APPROX 7 MONTHS AGO (APR/XX/97); WE WERE AT XYZ; A 3RD PARTY REPAIR STATION; HAD ACFT YYY HERE FOR MAINT. 3 ENGS WERE REMOVED AND INSTALLED HERE. I BELIEVE THIS PARTICULAR ACFT ALSO UNDERWENT A 'C' CHK HERE AS WELL DURING THIS SAME TIME FRAME. HOWEVER; I CANNOT BE CERTAIN DUE TO THE NUMBER OF ACFT WE (XYZ) PERFORM MAINT ON AND THE TIME SPAN BTWN THEN AND NOW. UPON COMPLETION OF THE MAINT PERFORMED; THE ACFT WAS RETURNED TO SVC AND LEFT OUR FACILITY. ON OCT/XX/97; I WAS INFORMED THAT THE ACR FOUND THAT ALL THE ENG MOUNT BOLTS (CONE BOLTS) WE INSTALLED ON THE ENG WERE NOT COMPATIBLE WITH THE TYPE OF ACFT ENG MOUNTS (ISOLATORS) INSTALLED ON THE ACFT. I WAS TOLD BY OUR INSPECTION DEPT MGMNT THAT ACR MAINT PERSONNEL HAD SINCE FIXED THE PROB BUT THEY (ACR) WANTED TO KNOW HOW WE (XYZ) COULD LET AN ACFT OUT OF MAINT LIKE THAT. IN THE DAYS THAT FOLLOWED; I WAS TOLD THAT ONLY THE FORWARD CONE BOLTS ON THE ENGS WERE WRONG. ACR MAINT HAD REMOVED ALL 3 ENGS; REPLACED ONLY THE FORWARD CONE BOLTS AND REINSTALLED THE ENGS TO THE AIRPLANE. SHORTLY AFTER THAT; I LEARNED THAT THE AFT CONE BOLTS WERE WRONG TOO AND THAT ACFT (YYY) WOULD BE BROUGHT BACK HERE TO XYZ TO REMOVE ALL 3 ENGS; INSTALL THE PROPER PART NUMBER AFT CONE BOLTS; AND REINSTALL THE ENGS. WHICH; AT THE DATE OF THIS LETTER WE HAVE DONE. I WAS INFORMED THAT XYZ WOULD SEND A VOLUNTARY LETTER OF DISCLOSURE TO THE FAA CONCERNING THE INCIDENT. I WAS ASKED BY OUR INSPECTION DEPT WHY I WOULD SIGN MY NAME TO A BLOCK WHICH TELLS YOU TO ONLY USE A CERTAIN CONE BOLT IN THIS PARTICULAR INSTALLATION IF I KNEW IT WAS THE WRONG CONE BOLT AND COULD I SHED ANY LIGHT ON THE SUBJECT? THE ANSWER THAT I GAVE IS THE ONE I BELIEVE IN MY HEART TO BE RIGHT AND THAT IS; I WOULDN'T PUT THE PART ON IF I KNEW IT WAS WRONG. I MARKED IN THE BOX THAT TRAINING WAS A FACTOR BECAUSE UNTIL A FEW WKS AGO I DIDN'T KNOW HOW TO TELL THE DIFFERENCE BTWN THE 2 TYPES OF ISOLATORS. IN THE MAINT MANUAL IT SHOWS 2 TYPES OF ISOLATORS; THEY ARE THE ELASTOMER ISOLATOR AND THE METALFLEX ISOLATOR. HOWEVER; THE MAINT MANUAL DOES NOT SAY WHICH TYPE ISOLATOR IS WHICH. IN THE DESCRIPTION AND OP PART OF THE MANUAL CONCERNING ENG MOUNTS IT SHOWS THE 2 DIFFERENT TYPES OF ISOLATORS AND SHOWS ONE TYPE AS EFFECTIVE FOR EARLY MODEL B727 ACFT AND THE OTHER TYPE AS EFFECTIVE FOR LATE MODEL B727 ACFT. SINCE I DON'T KNOW OF ANY OBVIOUS WAY TO TELL THE DIFFERENCE BTWN AN EARLY OR LATE MODEL B727 I INSTALLED THE PARTS I BELIEVED TO BE CORRECT. THEREFORE; I BELIEVE THE MISTAKE I HAVE MADE WAS AN HONEST ONE. BASICALLY; IT SAYS THAT BEFORE ANY ENG WILL BE INSTALLED; THE PART NUMBER OF THE ISOLATOR; AND THE PART NUMBER OF THE CONE BOLT WILL BE VERIFIED AND XREFED FOR THE EFFECTIVITY TO THE ACFT AND DOCUMENTED TO THE WORK CARD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATES THE PROC JOB CARD WAS WRITTEN IN A GENERAL WAY TO COVER SEVERAL MODEL B727 ACFT AND DID NOT SPECIFY PART DIFFERENCE. THE RPTR STATES THE FAA HAS NOT MADE ANY CONTACT.