WHILE WORKING AN AIRWORTHINESS DIRECTIVE TO CHANGE THE GAMBLE PLATES ON THE OUTBOARD FLAP #8 AFT FLAP SUPPORT ON A B777-200 ACFT; MECHANIC REALIZES HE INSTALLED THE REQUIRED TWELVE POINT BOLTS IN THE WRONG DIRECTION.

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WHILE I WAS WORKING ON AN AIRWORTHY DIRECTIVE FOR CHANGING THE GIMBAL PLATES ON ACFT X; I REALIZED I HAD PUT THE 12-POINT HEAD BOLTS IN THE WRONG LOCATION ON ACFT Y. I MISTAKENLY INSTALLED THEM ON THE #8 AFT FLAP SUPPORT GAMBLE PLATES ON ACFT Y. CONTRIBUTING FACTORS: WHILE WORKING ON AN AIRWORTHY DIRECTIVE; ON THE GAMBLE PLATE MODE ON ACFT X; I REALIZED I HAD INSTALLED THE 2 12-POINT HEAD BOLTS IN THE WRONG LOCATION ON ACFT Y. I MISTAKENLY INSTALLED THEM ON THE #8 FLAP SUPPORT MECHANISM ON ACFT Y. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE MOST OUTBOARD LEFT AND RIGHT FLAP JACK SCREW GAMBLE PLATES WERE BEING REPLACED WITH A BEEFIER PLATE PER AN AIRWORTHINESS DIRECTIVE (AD). PART OF THE AD; REQUIRED REMOVING THE OLD SIX-POINT HEAD BOLTS AT THIS LOCATION AND INSTALLING TWO NEW TWELVE-POINT TYPE HEAD BOLTS; TO ALLOW FOR BOLT CLEARANCE WHEN FLAPS ARE RETRACTED; DUE TO THE THICKER GAMBLE PLATES. A FELLOW MECHANIC HAD NOTICED THAT REPORTER HAD INSTALLED THE TWO BOLTS IN THE WRONG DIRECTION ON THE ACFT HE WAS WORKING AT THE TIME. REPORTER STATED HE THEN REALIZED HE HAD INCORRECTLY INSTALLED THE SAME TYPE BOLTS; AT THE SAME LOCATION; ON THE PREVIOUS ACFT HE WORKED.