A MECHANIC DESCRIBES SOME OF THE FACTORS THAT HE BELIEVES CONTRIBUTED TO HIS INSTALLING THE WRONG FLEET TYPE VERTICAL NAVIGATION (V-NAV) SOFTWARE ON A B737-300 AIRCRAFT.

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I ACCOMPLISHED ENGINEERING ORDER; ACTIVATION OF VERT NAV. IT WAS BROUGHT TO MY ATTN THAT PLANNING FOUND I LOADED THE WRONG SOFTWARE ON THE ACFT; WHICH IS STEP 4 OF THE ENGINEERING ORDER. I ACCOMPLISHED A FEW ACO'S IN THE PAST AND NOTICED THAT THE SOFTWARE DOESN'T HAVE AN ALERT NUMBER ON THE TAG BUT IT DOES HAVE A PART NUMBER ON IT. SO WHEN I WAS WORKING IN THE HANGAR; I OPENED UP THE SOFTWARE BOOK AND REMOVED THE CARD. EVIDENTLY; THE CARD I REMOVED WAS THE PERFORMANCE SOFTWARE. WHEN I WAS DONE LOADING; I VERIFIED THE PART NUMBER INSTALLED WAS CORRECT. IT WAS CORRECT ACCORDING TO THE DISK I HAD IN MY HAND; BUT IT WASN'T CORRECT FOR THE FLEET TYPE. I BELIEVE THAT THIS POSSIBLY COULD HAVE BEEN PREVENTED IF THE ALERT NUMBER WAS ON THE DISK OR IF THE PART NUMBER WAS LISTED IN STEP 4 OF THE ENGINEERING ORDER INSTEAD OF THE ALERT NUMBER IN STEP 4A; WHICH IS NOT ON THE DISK. ALSO; THE LAST STEP IN STEP 4; IS TO FILL OUT THE TABLE AND WRITE DOWN THE PART NUMBER INSTALLED. I BELIEVE THAT IF THE CORRECT PART NUMBER IS LISTED ON THE TABLE IT WOULD BE EASIER TO COMPARE TO NEW UPLOADED PART NUMBER IN THE CDU.