What was found
BEARING FAILED AFTER INCORRECT INSTALL. INSP OF WHAT APPEARED TO BE EXCESS BACKLASH ON THE 47-620-497-1 FAN DRIVE GEAR ASSY. UPON REMOVAL OF FAN DRIVE QUILL ASSY, NOTED NEW GEAR PATTERN AFT AND HIGH RUNNING OFF HEEL OF 530 GEAR. UPON REMOVAL OF CLUTCH, DETERMINED 47-620-628-3 DUPLEX BEARING SET FAILED DUE TO IMPROPER INSTALL WHEN NEW CLUTCH ASSY INSTALLED 56.7 HRS PRIOR. PER BELL TECH BULLETIN NR 47-75-4, REV A, PAGE 4 OF 4, FIG 4, DUPLEX BEARING SET IS TO BE INSTALLED WITH THRUST SIDE OF EACH BEARING OTBD AS WRITTEN ON BEARING RACE. HOWEVER, BEARING SET HAD BEEN INSTALLED IN A TANDUM CONFIG AND FAILED WITHIN 56.7 HOURS. TRANS TSO: 165.1 HRS. DUPLEX BEARING: 56.7 HRS SINCE INCORRECT ASSY AND INSTALL.