What was found
ACFT RETURNING TO SERVICE, NOTED A VIBRATION IN THE ACFT. DETERMINED PROBLEM TO BE IN LT GENERATOR. ACFT LANDED TO DROP PASSENGER. CREW ADVISED MX OF PROBLEM, DISPATCHED A MECH THE FOLLOWING MORNING WITH A STARTER/GENERATOR. INSTALLED SAME, NO VIBRATIONS NOTED, ACFT RELOCATED TO BASE. O/H UNINSTALLED, SN 2017XL FAILED UNIT HAD APPROX 5 MONTHS AND 121 HRS IN SERVICE. FAILED UNIT WAS O/H IN TEXAS. FAILED PART WAS INSTALLED ON 2/26/2010.