As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON SHUTDOWN PILOT HEARD FAN MAKING A DIFFERENT SOUND. ON INSPECTION OF FAN, IT WAS FOUND TO BE LOOSE. INDICATING WORN ARMATURE BEARING JOURNALS. AT THIS TIME A NEW DC MOTOR WAS INSTALLED. ON TEAR DOWN OF MOTOR IT WAS FOUND THAT IT NEEDED 2 NEW BEARING 4 NEW BUSHING 1 ARMATURE - WORN JOURNALS