What was found
AT ALTITUDE HEARD A LOUD POP. RUDDER TRIM NRS STARTED SPINNING SMOKE CAME OUT OF THE RUDDER TRIM BOX. R & R RUDDER TRIM INDICATOR IAW MM 27-22-22-4. OPS CHECK NORMAL IAW MM 27-22-00-5 AND 27-12-00-5 OPS CHECK NORMAL. ALSO CHECK WIRES IAW AWM 27-22-05, 27-22-03, 27-22-04 NO DEFECTS NOTED AT THIS TIME, ACFT OK FOR SERVICE. NOTE: INSTALLED BORROWED PART, 35-930-1001 S/N 529.