As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB-OUT, 'AFTER T/O' CHECKLIST, WHEN AUTO-FEATHER DESELECTED ARM LIGHT REMAINED ILLUMINATED. COMPLETED A NORMAL APPOACH AND LANDING, TAXIED TO TERMINAL. MAINTENANCE T/S SYSTEM BY SWAPPING THE NR 1 AND NR 2 TSCU'S, DID NOT SOLVE PROBLEM REPLACED THE ARM CONTROL RELAY (6121-KS). SYSTEM WAS OPERATIONALLY CHECKED SATISFACTORILY, AIRCRAFT RETURNED TO SERVICE. (M)