What was found
FLIGHT 3962 TO SYRACUSE REPORTED A RYTHMIC THUMPING SOUND EVERY 3-5 SECONDS IN FLIGHT AT VARIOUS PROP RPM SETTINGS. NO THUMPING REPORTED WHEN GEAR AND FLAPS EXTENDED. AIRCRAFT WAS INSPECTED AND FROM SYRACUSE A FERRY PERMIT WAS ISSUED FOR AIRCRAFT TO LOCATE TO MIDDLETOWN MAINTENANCE. MAINTENANCE TROUBLESHOT SYSTEM AND FOUND THE GEAR CYCLING WHILE IN THE UP POSITION. RELAYS 3261-K13 AND 3261-K11 WERE REPLACED AND THE SYSTEM OPERATIONAL CHECKED. ALL CHECKS GOOD AND AIRCRAFT RETURNED TO SERVICE.