What was found
PILOT REPORTED, ENROUTE HEARD A LOUD "THUD" COMING FROM THE FLOOR IN THE VICINITY OF THE PILOTS STATION. THERE WERE NO FLUCTUATIONS ON ANY GAUGES, NO ABNORMAL FEELING IN CONTROLS, AND NO LIMITATIONS WERE EXCEEDED. ONLY 3 MINUTES FROM BASE AIRPORT, ABORTED FLIGHT DUE TO A MECHANICAL PROBLEM, AND MADE AN UNEVENTFUL LANDING. THIS IS THE 8TH DOCUMENTED INCIDENT OF AN UNKNOWN "THUD" IN THE ACFT SINCE OCTOBER 2011, BY 3 DIFFERENT PILOTS.