What was found
SHORTLY AFTER DEPARTURE, ACFT BEGAN A VIOLENT SHAKING AND FLUTTER. PILOT REDUCED SPEED AND RETURNED TO AIRPORT. PILOT STATED THE ACFT WAS ALMOST UNABLE TO BE CONTROLLED. AN UNEVENTFUL LANDING WAS MADE. INSP REVEALED THE LT ELEV TRIM TAB ACTUATING ROD HAD BROKEN APPROX 1 INCH FROM THE END WHERE IT ATTACHED AT THE JACK SCREW. THIS APPARENTLY ALLOWED TRIM TAB TO FLUTTER AND THIS ACTION WAS FED BACK TO THE CONTROL YOKE. BREAK OCCURRED AT A POINT THAT REMAINS WELL WITHIN THE CONFINES OF THE HORIZ STAB. SUBMITTER SUGGESTS INSPECTION OF THIS AREA ON INSPECTING THE AD CONCERNING THE RIVET REPLACEMENT HAD BEEN C/W.