What was found
AFTER TAKEOFF, AROUND 2,500 FEET, FLIGHT CREW WAS UNABLE TO TRIM AIRCRAFT WITH CAPTAIN, F/O SUITECASE OR ALTERNATE TRIM. AIRCRAFT WAS FLOWN WITH ELEVATORS ONLY. AROUND 250 KTS VIBRATION WAS FELT THROUGHTOUT THE AIRCRAFT. AFTER LANDING, TRIM SYSTEM OPERATED NORMALLY.