What was found
(CAN) THE CREW REPORTED VIBRATIONS SHORTLY AFTER TAKEOFF AND WAS ATTEMPTING TO RETURN TO POINT OF DEPARTURE. THE AC CRASHED. ALL ON BOARD WERE FATALLY INJURED. BOTH ENGINES SHOWED INDICATIONS CHARACTERISTIC OF THE ENGINES PRODUCING LOW POWER OR WINDMILLING UNDER AIR LOADS AT THE TIME OF IMPACT. THERE WERE NO INDICATIONS OF ANY PRE-IMPACT ANOMALIES TO ANY OF THE COMPONENTS OBSERVED. MFG WILL CONTINUE INVESTIGATING THE EVENT AND ADVISE OF ROOT CAUSE ONCE ESTABLISHED. (TC NR 20080423011)