What was found
(CAN) DURING MORNING WARM-UP AND PRE FLIGHT CHECKS, PILOT FELTS STRONG VIBRATIONS. WHILE REDUCING TROTTLE CONTROL, ENGINE EXPERIENCED POWER LOSS. MAINTENANCE INSPECTION WAS PERFORMED. THE RESULT WAS THE FOLLOWING: THE ENGINE HAS SUFFERED A NR 4 EXHAUST VALVE SEIZURE. AS A RESULT THE VALVE PUSH ROD AND PUSH ROD TUBE HAS BEEN BENT. FURTHER INVESTIGATION SCHEDULED. WILL BE CARRIED OUT ON MAY 6TH AND 7TH TO DETERMINE IF THERE ARE ANY FURTHER DAMAGES TO THE CYLINDER HEAD OR VALVE TRAIN.