As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PRIOR TO DEPARTURE A "MAG-DROP" TEST WAS CARRIED OUT AND BOTH MAGNETOS WERE FUNCTIONING NORMALLY. AFTER TAKEOFF AND DURING A HOVER TAXI PRIOR TO DEPARTURE THE PILOT NOTICE THE ENGINE WAS RUNNING ROUGH AND MORE THAN NORMAL ENGINE POWER WAS REQUIRED FOR HOVERING FLIGHT. THE PILOT RETURNED THE HELICOPTER TO THE HELIPAD AREA, CARRIED OUT ANOTHER "MAG-DROP" TEST AND FOUND THAT THE LT MAGNETO WAS INOPERATIVE. LEFT MAGNETO REPLACED, ENGINE FUNCTIONS NORMALLY.