Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Air Traffic Control Issued New Clearance; Flight Crew Returned To Departure Airport
Aircraft
After I leveled off at 9;000 FT; the engines started running rough. There was knocking and rocking of the airplane. The right CHT [indication] was significantly lower than the [left] one. I cycled the mags; when I got to the right engine left mag off; the right engine nearly quit. I returned back to [the departure airport] without any problems. I did not declare an emergency and [ATC] gave me radar vectors around to final [approach].
The pilot of a Cessna 402 experienced a rough running engine in cruise flight. After cycling the magneto switch; he observed that the right engine had a malfunctioning right magneto; so he elected to return to the departure airport where a successful landing was performed.