Incident
During a flight at 6,000 feet MSL, the aircrew encountered icing conditions and activated the de-ice and anti-ice equipment. After descending and exiting the icing conditions, the de-ice and anti-ice equipment was deactivated. The captain inspected the propeller spinners and observed a small buildup of ice, which was considered minimal. Subsequently, the continuous ignition was turned off. Shortly thereafter, while on final approach at approximately 1,000 feet AGL and 1 to 1.5 miles from the airport, the right engine lost power without warning. The copilot feathered the right propeller, and the approach was continued. However, at about 200 feet AGL, the other engine also lost power. The aircraft was landed without further incident.
Investigation
During the investigation, ice was found on the ground under the wings. No mechanical problems or fuel contamination were discovered. The aircraft had a history of flameouts due to ice buildup and release from the spinners. The ignition switch was labeled with positions 'NORM', 'CONT', and 'OVRD'. To obtain continuous ignition in flight, the switch must be in the 'OVRD' position. There was no specific warning in the flight manual to use continuous ignition (OVRD) in icing conditions.