Accident Summary
On an unspecified date, aircraft N500AK encountered icing in flight before the start of an instrument landing system (ILS) approach. Radar data indicated that before reaching the outer marker, the aircraft slowed in a manner consistent with a power reduction or partial loss of power. It subsequently entered a steep descent and crashed.
Flight History
During the approach, the aircraft experienced icing conditions. The exact time of day, weather conditions beyond the presence of icing, and any air traffic control communications were not specified in the source.
Examination Findings
Post-crash examination revealed that the engines were not operating at impact and that the propellers had been feathered. No preimpact part failure or malfunction of the engines, propellers, or anti-ice system was found. Evidence indicated that the engine inlet anti-ice annunciator lights and the stability augmentation system (SAS) fault warning light were illuminated during impact.
Engine Manufacturer Report
The engine manufacturer reported that flameouts had occurred in other aircraft during or following operation in icing conditions, sometimes after descent into warmer air.
Flight Manual Guidance
The flight manual noted that if icing was encountered with the anti-ice system off, the recommended procedure was to select continuous ignition, then select engine and propeller heat, applying heat to one engine at a time and ensuring the first engine was operating satisfactorily before selecting the second engine, and to engage SAS heat.