Flight History
The flight crew executed a missed approach at the Grand Canyon Airport and subsequently diverted to the Bullhead City Airport. During the diversion, minimal icing conditions were encountered, with approximately 1/8 inch of ice accumulating on the aircraft wings.
Icing Encounter
The pilots reported that they cycled the deice boots to shed the ice. They observed no ice on the propeller spinners and did not activate the engines' 'override' ignition systems. According to the airplane's flight manual, use of 'override' ignition was required for flight into visible moisture at or below +5 degrees Celsius (+41 degrees Fahrenheit) to prevent ice ingestion and flameouts.
Engine Flame-Out
While on about a 3-mile final approach for landing with the landing gear and flaps extended, both engines flamed out. The aircraft was subsequently destroyed during an off-airport landing.
Probable Cause
The official probable cause is the failure of the pilot(s) to use 'override' ignition as prescribed by checklist procedures during an encounter with icing conditions, which subsequently led to ice ingestion and dual engine flame-outs. Factors related to the accident were the adverse weather (icing) conditions, the accumulation of airframe/engine ice, and lack of suitable terrain in the emergency landing area.