The two pilots, one of whom was a flight instructor, were conducting a cross-country flight in instrument meteorological conditions in the Beechcraft Baron 58.
The pilot reported that, during the climb to 8,000 feet mean seal level (msl), light ice accumulated on the wings’ leading edges. Activation of the deicing boots eliminated about 30% to 40% of the ice. The airplane then climbed to and leveled off at 10,000 feet msl, at which point, the engine speed “fluttered” and the airplane then rolled “quickly to the left” and entered a descending spin.
The flight instructor applied control inputs, and the spin was arrested about 2,500 feet msl. The pilot landed the airplane without further incident in Dixon, Ill.
Post-accident examination and testing of the airplane revealed substantial damage to the right wing and elevator control surface, which was consistent with forces sustained from excessive accelerations. Radar data showed that the airplane descended 7,500 feet in about 30 seconds.
A weather briefing for the flight showed that an airmen’s meteorological information for moderate icing conditions was in effect and that light showers, rain, and snow were forecast throughout the area about the time of the accident.
The deicing boots were unable to shed the accumulated ice, which adversely affected the airplane’s performance and resulted in the temporary loss of airplane control.
The pilot reported that he did not fly in such weather conditions unless accompanied by an experienced pilot.
The NTSB determined the probable cause as the pilots’ improper decision to continue flight in icing conditions after the deicing boots could not shed accumulated ice, which resulted in a temporary loss of airplane control.
NTSB Identification: CEN15LA021
This October 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.