The Cessna 208B Grand Caravan EX conducting flight testing for Raisbeck Engineering that crashed on November 18 near Snohomish, Washington, broke apart in-flight, according to the NTSB’s preliminary report. All four crewmembers on board died in the crash of the turboprop single, which was registered as N2069B.
Raisbeck was conducting flight testing to expand its aerodynamic drag reduction system STC for the Cessna 208B to include the 208B EX. The accident flight was performing baseline testing of the airplane’s aft center of gravity stall characteristics.
“Witnesses reported that they observed the airplane break up in flight and watched pieces floating down,” the report said. “The airplane then descended in a nose-low near-vertical corkscrew maneuver toward the ground. Several witnesses reported seeing a white plume of smoke when they observed the airplane break into pieces.”
During the last 12 seconds, the radar track indicated that the airplane’s descent rate exceeded 14,000 fpm and gradually lessened to 8,700 fpm. After reviewing the radar track, the right-seat pilot who flew the airplane the day prior to the accident believed that they were on the second-to-last maneuver of the test card, which specified 96 knots indicated airspeed; flaps in landing configuration; 930 foot-pounds of torque; propeller RPM fully forward; and accelerated 30-degree bank to the left.