What happened
On June 30, 2019, a Textron Aviation B-300 (marketed as King Air 350), registration N534FF, crashed into a hangar at Addison Airport (ADS) in Addison, Texas. The flight was a Part 91 personal operation en route to St. Petersburg, Florida, carrying a crew of two and eight passengers.
Shortly after departing runway 15, the aircraft experienced a reduction in thrust from the left engine. Approximately seven seconds after liftoff, the propeller speeds of the two engines began to diverge. The aircraft experienced a significant left-wing-down roll and a high sideslip angle. The airplane reached a maximum altitude of approximately 100 feet before impacting the top of a hangar in an inverted attitude. The impact was followed by an explosion and a postimpact fire that consumed the aircraft. All 10 occupants sustained fatal injuries.
The investigation
Investigators analyzed the cockpit voice recorder (CVR), which captured the sequence of events, including the sound of the engines starting, the loss of thrust, and the subsequent stall warnings. A sound spectrum study of the CVR indicated that the left engine's propeller speed decreased significantly while the right engine remained near takeoff power.
Examination of the wreckage revealed that the left engine and propeller were found on the hangar floor, while the main wreckage was located outside the hangar. The investigation found that the left propeller was unfeathered and the landing gear remained in the extended position. While the investigation considered whether an insufficient friction setting on the power lever friction locks led to uncommanded throttle movement, heavy fire and impact damage to the power quadrant and friction components precluded a definitive determination of the lever positions or the friction setting.
Findings
- The pilot failed to maintain control of the aircraft following the reduction of thrust in the left engine.
- The pilot's initial rudder input was likely to the left, which was the opposite of the right rudder input required to counteract the yawing moment from the left engine thrust reduction.
- The pilot did not follow the manufacturer's engine-out procedures, specifically failing to feather the left propeller and failing to retract the landing gear after establishing a positive rate of climb.
- The pilot's rotation occurred before the aircraft reached the recommended rotation speed (Vr), reducing the margin for error and the time available to react to the engine issue.
- The crew did not utilize checklists or discuss emergency procedures, which may have resulted in the failure to properly configure the aircraft or prepare for an engine failure.
- The aircraft was estimated to be at a ramp weight of 15,660 lbs, which exceeded the maximum takeoff weight of 15,000 lbs.