CEN20LA352

The pilot’s failure to maintain airplane control following a reduction of thrust in the left engine during takeoff. The reason for the reduction in thrust could not be determined based on the available evidence.

The pilot departed on a positioning flight in the twin-engine airplane. Videos recorded by multiple airport-based cameras showed the airplane take off from runway 19. Shortly after liftoff, the airplane started turning left, and the airplane developed a large left bank angle as it was turning. The airplane departed the runway to the left and impacted the ground. During the impact sequence, an explosion occurred, and there was a postimpact fire. An airplane performance study showed that during the takeoff, a nose-left sideslip, a left side force, and a left roll occurred, consistent with the loss or reduction in thrust of the left engine. The sideslip was reduced, likely due to inputting rudder to balance the side force, and the airplane briefly rolled right possibly due to an overcorrection in rudder. The airplane pitched up and was able to begin climbing again; however, it continued to lose speed. The sideslip then reversed, and the airplane rolled left again before impacting the ground. The study indicated that before rotating and lifting off, the airplane accelerated to a groundspeed of 98 knots (kts) and an airspeed of 105 kts, which was about 19 kts above the published minimum control speed for the airplane. Therefore, the airplane had achieved sufficient airspeed for the pilot to maintain control despite a loss or reduction in left engine thrust provided he made the appropriate control inputs. The sideslip force calculations indicated that there was a partially successful attempt to maneuver the airplane back to level flight when the airplane rolled back right, but it was not maintained. The right rudder input would need to be held until the thrust asymmetry was corrected. Teardown examinations of the engines and propellers found no evidence of preimpact failure. Both engines exhibited evidence of operation at impact. Damage to the propeller blades and hubs indicated that neither propeller was feathered at impact. The predominant left propeller blade bending and twisting was aft and toward low pitch. The predominant right propeller blade bending and twisting was forward in the thrust direction and toward high pitch. Analysis of the propeller internal witness marks and the blade damage found that the right engine was producing more power than the left engine at initial impact. Based on the available evidence, it could not be determined why the left propeller was not feathered at impact, even though the autofeather system was armed. The rudder trim knob was found 4 units to the left; the aileron trim knob was found 6 units to the right; and the rudder boost switch was found in the OFF position. The before engine starting checklist in the pilot’s operating handbook for the airplane specified that the rudder and aileron trim be set and that the rudder boost switch be on. Therefore, the postaccident positions of the rudder trim knob, aileron trim knob, and rudder boost switch likely indicate the pilot did not follow the before engine starting checklist. With the rudder boost switch not being on, it could not be determined based on the available evidence, what role that system may have had with the pilot attempting to maintain control of the airplane during the asymmetric thrust sequence. Although the pilot’s previous history of significant coronary artery disease and the scar in his left ventricle placed him at increased risk of an acute cardiac event, whether such an event occurred at the time of the accident could not be determined from the available information. Absent evidence of an engine malfunction, the investigation considered whether the left engine’s thrust reduction was the result of a malfunction in the throttle control system or an uncommanded throttle movement due to an insufficient friction setting of the airplane’s power lever friction locks. However, heavy fire and impact damage to the throttle control system components, including the power quadrant and cockpit control lever friction components, precluded determining the position of the throttle levers at the time of the loss of thrust or the friction setting during the accident flight. Thus, the reason for the reduction in left engine thrust could not be determined.

The pilot established the King Air Academy in Phoenix, Arizona. The King Air Academy is a flight training facility that provides initial, recurrent, type rating, and simulator training for the King Air series of airplanes. According to Federal Aviation Administration (FAA) records, the pilot did not hold a type rating for the accident airplane, nor was he required to hold one. According to the autopsy performed by the Winnebago County Coroner’s Office, the pilot’s cause of death was thermal injuries. In addition, left ventricular wall thickening, coronary artery disease with stent present in the circumflex artery, and a 3-centimeter scar in the left ventricular wall from a previous heart attack were identified. No other significant disease was identified. Toxicology testing performed at the request of the coroner by NMS Labs identified caffeine (a mild stimulant found in coffee, tea, and sodas), cotinine (a product of tobacco use), and a carboxyhemoglobin level of 6% (which may be related to smoking). Toxicology testing performed by the FAA Forensic Sciences Laboratory identified carvedilol (a beta blocker used to prevent recurrent heart attacks) and atorvastatin (a cholesterol lowering drug) in the pilot’s blood and urine. These two medications are not considered impairing. Maintenance Records A review of the airplane’s maintenance records revealed no evidence of uncorrected mechanical discrepancies with the airframe, engines, or propellers. The recent maintenance work performed at Chronos Aviation, LLC, consisted of the installation of three new switches for the flaps, the installation of two auxiliary outboard fuel level senders, the adjustment of an ice vane door switch, work on a radar control data bus, and a patch repair to the left propeller de-ice boot. Airplane Servicing A fuel receipt showed that 304 gallons of Jet A fuel was purchased for the airplane at RFD on the day of the accident. Airplane Systems The airplane was certified for single-pilot operation. It was equipped with an autofeather system that was intended for use during takeoff and landing if there was a loss of engine power. The airplane was equipped with a rudder boost system, which was designed to reduce the required rudder pedal force in the event of an engine failure. The published minimum control airspeed (VMCA) was 86 kts. The engine and propeller control levers on the accident airplane were located between the two cockpit seats. The power quadrant included two power levers (which controlled engine power from idle through takeoff) and two propeller levers (which controlled propeller speed and feathering) to the right of the power levers. When the power levers were lifted over the idle gate during ground operation, they controlled engine power and propeller blade angle through the ground fine and reverse ranges. Two engine condition levers were to the right of the propeller levers and had three positions: fuel cutoff, low idle, and high idle. The left condition lever controlled the left engine, and the right condition lever controlled the right engine. Friction lock control knobs were located on the power quadrant. Each power lever had its own friction lock control knob at the base of the quadrant to adjust the power lever’s tension. One friction knob controlled the tension of both propeller levers. Turning the knobs counterclockwise increased tension and turning them clockwise reduced tension. The before engine starting checklist called for these friction locks to be set. Weight and Balance A review of the airplane’s weight and balance data showed that the airplane was within limitations for the accident flight. All the major structural components of the airplane were located at the accident site. Flight control continuity was established for the airframe. The airplane’s fuel system was destroyed by the postimpact fire. All landing gear were found in the retracted position. The postimpact fire consumed most of the instrument and switch panels in the cockpit. The flap handle was found in the full up position; the rudder trim knob was found 4 units to the left; and the aileron trim knob was found 6 units to the right. The autofeather switch was found in the ARM position. The rudder boost switch (a gated switch) was found in the OFF position. The before engine starting checklist called for the rudder and aileron trim controls to be set and for the rudder boost switch to be in the ON position. The power quadrant was destroyed by the impact sequence and the postimpact fire. When compared to an exemplar power quadrant, the throttle levers appeared to be full forward, and the propeller levers appeared to be forward of the feather range. Damage sustained to the control lever friction components precluded determining the friction setting during the accident flight. Teardown examination of the left engine found rotational scoring damage to compressor turbine and power turbine rotor disk faces and adjacent stator structures consistent with loss of operating clearances during engine operation due to impact loads experienced during an accident sequence. The engine propeller shaft was fractured consistent with sudden arrest of rotation during operation (torsional failure). No evidence of preimpact failure was found. The left propeller blades displayed leading edge and chordwise rotational scoring; the blades were predominately bent aft and twisted toward low pitch. Disassembly found marks indicating that the left propeller was not feathered at the time of impact. All the damage was consistent with impact. Teardown examination of the right engine found 360° rotational scoring of compressor turbine and power turbine rotor disk faces and adjacent stator structures consistent with engine operation during impact. The engine propeller shaft was fractured, and the fracture was consistent with torsional failure. No evidence of preimpact failure was found. The right propeller blades displayed leading edge and chordwise rotational scoring; the blades were predominately bent forward in the thrust direction and were twisted toward high pitch. Disassembly found marks indicating that the right propeller was not feathered at the time of impact. All the damage was consistent with impact. On August 20, 2020, about 1542 central daylight time, a Beech B200 airplane (marketed as a King Air 200), N198DM, was destroyed when it was involved in an accident near Rockford, Illinois. The private pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 positioning flight. The purpose of the flight was to relocate the airplane to the pilot's home base at the DuPage Airport (DPA), West Chicago, Illinois. The airplane had been at Chronos Aviation, LLC (a 14 CFR Part 145 repair station), at the Rockford International Airport (RFD), Rockford, Illinois, for maintenance work. Multiple airport-based cameras recorded the accident sequence. The videos showed the airplane taking off from runway 19. Shortly after liftoff, the airplane started turning left, and the airplane developed a large left bank angle as it was turning. The airplane departed the runway to the left and impacted the ground. During the impact sequence, an explosion occurred, and there was a postimpact fire. A video study estimated the airplane’s maximum groundspeed during the takeoff as 105.5 knots (kts). Data recovered from an Appareo Stratus device onboard the airplane showed that about 1538, the airplane began taxing to runway 19. At 1540:34, the airplane crossed the hold short line for runway 19. At 1541:19, the airplane began a takeoff roll on runway 19. At 1541:42, the airplane began to depart the runway centerline to the left of the runway. Subsequent tracklog points showed the airplane gaining some altitude, and the tracklog terminated adjacent to a taxiway in a grassy area. The Appareo Stratus data showed the airplane began to increase groundspeed on a tru