WPR18FA116

The pilot's exceedance of the airplane's critical angle of attack while maneuvering in the airport traffic pattern, which resulted in an aerodynamic stall and subsequent spin.

The private pilot and pilot-rated passenger were conducting a daytime visual flight rules cross-country personal flight and neared their intended destination airport. Witnesses observed the airplane on the left downwind leg of the airport traffic pattern with no airplanes ahead of it. As the airplane neared an area where a turn from downwind to base would normally be performed, the pilot initiated a steep left turn; it then entered a spin and descended into the ground. Shortly after impact, a postcrash fire ensued, which destroyed the airplane. An examination of the airframe, engine, and related systems revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Investigators were unable to determine how much fuel was on board the airplane at the time of the accident. Regardless of the fuel quantity, weight and balance calculations at various fuel loads placed the center of gravity within the manufacturer's limits. It is likely that, while maneuvering in the airport traffic pattern, the pilot exceeded the airplane's critical angle of attack, which resulted in an aerodynamic stall at an altitude too low to recover. Although the investigation could not determine who was manipulating the controls at the time of the accident, and given the pilot rated passenger's lack of recent flight experience, it is likely that the owner of the airplane was manipulating the controls at the time of the accident and was ultimately responsible for maintaining flight control of the airplane.

Pilot An autopsy of the pilot was performed by the Ventura County Medical Examiner's Office, Ventura, California. His cause of death was multiple blunt force injuries. Toxicology testing performed at the FAA Forensic Sciences Laboratory was negative for carbon monoxide, cyanide, volatiles, and drugs. Passenger An autopsy of the passenger was performed by the Ventura County Medical Examiner's Office, Ventura, California. His cause of death was multiple blunt force injuries. Toxicology testing performed at the FAA Forensic Sciences Laboratory identified an unspecified level of naproxen in the urine, 0.032 (µg/mL, µg/g) of diphenhydramine in the blood, and an unspecified level of diphenhydramine in the urine. Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. It is available over the counter under the names Benadryl and Unisom. Diphenhydramine carries the following Food and Drug Administration (FDA) warning: may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). Compared to other antihistamines, diphenhydramine causes marked sedation; it is also classed as a CNS depressant and this is the rationale for its use as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. The levels of diphenhydramine thought most likely to cause effects are between 0.0250 and 0.1120 ug/ml. Naproxen is an over the counter analgesic commonly marketed with the name Aleve. It is also available by prescription, most often with the name Naprosyn. It is not generally considered impairing. At 1355, the Camarillo Airport (CMA), Camarillo, California, automated weather observation station, located about 8 miles south of the accident site, reported wind variable at 3 knots, visibility 10 miles, clear sky, temperature 64°F, dew point 11°F, and an altimeter setting of 30.02 inches of mercury. Pilot The pilot held a private pilot certificate with an airplane single-engine land rating. A Federal Aviation Administration (FAA) second-class airman medical certificate was issued to the pilot on May 18, 2016, with a limitation of "must wear corrective lenses." At the time of his most recent medical application, the pilot reported that he had accumulated 362.9 hours of flight experience, of which 35.6 hours were in the previous 6 months. The most recent entry in the pilot's logbook was dated March 16, 2018. At that time, he had accumulated 491.6 hours of flight experience, of which 312.1 hours were in the same make and model as the accident airplane. Passenger The passenger held a private pilot certificate with an airplane single-engine land and instrument airplane rating. An FAA third-class airman medical certificate was issued to the pilot on February 27, 2018, with a limitation of "must wear corrective lenses for near vision." At the time of his most recent medical application, the pilot reported that he had accumulated 368.7 hours of flight experience, with none in the previous 6 months. Examination of the accident site revealed that the airplane impacted trees, a brick wall, and terrain about 0.7 mile east of SZP. The initial point of impact was identified by separated tree limbs about 20 ft above the ground, and an adjacent brick wall about 8 ft high was also struck during the impact sequence. Severed tree limbs, plexiglass, canopy structure, and various debris were located throughout the debris path, which was about 30 ft long and oriented on a heading of about 160° magnetic. The main wreckage came to rest upright on a heading of about 043° magnetic. Examination of the fuselage revealed that the center portion of the fuselage from the instrument panel to the bulkhead aft of the seats was mostly consumed by fire. The fuselage structure from the bulkhead aft of the seats to the forward part of the vertical stabilizer, was buckled and compressed inward with an almost circular impression. The empennage was slightly displaced left. The vertical stabilizer and rudder remained attached via their mounts, with the vertical stabilizer buckled throughout. The bottom 7 inches of the rudder was displaced left and crushed upward. The left horizontal remained partially attached by the rear spar attach point and the outboard 24 inches were buckled and bent slightly upward. The right elevator remained attached via its mounts, with the outboard 29 inches buckled and bent throughout. The trim tab remained attached to its mounts. The trim tab actuator screw was extended about ½ inch from the forward side of the unit. The right horizontal stabilizer remained attached via both its mounts. The right elevator was bent and buckled throughout, and the trailing edge was bent upward. The left wing was mostly separated from the fuselage. The forward spar attach point remained attached to the fuselage and was cut during wreckage recovery. The wing was bent and buckled throughout. The wing at the flap/aileron junction was bowed with both the inboard and outboard portion of the wings bent downward. The flap and aileron remained attached via their mounts. The outboard half of the aileron was crushed inward. The right wing was mostly consumed by fire. The right main spar remained attached to the fuselage, however, most of the wing structure aft of the spar was separated. The aileron remained attached via all its mounts and exhibited fire damage. The flap remained attached to the wing structure. Elevator control continuity was established from the elevators forward to the bell crank located just aft of the cabin seating area; the rod end was separated between the bell crank and torque tube, and elevator control continuity continued from the bell crank forward to the control column. Rudder control continuity was established from the rudder to the rudder pedals; however, the left rudder cable was separated just aft of the rudder pedals and exhibited splayed signatures, consistent with overload. Aileron control continuity was established from the left aileron through the bell crank to the inboard portion of the wing where the torque tube was separated, consistent with impact damage, and continued to the left control stick. The right aileron control cable was continuous through the bell crank to about mid span of the flap where the torque tube was separated, consistent with impact damage; the torque tube continued to the right control stick. The interconnect for the left and right control sticks was impact and fire damaged. Both flap rod end bearings were separated. The flap actuator measured about 2.25 inches in length, consistent with about one-half flaps, or about 20°. Examination of the engine revealed that it remained attached to the forward portion of the airframe via its mounts. All of the engine accessories remained attached to the engine, and all ignition leads were secure to their respective spark plugs. The upper spark plugs exhibited wear and color consistent with normal operation. All four cylinders were examined internally using a lighted borescope with no anomalies noted. The crankshaft was rotated by hand using the propeller. Rotational continuity was established throughout the engine and valve train. Thumb compression was obtained on all 4 cylinders. The oil suction screen was free of debris. The oil filter was consumed by fire. The left and right magnetos exhibited fire damage, which precluded functional testing. The carburetor was thermally discolored and damaged. The throttle and mixture levers were connected via their respective control arms and moved freely from stop to stop. The fuel finger screen was free of debris. The internal floats were consumed by fire. The venturi was partially melted. The fuel inlet line was secure at the carburetor fitting. Examination of the propeller revealed that it remained attached to the engine crankshaft. One propeller blade was slight