CEN16FA146

The private pilot, who was the owner of the airplane, and a flight instructor were performing a recurrent training flight. Radar data showed that the airplane departed and climbed to an altitude about 5,000 ft above ground level. About 5 minutes after takeoff, the airplane conducted a left 360° turn followed by a right 360° turn, then continued in level flight for about 2 minutes as it slowed to a groundspeed of about 90 knots, which may have been indicative of airwork leading to slow flight or stall maneuvers. The airplane then entered a steep bank and impacted the ground in a nose-low attitude. Both engines and propellers displayed evidence of operation at the time of impact, and postaccident examination revealed no mechanical anomalies that would have precluded normal operation of the airframe or engines. The instructor had a history of obstructive sleep apnea. The investigation was unable to determine how well the condition was controlled, if he had symptoms from the condition, or if it contributed to the accident. Toxicology testing revealed low levels of ethanol in specimens from both pilots; however, it is likely that some or all of the ethanol detected was a result of postmortem production, and it is unlikely that alcohol impairment contributed to the accident. Toxicology testing also detected the primary psychoactive compound of marijuana, tetrahydrocannabinol (THC), and its metabolite, tetrahydrocannabinol carboxylic acid (THC-COOH), in specimens obtained from comingled remains; the investigation was unable to reliably determine which pilot had used the impairing illicit drug. Additionally, it is not possible to determine impairment from tissue specimens; therefore, the investigation was unable to determine whether THC impaired either of the pilots or if it may have contributed to the accident.

According to the Model 690B Pilot's Operating Handbook, Section II, Limitations, the airplane's stall speed with landing gear and flaps retracted at gross weight (Vs) was 78 knots indicated airspeed (KIAS), and its minimum controllable airspeed (Vmca) was 83 KIAS. On April 9, 2016, at 0951 central daylight time, a Rockwell International 690B, N690TH, was destroyed when it impacted terrain while maneuvering near Taylor, Texas. The private pilot and flight instructor were fatally injured. The airplane was privately owned and operated under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight, which departed from Georgetown Municipal Airport (GTU), Georgetown, Texas, at 0941. An acquaintance of the pilot stated that the purpose of the accident flight was for the pilot to conduct annual recurrent training to meet insurance requirements. He stated that, as the pilot and instructor were conducting a walkaround of the airplane before the flight, he heard the instructor telling the pilot that they were going to perform "air work" at an altitude of 4,000 - 5,000 ft, followed by instrument approaches. The acquaintance thought that an altitude of 4,000-5,000 ft to perform air work was low and that it should be at least 10,000 ft. Radar data showed that the airplane departed GTU and proceeded east as it climbed to an altitude about 5,500 ft mean sea level (5,000 feet above ground level). About 5 minutes after takeoff, the airplane completed one 360° turn to the left followed by one 360° turn to the right. The airplane then resumed its easterly course in level flight for about 2 minutes, during which it slowed to a ground speed of 90 knots before rapidly descending. A witness near the accident site stated that the airplane entered a turn at low altitude and then went "totally sideways" and "started coming down" as if it was performing "tricks." She said that the left wing of the airplane was pointed to the sky and the right wing was pointed to the ground. She described the engine speed as "slow" and stated that the sound did not change as the airplane maneuvered before impact. She said the airplane descended with the nose pointing straight down toward the ground. According to medical records, the pilot had high blood pressure treated with the non-impairing blood pressure medication valsartan. Central Texas Autopsy PLLC, Lockhart, Texas, performed an autopsy on the pilot. The cause of death was listed as multiple blunt force injuries; however, the autopsy was limited to an external examination due to the extent of the injuries and was unable to identify any significant natural disease. NMS Labs' toxicology analysis, conducted as part of the autopsy, detected caffeine (a mild stimulant found in coffee and tea), acetaminophen (a non-narcotic pain and fever medication often marketed as Tylenol) and ethanol (a central nervous system depressantfound in beer and wine but also produced after death by decomposition) in muscle. The toxicologist commented: "The ethyl alcohol concentration increased from 45 to 78 mg/100 g of muscle over multiple analyses. The nature of the specimen and/or the container type, which may not contain preservative, may explain the variable quantitative results. Small amounts of ethanol may also be produced by decomposition of the tissue." According to medical records, the flight instructor had high blood pressure treated with the non-impairing blood pressure medication metoprolol and obstructive sleep apnea treated with a CPAP device. Central Texas Autopsy PLLC conducted an autopsy on the instructor and listed the cause of death as multiple blunt force injuries; however, the autopsy was limited to an external examination due to the extent of the injuries and was unable to identify any significant natural disease. NMS Labs' toxicology analysis, conducted as part of the autopsy, detected acetaminophen (a non-narcotic pain and fever medication often marketed as Tylenol), beta-phenethylamine (a product of tissue decomposition) and a non-quantified amount of ethanol in muscle tissue.The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on specimens from comingled remains, and the investigation was unable to reliably determine which specimen came from which individual. Testing of specimens attributed to the pilot documented that valsartan was not detected in muscle or lung and ethanol was not detected in muscle or liver. However, testing of specimens attributed to the pilot detected the primary psychoactive compound of marijuana, tetrahydrocannabinol (THC), at 35.2 ng/g in liver, at 52.9 ng/g in lung, and identified a non-quantified amount in muscle. THC's inactive metabolite, tetrahydrocannabinol carboxylic acid (THC-COOH), was detected at 50.4 ng/g in liver, 18.8 ng/g in lung, and a non-quantified amount was detected in muscle. Additionally, testing of specimens attributed to the instructor pilot documented ethanol at 20 mg/dl in liver and heart; dextromethorphan (a cough suppressant) in liver, kidney and muscle; and valsartan (a blood pressure medication) in liver but not muscle. The report stated that THC and THC-COOH were not detected in muscle attributed to the instructor. Dextromethorphan is generally not considered impairing at therapeutic levels. The airplane was registered to the pilot on April 23, 2015. The pilot received dual flight instruction in the accident airplane from April 13 to May 25, 2015. The total flight instruction during this period was 34.2 hours. A logbook endorsement, dated May 15, 2015, showed that he competed a flight review, a pilot-in-command landing proficiency, and an instrument competency check. The 54-year-old pilot held a Federal Aviation Administration (FAA) third-class medical certificate. The 66-year-old instructor held an FAA second-class medical certificate. The airplanecame to rest upright in a field oriented on a magnetic heading about 130° and was consumed by postcrash fire. The empennage was folded forward, and the left and right wing leading edges were crushed aft. The flap control mechanism was in a position consistent with flaps up. The elevator trim tab was about 16.4° down (nose-up). The flight control system exhibited separations consistent with overload throughout. The airplane's nose, forward fuselage, both engines, and propellers were embedded about 3 ft into the ground. Both propellers exhibited S-shaped bending, twisting, and chordwise scratching. The left and right propeller pistons had circumferential signatures consistent with blades angles about 18.6° and 15.5°, respectively. The left engine throttle control was in the forward position, and the right engine throttle control was in about the mid-position. The left engine condition lever was broken off, and the right engine condition lever was in the forward position. Examination of both left and right engines revealed extensive impact damage; neither engine could be rotated by hand. Both engines displayed bending of the first stage impeller blades in the direction opposite of impeller rotation, and debris in the first stage of the compressor consistent with impact with the ground. Both engines had metal deposits on the turbine rotors and stators, consistent with engine operation at the time of impact. Examination revealed no mechanical anomalies that would have precluded normal operation.