CEN17FA111

The failure of the pilots to apply prompt and/or correct flight control inputs to adequately recover from the intentional aerodynamic spin.

The flight instructor and the commercial pilot receiving instruction were conducting a local training flight to practice aerodynamic spins. A review of air traffic control radar track data established that the airplane entered two aerodynamic spins during the flight. The first aerodynamic spin began at 10,300 ft mean sea level (msl), and the airplane descended about 1,000 ft before it recovered into a climb. The airplane then made a series of climbing turns until reaching 10,800 ft msl where it entered a second aerodynamic spin. The airplane did not recover from the second spin before it descended below available radar coverage at 6,800 ft msl (about 1,700 ft above the ground). Multiple witnesses reported seeing the airplane descending in a nose-down spin. One witness stated that the airplane completed about 5 turns in the spin before it descended behind a tree line into a reservoir. The airplane's Pilot Operating Handbook specified that at least 1,000 ft of altitude loss should be expected for a one-turn spin and recovery and that a six-turn spin and recovery may require more than twice that altitude loss because the airplane can develop a rapid rate of rotation and a steep nose-down pitch attitude. A postaccident examination revealed no evidence of a mechanical malfunction or failure that would have precluded normal operation during the flight. Additionally, the examination did not identify any foreign object debris that would have limited full movement of the flight controls during the flight, and the airplane's weight and balance were within the specified limits to conduct aerodynamic spins. It is likely that the pilots did not apply prompt and/or correct flight control inputs to adequately recover from the intentional aerodynamic spin.

The Larimer County Medical Examiner's Office, Loveland, Colorado, performed autopsies on the flight instructor and the pilot receiving instruction. The cause of death for both individuals was attributed to multiple blunt-force injuries sustained during the accident. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology tests on specimens obtained during each autopsy. The flight instructor's toxicology results were negative for carbon monoxide, ethanol, and all tested drugs and medications. The pilot receiving instruction's toxicology results detected dextromethorphan and its metabolite dextrorphan, doxylamine, and ibuprofen in urine. Dextromethorphan, dextrorphan, and doxylamine were also detected in blood at levels too low to quantify accurately. The testing also identified 35.75 µg/ml of acetaminophen in urine. Acetaminophen is a fever treatment and analgesic commonly available over the counter with the name Tylenol. Ibuprofen is also used to treat pain and fever and is commonly available over the counter with the names Advil and Motrin. Acetaminophen and ibuprofen are not considered impairing. Dextromethorphan is a cough suppressant found in many over the counter cough and cold preparations. In typical doses, dextromethorphan is not considered impairing. Doxylamine is a sedating antihistamine available in a variety of over the counter cold products and sleep aids. A postaccident review of available meteorological data established that day visual meteorological conditions prevailed at the accident site. The nearest aviation weather reporting station was located at Fort Collins-Loveland Municipal Airport (FNL) about 15 miles north-northeast of the accident site. At 0756, about 15 minutes after the accident, the FNL automated surface observing system reported wind 050° at 5 knots, 10 miles surface visibility, a clear sky, temperature -7°C, dew point -9°C, and an altimeter setting 29.68 inches of mercury. According to Federal Aviation Administration (FAA) records, the 58-year-old flight instructor held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. He also held a flight instructor certificate with ratings for airplane single-engine land and instrument airplane. His last aviation medical examination was on June 24, 2016, when he was issued a second-class medical certificate with a limitation to have glasses available for near vision. A search of FAA records showed no previous accidents, incidents, or enforcement proceedings. He was employed by McAir Aviation as the chief pilot in charge of flight instruction. On June 30, 2016, the FAA renewed his chief pilot authorization following an oral examination and checkride in a Cessna 172S. The operator reported that the flight instructor had a total flight experience of 6,678.5 hours. According to FAA records, the 23-year-old pilot receiving instruction held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. The commercial pilot certificate was issued on August 31, 2016. His last aviation medical examination was on January 6, 2015, when he was issued a third-class medical certificate with no limitations or restrictions. A search of FAA records showed no previous accidents, incidents, or enforcement proceedings. A pilot logbook was not recovered during the investigation; however, according to his father, the pilot receiving instruction had about 550 hours total flight experience of which about 400 hours had been flown during the previous year. The 2005-model-year airplane, serial number 172S10043, was a high-wing monoplane of aluminum semi-monocoque construction. The airplane was powered by a 180-horsepower, 4-cylinder, Lycoming IO-360-L2A reciprocating engine, serial number L-31665-51A. The engine provided thrust through a fixed-pitch, two-blade, McCauley model 1A170E/JHA7660 propeller, serial number ZF23025. The airplane was equipped with a fixed tricycle landing gear and wing flaps and had a certified maximum gross weight of 2,550 pounds. The FAA issued the airplane a standard airworthiness certificate on November 29, 2005. According to dispatch documentation, the airplane's hour meter indicated 6,053.7 hours before the flight. The airplane's hour meter indicated 6,054.2 hours at the accident site. At the time of the accident, the airframe had accumulated a total service time of 4,703 hours. The engine had accumulated a total service time of 5,994.6 hours since new and 1,862 hours since its most recent overhaul on December 21, 2012. The propeller had accumulated a total service time of 4,703 hours and 1,862 hours since its most recent overhaul on January 4, 2013. The last annual inspection of the airplane was completed on October 25, 2016, at 4,552.1 total airframe hours. A 100-hour inspection was completed on January 12, 2017, at 4,651.2 total airframe hours. The rudder return springs were replaced on January 24, 2017, at 4,668.8 total airframe hours. The rear bench seat and rear seat restraints were removed on February 13, 2017. A postaccident review of the maintenance records found no history of unresolved airworthiness issues. The airplane had two fuel tanks, one located in each wing, and a total fuel capacity of 56 gallons (53 gallons usable). According to dispatch records, the airplane departed with 27 gallons of fuel. The dispatch records included a weight-and-balance calculation worksheet for the flight. According to the worksheet, the combined weight of the flight instructor and the pilot receiving instruction was 325 pounds; the airplane departure weight was 2,173.5 pounds; and the calculated moment arm was 40.3 inches aft-of-datum. The postmortem weights of the flight instructor and the pilot-receiving-instruction were 204 pounds and 150 pounds, respectively. A postaccident weight-and-balance calculation, using the postmortem weights and a fuel consumption rate of 11 gallons per hour, established that the airplane was operating within the constraints of the utility category at the time of the accident. The airplane wreckage was found partially submerged in Culver Reservoir at an altitude of 5,142 ft msl. Airbags were used to float the airplane to the shore where it was subsequently recovered by a crane. All major structural components and flight controls remained intact. The aileron and flap control cables were disconnected at the wing root turnbuckles by the salvage company before the wings were removed for transport. The elevator and rudder cable circuits were not disconnected during wreckage recovery. The leading edge of the right wing was crushed upward and aft to the front spar about 45°. The leading edge of the left wing was crushed flat. The aft fuselage and tail cone were compressed on the right side and buckled slightly outward on the left side. The engine was compressed up and aft into the firewall. Aileron control cable continuity was established from the left and right aileron bell cranks to the center wing area where they had been disconnected to facilitate recovery of the wreckage. The aileron autopilot roll servo cables remained on the capstan and attached to the bell crank. The aileron cables remained installed on the left and right control column sprockets and were wrapped around the interconnect pulley. A measurement of the wing flap actuator was consistent with the flaps being fully retracted at impact. Elevator control cable continuity was established from the forward elevator bell crank to the aft elevator bell crank. The forward elevator bell crank was bent due to floor compression damage that was sustained during impact. The elevator autopilot pitch servo cables were on the capstan, and the bridal cables remained attached to the control cable. Rudder control cable continuity was established from the rudder torque tubes to the rudder horn. The rudder stops exhibited normal wear signatures. The r