CEN24FA095

The pilot’s failure to maintain airplane control after a partial loss of engine power during initial climb. Contributing to the accident was the pilot’s failure to follow airplane flight manual procedures and limitations for the turbocharged engine, which resulted in a loss of engine power due to cold weather effects on the turbocharger control system.

The pilot planned on flying the airplane on a personal cross-country flight. The air temperature at the departure airport was about 28°F when the pilot attempted to start the airplane engine for the flight. There were an excessive number of engine start attempts by the pilot, which he attributed to the cold weather and flooding the engine. Once he started the engine, he immediately taxied the airplane without allowing the engine to warm up. Recorded data showed that an engine run-up was not performed as prescribed in the airplane’s before takeoff checklist. Recorded data also showed the engine oil reached its minimum temperature limit about 11 minutes after engine start, which was about 2 minutes before the start of takeoff. During the departure climb, the engine manifold pressure exceeded its maximum limitation, the fuel flow entered its caution range, and oil pressure was near its upper normal range limit, all of which were indicative of the viscous effects of cold oil, which induced an excessively rich mixture. The pilot then reported that the engine lost power, and recorded data showed that engine power and airspeed gradually decreased. The airplane then entered an aerodynamic stall, descended, and impacted an area next to the departure runway. Postaccident examination of the airplane did not reveal any anomalies that would have precluded normal operation. The engine had been modified through a supplemental type certificate (STC) with the installation of a turbocharging system. There was no change in engine oil temperature limits with the installation of the turbocharger but there were changes in fuel flow and oil pressure limits. The STC flight manual supplement stated that if manifold pressure exceeded normal limits, engine throttle should be reduced. The supplement further stated that engine parameters should read in the green during takeoff and noted that manifold pressure may temporarily increase with an associated increase in fuel flow due to cooler oil temperatures. The pilot completed training in the airplane about 10 days before the accident, during which he accumulated 10 hours of flight time. The pilot’s total experience flying airplanes powered by turbocharged engines was unable to be determined. The pilot’s postmortem toxicology results indicate that he had used the sedating antihistamine medication diphenhydramine. The level of diphenhydramine in postmortem heart blood was low. Based on this result, it is unclear whether the pilot was experiencing any impairing effects of his diphenhydramine use at the time of the accident or during earlier flight-related activities. The pilot’s high HbA1c indicates that he had uncontrolled diabetes, which was not identified at his last aviation medical examination. Additionally, the pilot had a history of high blood pressure that was associated with some increased cardiovascular risk, and his autopsy results indicate the presence of at least mild cardiovascular disease. However, neither the toxicological nor the autopsy evidence provide any clear, specific indication that the pilot was significantly impaired by his medical conditions.

The investigation was unable to locate any logbooks that showed the pilot’s total experience flying turbocharged airplanes. A flight instructor provided a statement for the pilot’s airplane insurance application attesting that he provided the pilot with ground instruction and 10 hours of flight training, including 10 takeoffs and landings, in the airplane on October 3 and 17, 2023, and on January 4 and 11, 2024. The pilot reported on the application that he had logged 15.2 hours in a Cirrus SR22. The pilot’s estimated total flight times were based upon the insurance application. The airplane was powered by Teledyne Continental Motors model IO-550-N, fuel-injected, direct drive, air-cooled, horizontally opposed, 6-cylinder, 550 cubic inch displacement engine, rated at 310 horsepower. IO-550-N engines are equipped with non-congealing oil coolers that have a vernatherm (bypass) valve, which directs oil into the oil cooler when the engine warms up to about 160–180oF; otherwise, oil is routed around the cooling fins and into the oil cooler galley. The engine was modified by the addition of a Tornado Alley Turbonormalizing System, through a STC. The Tornado Alley Flight Manual supplement provided a turbocharger system description, which stated: The absolute controller and wastegates work in conjunction with each other to provide proper boost pressure to the engine. The wastegate is actuated using engine oil pressure to actuate a small hydraulic cylinder which redirects the engine by-pass exhaust flow around the turbochargers. The absolute pressure controller utilizes an aneroid bellows and spring connected to a valve that regulates the amount of oil flowing out of the wastegate actuator hydraulic control cylinder. The aneroid bellows are located inside a housing that is connected to the output air produced by the compressors. The control lines for the turbocharger system were connected to the oil cooler galley, and the engine oil temperature sensor was connected to the oil output of the oil cooler. In the Tornado Alley Turbo Continued Airworthiness Manual for Cirrus Design SR22 Series Airplanes Turbonormalized per STC’s SA10588SC and SE10589SC, the post-engine overhaul/installation instructions noted that target fuel flow is achieved with an engine oil temperature not less than 170°F. The Cirrus SR22 Pilot’s Operating Handbook and FAA Approved Flight Manual list engine and fuel limitations for SR22 airplanes not certified with a turbocharged engine, as shown in figure 2. Figure 2. Cirrus SR22 engine limitations (top) and fuel limitations (bottom). The Tornado Alley Flight Manual supplement specified changes to some of these limitations, as shown in figure 3. The oil temperature limitation was unchanged. Figure 3. Tornado Alley flight manual supplemental limitations. The Tornado Alley Flight Manual supplement added steps to Cirrus’s SR22 takeoff procedures, stating that engine parameters should read in the green during takeoff and manifold pressure may temporarily increase to 31–32 inches of mercury with an associated increase in fuel flow due to cooler oil temperatures. If the manifold pressure exceeded 32 inches of mercury, then the corrective response was to reduce power, shown in Figure 4. Figure 4. Tornado Alley flight manual supplemental procedures. The Tornado Alley Flight Manual supplement did not have a section for turbocharger emergency procedures as specified in the General Aviation Manufacturers Association (GAMA) Specification for Pilot’s Operating Handbook (GAMA Specification No. 1, Revision No. 2, October 18, 1996), which states that Revision No. 2 “incorporates NTSB suggestions for inclusion of emergency procedures for supercharger/turbocharger failure” and that “procedures shall be provided for coping with emergencies involving” turbocharger systems. Manufacturers may use GAMA Specification No. 1 to fulfill the aircraft flight manual requirements in 14 CFR Part 23. The Arkansas State Crime Laboratory performed an autopsy of the pilot. According to the autopsy report, the cause of death was multiple injuries, and the manner of death was accident. The pilot’s autopsy identified mild coronary artery and aortic plaque. The heart was described as appearing mildly enlarged. Visual examination of the heart did not identify other significant disease. The pilot’s last aviation medical examination was on April 6, 2023. At that time, he reported a history of high blood pressure, which was noted to be qualified under Conditions Aviation Medical Examiners Can Issue (CACI) criteria. The pilot reported using lisinopril and nebivolol, which are prescription medications that can be used to treat high blood pressure. The choice of nebivolol for treatment of high blood pressure sometimes is prompted by the presence of other cardiovascular conditions, but no such conditions were reported. The pilot was issued a second-class medical certificate limited by a requirement to use corrective lenses to meet vision standards at all required distances. FAA Forensic Sciences Laboratory postmortem toxicological testing detected diphenhydramine in heart blood at a low level (less than 12.5 ng/mL, according to an FAA forensic toxicologist) and in urine at 207 ng/mL. FAA Forensic Sciences Laboratory postmortem testing measured elevated glucose of 813 mg/dL in urine. (The laboratory considers values above 100 mg/dL to be abnormal.) Vitreous glucose was measured at 58 mg/dL. (The laboratory considers values above 125 mg/dL to be abnormal.) Hemoglobin A1c (HbA1c) was elevated at 9.1% (normal is less than 5.7%) in heart blood. Diphenhydramine is a sedating antihistamine medication widely available over the counter in multiple sleep aids and cold and allergy products. Diphenhydramine can result in cognitive and psychomotor slowing and drowsiness and often carries a warning about driving and operating machinery. The FAA states that pilots should not fly within 60 hours of using diphenhydramine, to allow time for it to be cleared from circulation. In a typical living person, the elimination half-life of diphenhydramine is about 3–14 hours, and the concentration of the drug in plasma is about 1.3 times that in blood. One small study of healthy adult males estimated that drowsiness may occur at plasma diphenhydramine concentrations above about 30–40 ng/mL, and mental impairment may occur at plasma diphenhydramine concentrations above about 60 ng/mL. Comparing diphenhydramine concentrations in postmortem blood to established ranges in living individuals must be done cautiously, because diphenhydramine has significant potential for postmortem redistribution. Glucose is the main sugar that provides energy to the body. HbA1c is an indirect measure of a person’s average blood glucose over about the preceding 3 months; HbA1c of less than 5.7% generally is considered normal, while HbA1c of 6.5% or higher diagnoses diabetes. HbA1c of 9.1% corresponds to an estimated average blood glucose over the prior few months of 214 mg/dL. For many adults with diabetes, recommended pre-meal blood sugars are between 80 mg/dL and 130 mg/dL, and recommended peak after-meal blood sugars are less than 180 mg/dL. On January 21, 2024, at 1320 central standard time, a Cirrus SR22, N255JP, was destroyed when it was involved in an accident near Little Rock, Arkansas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The airplane was kept in an unheated hangar at Bill and Hillary Clinton National Airport/Adams Field (LIT), Little Rock, Arkansas. On the day of the accident, the pilot called a fixed-base operator (FBO) at LIT to move the airplane outside; at the time, the outside air temperature was about 28°F. When the pilot arrived, he attempted to start the airplane’s engine fourteen times, then ceased further attempts because the battery died. The pilot’s fl