History of Flight
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 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 flight instructor stated that he received text messages from the pilot asking, “Tricks for starting the cirrus in the cold?” and stating that the pilot flooded the engine and there was fuel on the ground. An additional message stated that the FBO was taking “forever” to get a ground power unit (GPU). After FBO personnel connected a GPU, the pilot then started the airplane’s engine after five additional attempts.
A witness, who was inside the FBO, said once the accident airplane’s engine started, the GPU was disconnected, the wheel chock was removed, and within two minutes the accident airplane started taxiing and turned onto taxiway A. He said that the pilot of the airplane did not allow the engine to warm after engine start and before taxiing. He said that typically on cold days, he must wait at least 6–8 minutes before taxiing his airplane. He did not know if the pilot of the accident airplane performed a run-up before departure. He said he did not think enough time had elapsed from the time the accident airplane’s engine was started to the time of the accident for the engine oil to have warmed up enough.
The flight took off from runway 4L and reached a maximum altitude of about 425 ft mean sea level (msl); the airport elevation was 266 ft msl. During the departure climb, the pilot transmitted that he lost the engine. The airplane entered a right bank, descended, and impacted the ground near the airport fire station.
Personnel Information
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.
Aircraft Information
The airplane was powered by a 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 160–180°F; 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 Supplemental Type Certificate (STC). The Tornado Alley Flight Manual supplement provided a turbocharger system description, which stated that the absolute controller and wastegates work in conjunction to provide proper boost pressure. The wastegate is actuated using engine oil pressure to actuate a small hydraulic cylinder which redirects the engine bypass 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. The Tornado Alley Flight Manual supplement specified changes to some of these limitations; the oil temperature limitation was unchanged. The 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.
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 No. 1, Revision No. 2, which states that it 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.
Wreckage and Impact Information
The airplane was destroyed by impact forces and a postcrash fire. The wreckage path preceded the main wreckage on a southerly track and contained two of three propeller blades; the third propeller blade was located about 100 ft west of the initial impact point. The propeller blades were separated near their blade roots, exhibited damage consistent with overload separation and had chordwise scratches consistent with rotation.
A foreign object debris check of runway 4L and its runway edges revealed no parts or pieces associated with the airplane. Postaccident examination of the flight control system confirmed flight control continuity. The wing flaps were in the retracted position.
Examination of the engine did not reveal any anomalies that would have precluded operation. However, the engine and most of the engine accessories sustained accident-related impact and thermal damage, which precluded functional testing at the system and component level.
Flight Recorders
The airplane was equipped with a crash-hardened data storage unit installed in the tail. The unit recorded flight, engine, and autopilot parameters. Data was logged once per second and stored inside the crash-hardened enclosure.
Recorded data showed 18 engine start attempts, with the last occurring about 1302:00, which was then followed by sustained engine operation at 1,000–1,200 rpm until the beginning of takeoff. About 1313:16, engine oil temperature reached 100°F, and the accident takeoff began about 1315:25. From engine start to takeoff, there was no engine rpm increase to 1,700 rpm, consistent with an engine run-up as prescribed in the Cirrus SR22 Pilot’s Operating Handbook and FAA Approved Flight Manual before takeoff checklist.
About the beginning of takeoff, oil temperature and pressure were 108°F and 47 psi, respectively. After takeoff, the following maximum engine parameters were attained: fuel flow of 37.9 gallons per hour, manifold pressure of 32.5 inches of mercury, and oil pressure of 58 psi. The engine oil temperature at this time was 115°F and the GPS altitude was 393 ft. The increases and decreases in engine parameter values were positively correlated. Following these maximum values, there was a general decay in engine parameter values. A stall warning, which began at a GPS altitude of 433 ft, was recorded during the last five seconds of the recording.
Medical and Pathological Information
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. The pilot was issued a second-class medical certificate limited by a requirement to use corrective lenses to meet vision standards.
FAA Forensic Sciences Laboratory postmortem toxicological testing detected diphenhydramine in heart blood at a low level (less than 12.5 ng/mL) and in urine at 207 ng/mL. Postmortem testing measured elevated glucose of 813 mg/dL in urine; vitreous glucose was 58 mg/dL. Hemoglobin A1c (HbA1c) was elevated at 9.1% in heart blood.
Diphenhydramine is a sedating antihistamine medication. The FAA states that pilots should not fly within 60 hours of using diphenhydramine. In a typical living person, the elimination half-life of diphenhydramine is about 3–14 hours. One small study estimated that drowsiness may occur at plasma concentrations above about 30–40 ng/mL, and mental impairment may occur above about 60 ng/mL. Comparing diphenhydramine concentrations in postmortem blood to established ranges in living individuals must be done cautiously because of potential postmortem redistribution.
Glucose is the main sugar that provides energy to the body. HbA1c is an indirect measure of average blood glucose over about the preceding 3 months; HbA1c of less than 5.7% is considered normal, while 6.5% or higher diagnoses diabetes. HbA1c of 9.1% corresponds to an estimated average blood glucose of 214 mg/dL.
Tests and Research
The FAA Airplane Flying Handbook (FAA-H-8083-3C), Chapter 18: Emergency Procedures, Engine Failure After Takeoff (Single-Engine), states that continuing straight ahead or making a slight turn gives the pilot time to establish a safe landing attitude, and the landing occurs under control and as slowly as possible. Turning back requires a more complex analysis and consideration of risk.
The NTSB conducted a review of available publications, in addition to the Tornado Alley Flight Manual, to determine information discussing cold oil temperature effects on turbocharging control systems. The FAA Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7, discusses turbocharged engine overboost but does not address the associated fuel mixture becoming excessively rich due to cold oil temperatures. The FAA Aviation Maintenance Technician Handbook – Powerplant (FAA-H-8083-2) discusses turbocharger systems but does not discuss effects of cold oil temperature on overboost and fuel mixture. Continental Aircraft Engine Service Bulletin M67-12 discusses overboost of Continental turbocharger systems without reference to the effects of rich mixture.