ERA23FA113

The pre-ignition/detonation damage to the No. 4 piston for reasons that could not be determined, which allowed the crankcase to become pressurized and resulted in oil exhaustion and subsequent catastrophic internal engine failure.

About 18 minutes after takeoff, while on an instrument flight rules (IFR) flight, the pilot requested a lower altitude, advising the controller that the airplane’s climb performance was degraded. As the flight continued the pilot recognized a “dead cylinder” and requested a heading to a nearby airport. The controller vectored the flight to the airport, but the pilot delayed turning onto the vectored heading for over 2 minutes. When the flight was about 6 nautical miles from the airport the pilot declared an emergency and advised the controller that the oil pressure was dropping. After turning onto the vectored heading, the airplane began a right turn that was not directed by the controller or announced by the pilot. The controller informed the pilot to level the wings and maintain 5,000 ft msl. The change in the airplane’s heading resulted in the controller providing a new vector, which increased the distance and flight time to the intended runway. Recorded data showed the engine then lost all power. The airplane continued to descend and subsequently collided with trees and the ground less than 1 mile from the intended runway threshold. According to recorded data, shortly after takeoff, when the flight was about 1 nautical mile from the departure end of the runway, the No. 4 cylinder head temperature (CHT) value exceeded the highest allowed value. The flight continued while the No. 4 CHT continued to increase. The CHT for that cylinder then began to decrease, consistent with non-firing of the fuel air mixture, and the flight continued. Postaccident examination of the engine revealed damage to the top and sides of the No. 4 piston that were likely the result of pre-ignition/detonation that pressurized the crankcase, pushing oil out of the breather assembly and depleting the oil supply. This ultimately resulted in oil exhaustion and subsequent catastrophic internal engine failure. Both spark plugs of the No. 4 cylinder had extensive deposits and one had a separated section of core nose insulator while the other only had a cracked core nose insulator, though it could not be determined from the available evidence if those conditions existed before or were the result of pre-ignition/detonation. Causes for detonation include improper ignition timing, high inlet air temperature, engine overheating, carbon build-up or oil in the combustion chamber, an issue with the fuel octane, or a lean fuel-to-air mixture. Although the magneto-to-engine timing could not be determined postaccident, there were no postaccident anomalies noted with either the magneto or the ignition harness. High inlet air temperature, engine overheating, or carbon build-up/oil in the combustion chamber were not likely or not observed. There was no report of any fuel-related issue from the facility that last fueled the accident airplane. While the position of the mixture control during the flight and the pilot’s leaning procedures were unknown, it is unlikely that the pilot would have leaned the fuel-to-air ratio to CHT exceedance as that would have been contrary to the published limitations and takeoff procedures.

A High Resolution Rapid Refresh (HRRR) model sounding was created for the accident time and location, with the modeled surface elevation at 423 ft msl. Based on the sounding, the freezing level was around 9,500 ft msl with the sounding temperature and dew point of -0.3°C at 9,534 ft msl. The HRRR indicated that the winds aloft at about 6,000 ft msl were from 231° at 48 knots. A review of the pilot’s logbook that began with his 1st logged flight in May 2013 and his last logged flight on December 2, 2022., revealed that including the date of a flight associated with his instrument rating received on May 29, 2017, he logged a total of 3.0 hours actual instrument flight time and 50.5 hours simulated instrument flight time. Since obtaining his instrument rating, he logged about 9 hours of actual instrument flight time and 29 hours of simulated instrument time. His last logged instrument proficiency check flight occurred on October 3, 2021. In August 2022, he flew 5 flights with a flight instructor, logging “holds” and performing a total of 17 instrument approaches and accruing 1.5 hours of actual instrument flight time and 4.4 hours of simulated instrument flight time. His last logged actual instrument flight of 0.2 hour occurred on November 3rd/4th 2022, while his last logged simulated instrument flight time of 2.0 hours occurred on December 2, 2022. The airplane underwent modifications in accordance with (IAW) Supplemental Type Certificates (STC) covering installation of a different model engine and propeller, overhaul and calibration of the manifold pressure/fuel flow gauge, installation of new cooling air baffles, aileron and wing flap gap seals, and lower cowling access panels. Section II, Limitations, of the POH/AFM specified that the maximum CHT was 460°F, and the minimum oil pressure was 30 psi. Section III, Emergency Procedures, of the POH/AFM revealed there were no checklists for loss of oil pressure or CHT exceedance. The engine manufacturer Standard Practice Maintenance Manual specified that the fuel flow at full power be between 24.9 to 26.6 gallons-per-hour (GPH). Two mobile phones, a tablet computer, two Garmin G5’s, and a Stratus Attitude Heading and Reference System (AHRS) were recovered from the wreckage. No data were recovered from either mobile phone, the tablet computer, or either Garmin G5. An Insight GEM which was installed in the instrument panel, just above and to the right of the center control yoke, in accordance with installation instructions that specified it was to be installed where it was easily visible by the pilot. Data were successfully recovered from the device following the accident. Further review of the GEM data associated with the accident flight, correlated with ADS-B data, revealed that the recorded fuel flow values from about takeoff power application to when it decreased and remained at 0 were nearly always above the maximum limit of 26.6 GPH, averaging about 44 GPH with the highest value slightly over 99 GPH. The EGT values, which were not an engine operating limitation, appeared “noisy” and erratic for the No. 4 cylinder and had not trended with the remaining cylinders since December 13, 2022. The oil temperature values from takeoff power application to where the fuel flow decreased to and remained at 0 were above normal, averaging about 693°F. Data from the GEM for the flight before the accident flight revealed that the CHT values for the No. 4 cylinder were generally equal to or slightly higher than the highest values for the remaining cylinders; however, all CHT readings were below the maximum specified value. The data also indicated that the fuel flow was generally steady and within limits except for a short period about 5 minutes after takeoff power was applied, periodically during the flight, and then again for about 19 minutes before power was reduced. During the times when the fuel flow was erratic and exceeded the maximum specified value, the CHT values for all cylinders were below the maximum value and all trended generally the same. The oil temperature values from takeoff power application to the end of recorded data were above normal, averaging about 1,714°F (these recorded values were likely erroneous). The engine was rebuilt by Continental Aerospace Technologies (formerly Teledyne Continental Motors) on September 13, 2019, then installed into the accident airplane on November 22, 2019 at tachometer time of 835.34 hours. The engine remained installed to the accident date. An engine maintenance logbook entry dated January 18, 2022, at tachometer time of 1,462.5, indicated that the top and bottom spark plugs of the No. 4 cylinder were removed and replaced with new plugs. The last 100-hour inspection of the engine was performed on November 9, 2022, at tachometer time 1809.6, and the last oil change occurred on December 16, 2022, at tachometer time 1871.3. At the time of the accident, the tachometer was reading 1889.21 hours. Thus, the engine had accrued about 18 hours since the last oil change, 80 hours since the last 100-hour inspection, 427 hours since the No. 4 top and bottom spark plugs were replaced, and 1,054 hours since major overhaul. The stockholder of the airplane reported flying it for 12.8 hours during the two days before the accident. He reported he normally operated the airplane at 23 inches of manifold pressure and 2,400 rpm and leaned the fuel-to-air ratio to about 25° rich of peak. He was not sure how the accident pilot flew the airplane with respect to his leaning procedures. He reported no engine related issues during his flights. Earlier on the accident date before the flight departed from CGF, he added one or one and a half quarts of oil to the engine, which brought the total capacity to 10.5 quarts; the full capacity was 12 quarts. On the accident date the airplane was fueled with 39.2 gallons of 100 low-lead fuel, which filled each main fuel tank. According to the facility that provided the fuel, there were no fuel-related complaints from aircraft that purchased fuel before the accident airplane. Specific gravity testing was performed postaccident and the results were within 0.2 of the value when the fuel was delivered two days before the accident. According to an FAA Safety Team (FAAST) presentation regarding preignition and detonation, detonation is an explosion of the fuel/air mixture inside the cylinder and occurs near or after top dead center. It causes the fuel/air charge to explode rather than ignite smoothly. Because of the explosion the charge exerts a much higher force on the piston and cylinder, causing a reduction in power. The presentation further indicated that detonation can be caused by improper ignition timing, high inlet air temperature, engine overheating due to bent baffles, or oil or carbon build-up in the combustion chamber. The presentation recommended prevention by cooling the engine by reducing power, increasing airspeed, enrichening the mixture, and opening the cowl flaps. Internal postmortem examination of the pilot was not performed due to religious concerns. According to the Office of the Medical Examiner, County of Westchester, New York, the cause of death was multiple blunt force trauma, and his manner of death was accident. The Westchester County Department of Labs and Research, Division of Forensic Toxicology, performed toxicological testing of postmortem urine and subclavian blood from the pilot. 7-aminoclonazepam was detected in blood at 24 ng/mL and in urine at less than 125 ng/mL. Clonazepam was not detected. Sertraline, acetaminophen, salicylic acid, and naproxen were presumptively detected in blood. Forensic toxicology was performed by the FAA Forensic Sciences Laboratory, Oklahoma City, Oklahoma, on specimens of the pilot obtained from syringe only. 7-aminoclonazepam was detected in subclavian blood at 25 ng/mL and urine at 94 ng/mL. Sertraline was detected in blood at 78 ng/mL and was also detected i