History of Flight
On January 19, 2023, about 1729 EST, a Beech A36, N19MT, was substantially damaged when it was involved in an accident near North Castle, New York. The private pilot and one passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
According to ADS-B and air traffic control audio information, the flight departed from runway 4L at John F Kennedy International Airport (JFK), New York, at 1658, and continued on a north-northeast heading. After takeoff, data from the on-board Graphic Engine Monitor (GEM) indicated the cylinder head temperature (CHT) value for the No. 4 cylinder was generally higher than the values for the other cylinders but all were within normal limits until 1659:23. At that time, the No. 4 CHT value indicated 463°F, above the maximum red line value of 460°F. The CHT values for the No. 4 cylinder continued increasing, reaching a maximum of 711°F at 1700:39 and then falling below the CHT values for the remaining cylinders, which were normal.
The flight continued with normal communications until 1710:15, when the pilot advised the controller he was “doing his best” in response to the instruction to maintain best rate of climb to 8,000 ft. At 1715:54, the pilot asked to stop the climb at 6,000 ft. The controller approved, and the pilot reported poor aircraft performance, climbing only about 200 feet per minute. At 1716:54, the pilot reported nothing on instrumentation to explain the poor climb. The controller suggested proceeding to Westchester County Airport (HPN). At 1718:30, the pilot reported a “dead cylinder” and requested to proceed to HPN. At 1719:52, the controller asked if he was declaring an emergency; the pilot replied he was not. At 1720:11, GEM data indicated oil pressure decreased below the minimum specified value of 30 psi and continued to 0 psi. At 1721:18, the pilot declared an emergency and reported oil pressure dropping. After a series of communications, at 1725:13, the pilot broadcast “mayday mayday mayday.” At 1725:46, engine rpm and fuel flow read zero. At 1728:56, radar contact was lost. Multiple agencies located the wreckage at 2255.
Personnel Information
Review of the pilot’s logbook from his first flight in May 2013 to his last flight on December 2, 2022 revealed 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 on May 29, 2017, he logged about 9 hours actual instrument and 29 hours simulated instrument. His last instrument proficiency check was on October 3, 2021. In August 2022, he flew 5 flights with a flight instructor, performing 17 instrument approaches and accruing 1.5 hours actual instrument and 4.4 hours simulated instrument. His last actual instrument flight of 0.2 hour occurred on November 3/4, 2022, and last simulated instrument flight of 2.0 hours on December 2, 2022.
Aircraft Information
The airplane underwent modifications per Supplemental Type Certificates (STC) covering installation of a different engine and propeller, overhaul of the manifold pressure/fuel flow gauge, installation of cooling air baffles, aileron and wing flap gap seals, and lower cowling access panels. Section II of the POH/AFM specified maximum CHT 460°F and minimum oil pressure 30 psi. Section III contained no checklists for loss of oil pressure or CHT exceedance. The engine manufacturer specified fuel flow at full power between 24.9 and 26.6 GPH.
Two mobile phones, a tablet, two Garmin G5s, and a Stratus AHRS were recovered but no data were retrieved from them. An Insight GEM installed in the instrument panel provided data. GEM data from the accident flight showed fuel flow values from takeoff to when it decreased to zero were nearly always above the maximum limit, averaging about 44 GPH with highest over 99 GPH. The No. 4 cylinder EGT values were “noisy” and erratic since December 13, 2022. Oil temperature values averaged about 693°F. Data from the previous flight showed No. 4 CHT values generally equal to or slightly higher than others, but below maximum; fuel flow was generally steady except for short periods. Oil temperature values averaged about 1,714°F (likely erroneous).
The engine was rebuilt by Continental Aerospace Technologies on September 13, 2019, and installed on November 22, 2019. The last 100-hour inspection was on November 9, 2022, and last oil change on December 16, 2022. At the accident, tachometer read 1889.21 hours, meaning about 18 hours since oil change, 80 hours since 100-hour inspection, 427 hours since No. 4 spark plug replacement, and 1,054 hours since major overhaul. The stockholder reported flying 12.8 hours in the two days before the accident, normally operating at 23 inches manifold pressure and 2,400 rpm, leaning to about 25° rich of peak. Earlier on the accident date, he added one to one and a half quarts of oil, bringing total to 10.5 quarts (full capacity 12 quarts). The airplane was fueled with 39.2 gallons of 100 low-lead fuel; specific gravity testing was within 0.2 of the delivery value.
According to an FAA Safety Team presentation on preignition and detonation, detonation causes the fuel/air charge to explode, resulting in higher force on piston and cylinder and reduction in power. Causes include improper ignition timing, high inlet air temperature, engine overheating due to baffle issues, or oil/carbon buildup. Prevention includes cooling the engine by reducing power, increasing airspeed, enrichening mixture, and opening cowl flaps.
Meteorological Information
A High Resolution Rapid Refresh (HRRR) model sounding for the accident time and location with modeled surface elevation 423 ft msl indicated the freezing level around 9,500 ft msl, with temperature and dew point -0.3°C at 9,534 ft. Winds aloft at about 6,000 ft were from 231° at 48 knots.
Wreckage and Impact Information
Initial impact marks began in a tree about 100 ft above ground level (agl). Multiple tree contacts at decreasing heights were noted along the energy path, which was 250 ft long on a magnetic heading of 179°. The accident site was about 0.8 nautical mile and 301° from the approach end of runway 16. The main wreckage (fuselage with aft empennage and 4-ft inboard left wing section) came to rest wedged near two trees. Separated wing sections, engine without propeller, and propeller were located nearby. Control surfaces remained attached; flight control cable continuity was confirmed. Landing gear was retracted; aileron cables showed tension overload with no preimpact failure. Flap actuators equated to flaps retracted.
Fresh oil was noted on the bottom of the fuselage from wing leading edge to tail cone, appearing to come from behind the left cowl flap area. The crankcase breather tube outlet contained fresh oil. The cockpit control yokes and seats were separated but in the vicinity. The throttle control was 1/4 inch from full forward; mixture and propeller controls were full forward; cowl flap handle extended (open) and bent. The separated engine had a hole in the crankcase above the No. 6 cylinder position; a deformed connecting rod cap with two fractured bolts was found inside. Minimal oil remained in the oil sump; damage to connecting rod bearings and rods was consistent with oil exhaustion. The No. 4 cylinder spark plug heli-coils were properly installed; the No. 4 piston showed erosion damage consistent with pre-ignition/detonation, producing a gap between piston side and compression rings. The air induction system for No. 4 had no preimpact failure. Fuel injector components passed operational testing except one impact-damaged nozzle. The engine-driven fuel pump, after removal of internal contamination, tested with discharge pressure slightly above limits. The throttle body and metering valve at full throttle flowed about 1 lb/hr above maximum. Magnetos functioned normally, but magneto-to-engine timing could not be determined. No. 4 ignition leads passed high-tension testing despite chafing. The No. 4 spark plugs showed extensive material at the firing end and were sent for examination.