CEN24FA179

The pilot’s exceedance of the airplane’s design limitations, which resulted in an in-flight breakup.

The pilot departed about 1721 central daylight time (all times CDT unless otherwise noted) on an instrument flight rules cross-country flight with one passenger and two dogs. After departure, the airplane turned onto a northwesterly track toward the destination. The pilot requested flight level (FL) 280 and, at 1841, reported to air traffic control (ATC) that his satellite weather radar was not functioning; he later asked for assistance navigating through weather. At 1908, he reported light chop over the previous 40 miles but that the flight was currently smooth. At 1944, ATC instructed the pilot to descend to FL 240 and the pilot then checked in with a new ATC center on his route and reported descending with moderate chop. ATC responded by instructing the pilot to descend at his discretion to 17,000 ft msl (all altitudes in msl unless otherwise noted). The airplane reached FL 240 (the previously instructed altitude) at 1949, where it stayed for less than a minute before continuing its descent. The first portion of this descent was at a rate of 2,000 ft/min before slowing to about 1,000 ft/min. At 1954, while the airplane was descending through 20,000 ft, ATC instructed the pilot to descend at his discretion to 6,000 ft. The airplane’s rate of descent increased to more than 3,000 ft/min, and the airspeed markedly increased from 170 kts to over 200 kts, exceeding the airplane’s maximum operation limit of 187 kts calibrated airspeed; the airplane was at risk of structural damage when exceeding this limitation. Data showed that the airplane’s descent then arrested about 18,000 ft (which ADS-B data recorded as the selected altitude) and it began a small climb as the airplane’s airspeed began to slow below 170 kts. At the same time, the airplane began a slight right turn off of its original course that was consistent with the airplane no longer under autopilot control. Twenty seconds later, the airplane began to rapidly descend in a tightening right turn while the calibrated airspeed rapidly increased, again surpassing the maximum operation limit. ATC simultaneously lost communication and radar contact with the airplane at 7,800 ft msl. The controller attempted to contact the pilot with no response. ATC then issued an alert notification (ALNOT) and a search began. Weather radar imagery showed the airplane encountering light intensity echoes as it descended from 24,000 ft consistent with instrument meteorological conditions. Based on the temperature profile, the cloud droplets and precipitation were in a supercooled liquid state that put the airplane at risk of structural icing. However, the airplane was equipped with deicing boots, and the performance study data showed no increase in the airplane’s drag, which was indicative of ice accumulation, before the airplane’s departure from straight flight. The airplane sustained structural damage during at least one of the airspeed exceedances and eventually broke apart in flight. The wing spar box signatures and fuselage witness marks from contact with the wing leading edge de-ice boots suggested positive wing loading before the in-flight breakup. The left horizontal stabilizer, vertical stabilizer, rudder, elevator, right aileron, right flap, and the outboard portion of the right wing were not located at the accident site and likely separated as a result of the in-flight breakup. The pilot would not have had out-of-cockpit visual reference for the majority of the end of flight. The investigation considered the possibility that the pilot experienced spatial disorientation after taking control of the airplane from the autopilot during the descent. Although the tightening turn is consistent with a loss of control due to spatial disorientation, the pilot had over 1,300 hours of actual instrument flight experience and likely would have been aware of the possibility of such illusory effects. Additionally, the lowest cloud bases were about 10,000 ft which would have given the pilot a small amount of time to regain orientation if he had become disoriented. It is possible that the airplane’s deviation from the intended track (indicative of the airplane no longer under autopilot control), whether pilot induced or not, was the result of a structural failure. Analysis of weather sounding data also indicated strong vertical wind shear between 13,000 ft and 16,000 ft and a high possibility of moderate or greater turbulence within those altitudes. Accordingly, the investigation also considered the possibility that the airspeed exceedances during the descent, combined with the moderate and greater turbulence forecast for the area just below the airplane’s flight path, resulted in structural damage to the airplane that rendered it uncontrollable. Given that the loss of control happened within about 20 seconds from the time the airplane deviated from its flight path (no longer under autopilot control) and that the pilot (who was experienced in actual instrument conditions) was not able to recover airplane control, the airplane likely sustained airframe damage from the airspeed exceedances during the descent that prevented the pilot or autopilot from maintaining control. A medical review revealed the pilot’s coronary artery disease was associated with some increased risk of an impairing or incapacitating cardiovascular event such as chest pain, abnormal heartbeat, or heart attack. Although such an event does not leave reliable autopsy evidence if it occurs immediately before death, there is no autopsy evidence that such an event occurred. Additionally, the pilot’s postmortem toxicology results indicate that he had used phentermine. The phentermine results in postmortem urine and tissue provided no clear evidence that the pilot was experiencing significant associated impairing effects at the time of the accident.

The pilot had recorded over 1,300 hours of actual instrument flight time and about 6 hours of actual instrument time in the 90 days before the accident. According to the airplane’s Pilot’s Operating Handbook and FAA-Approved Flight Information Manual, the maximum operating maneuvering speed was188 kts indicated airspeed, or 187 kts calibrated airspeed. According to the airplane manufacturer, the airplane’s autopilot will not disconnect unless there is a system failure or pilot action. An autopsy of the pilot was performed by the Arkansas State Crime Laboratory. According to the autopsy report, the cause of death was multiple traumatic injuries, and the manner of death was accident. The pilot’s autopsy identified 50% narrowing of the right coronary artery by soft plaque. Visual examination of the heart did not identify other significant disease. The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem specimens from the pilot. Testing was positive for phentermine. Phentermine is an amphetamine derivative used as a short-term adjunct with diet modification and exercise to increase weight loss. Phentermine is an appetite suppressant, can cause irregular heartbeats and delirium, and generally carries a warning that use may impair the ability to operate a motor vehicle or operate heavy machinery. Phentermine also carries a warning regarding the risk of abuse as it is a stimulant, and its use may also contribute to insomnia due to its stimulant effects. Phentermine’s effects last 12-14 hours per dose and may be detected in urine for 2-4 days after the last dose taken. Phentermine is disqualifying for pilots and was not reported at the pilot’s most recent medical examination. On May 12, 2024, about 1956 central daylight time, a Piper PA46-500TP airplane, N241PM, was substantially damaged when it was involved in an accident near Marianna, Arkansas. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot filed an instrument flight rules flight plan from the Pensacola International Airport (PNS), Pensacola, Florida, to Batesville Regional Airport (BVX), Batesville, Arkansas. A review of FAA-provided flight track data revealed that the flight departed PNS about 1721, turned to the northwest, and climbed to FL 280. The airplane’s course was a direct line to BVX. About 1945, the pilot began a descent out of FL 280. About 1955, the airplane entered a rapid descent and spiraling right turn. The airplane’s last observed track was at 1956:12. The calculated descent rate during the final portion of the turn was more than 17,000 ft per minute. The airplane’s fuselage came to rest about 0.1 nautical miles northwest of the last recorded position of the airplane. Figure 1: Plot of the final portion of the airplane’s flight path. A performance study was conducted by the NTSB’s Office of Research and Engineering and used available ADS-B data and ATC communications. The airplane had turned onto a northwesterly track toward BVX by 1831. The pilot requested FL 280 at 1833. The calculated calibrated airspeed was consistently above 150 kts. At 1841, the pilot reported to ATC that his satellite weather radar was not functioning and later asked for assistance navigating through weather. At 1908, he reported light chop over the previous 40 miles but that it was currently smooth. At 1944, ATC instructed the pilot to descend to FL 240 and to expect moderate chop. The airplane began to descend at a rate between 1,000 and 1,500 ft per minute. At 1947, the pilot checked in with a new ATC center on his route and reported descending with moderate chop. ATC responded by instructing the pilot to descend at his discretion to 17,000 ft. The airplane reached FL 240 (the previously instructed altitude) at 1949, where it stayed for less than a minute before continuing its descent. The first portion of this descent was at a rate of 2,000 ft/min before slowing to about 1,000 ft/min. The airplane continued to descend with a slight pause at 1952 at FL 220. At 1954, while descending through FL 200, ATC instructed the pilot to descend at his discretion to 6,000 ft. The rate of descent increased to near 3,000 ft/min, and the airspeed markedly increased from 170 kts to over 200 kts, exceeding the Flight Information Manual’s listed maximum operation limit of 187 kts calibrated airspeed. The airplane had been within 2° of the same northwesterly track for the previous 1 hour and 20 minutes. The steady track, altitude and climb rates were consistent with autopilot use. At 1955, the airplane passed through the ADS-B recorded selected altitude value of 18,016, after which the airplane began a brief climb and the ground track began to deviate to the right, no longer consistent with autopilot control. At 1955:20, the airplane began rapidly descending and after 1955:24 the airplane’s speed rapidly increased from 160 kts to 290 kts while in a tightening right turn. The airplane’s increasing speed in the descending tight turn exceeded the airplane’s structural limitations. About 1956, ATC attempted to contact the pilot with no response and issued an ALNOT at 2006. The wreckage was located about 2300 in a sparsely populated agricultural area. The fuselage came to rest on a 010° heading. The left wing was detached at the wing root and was found near the fuselage in two sections. The inboard portion of the left wing was found about 30 ft and 281° from the main wreckage, and the outboard portion of the left wing was found about 80 ft and 353° from the main wreckage. The inboard portion of the right wing was fractured at the wing root and found partially under the fuselage. The engine was attached to the engine mount and embedded in the ground. An odor consistent with jet fuel was present. Two small dogs were reportedly on board the airplane but were not located on scene or within the wreckage. The left horizontal stabilizer, vertical stabilizer, rudder, elevator, right aileron, right flap, and the outboard portion of the right wing were not located at the accident site. The elevator trim actuator rod was found with 0.5 inches of extension on the forward end of the rod, exposing 5 threads, consistent with a slight nose down trim position. The rudder trim actuator was not located in the vertical stabilizer and was not recovered for examination. A search for the missing components using a state police drone was conducted. No additional components were found during this effort. No additional components have been found as of the writing of this report. The main spar box structure was separated at the left and right wing roots. The spar box was pushed aft on the right side during the impact sequence. The spar box displayed upward U-shaped bending of about 12 inches along the outboard span of each side and was relatively unbent along the center span, consistent with positive loading. Black witness marks consistent with contact with the leading-edge wing de-ice boots were found on the right side of the aft fuselage, as seen in figure 2. Figure 2. Right side of the fuselage with black witness marks. The engine was found embedded in soft mud and remained attached to the engine mount. The exhaust duct exhibited torsional buckling consistent with torque production. All four propeller blades remained attached to the propeller hub. The blades exhibited bending progression from forward to aft in the direction of rotation consistent with thrust production. Additionally, rotational scoring and polishing were observed on each of the blades. Flight control continuity was established to the extent possible with the condition of the wreckage. All observed separations were consistent with impact or overload damage. No anomalies were found with the flight control system. The landing gear was found in the retracted position. The flap actuator displayed