ERA23FA024

Structural icing on the tailplane that resulted in a tailplane stall and subsequent loss of control.

Shortly after departure to pick up a passenger at their destination airport about 75 nm away, the pilots climbed and turned onto a track of about 115° before leveling off about 11,000 ft mean sea level (msl), where the airplane remained for a majority of the flight. Pilot and controller communications during the flight were routine and there were no irregularities reported. As the airplane descended into the destination airport area, the airplane passed through areas of light to heavy icing where there was a 20 to 80% probability of encountering supercooled large droplets (SLD) during their initial descent and approach. While level at 4,000 ft msl, the flight remained in icing conditions, and then was cleared for the instrument approach to the runway. The flight emerged from the overcast layer as it crossed the final approach fix at 2,800 ft msl; the flight continued its descent and was cleared to land. The controller informed the flight that there was a vehicle on the runway but it would be cleared shortly, which was acknowledged; this was the final communication from the flight crew. Multiple eyewitnesses and security camera footage revealed that the airplane, while flying straight and level, suddenly began a steep, spinning, nearly vertical descent until it impacted a commercial business parking lot; the airplane subsequently collided with several unoccupied vehicles and caught fire. The airplane was certified for flight in known icing conditions and was equipped with pneumatic deice boots on each of the wings and tail surfaces. The pneumatic anti-icing system was consumed by the postimpact fire; the control switches were impact and thermally damaged and a reliable determination of their preimpact operation could not be made. Further examination of the airframe and engines revealed no indications of any preimpact mechanical anomalies that would have precluded normal engine operation or performance. During the approach it is likely that the airframe had been exposed to and had built-up ice on the control surfaces. It could not be determined if the pilots used the pneumatic anti-icing system, or if the system was inoperative, based on available evidence. Review of the weather conditions and the airplane’s calculated performance based on ADS-B data, given the speeds at which the airplane was flying, and the lack of any discernable deviations that might have been expected due to an extreme amount of ice accumulating on the airframe, it is also likely that the deice system, if operating at the time of the icing encounter, should have been able to sufficiently remove the ice from the surfaces. Although it is also uncertain when the pilots extended the landing gear and flaps, it is likely that the before-landing checklist would be conducted between the final approach fix and when the flight was on its 3-mile final approach to land. Given this information, the available evidence suggests that the sudden loss of control from a stable and established final approach was likely due to the accumulation of ice on the tailplane. It is likely that once the pilots changed the airplane’s configuration by extending the landing gear and flaps, the sudden aerodynamic shift resulted in the tailplane immediately entering an aerodynamic stall that maneuvered the airplane into an attitude from which there was no possibility to recover given the height above the ground. Postaccident toxicological testing detected the presence of delta-8 THC. Delta-8 THC has a potential to alter perception and cause impairment, but only the non-psychoactive metabolite carboxy-delta-8-THC was present in the pilot’s liver and lung tissue. Thus, it is unlikely that the pilot’s delta-8-THC use contributed to the accident.

The airplane was a high-performance, conventional-tail, pressurized, twin-engine turbo-propeller airplane and was designed and equipped for flight in instrument meteorological conditions, day or night, and into known or forecast icing conditions. The surface deice system would remove ice accumulation from the leading edges of the wings and stabilizers through the use of pneumatic boots. Ice would be removed by alternately inflating and deflating the deice boots. Pressure-regulated bleed air from the engines supplied pressure to inflate the boots. A venturi ejector, operated by bleed air, created a vacuum to deflate the boots and hold them down while not in use. To assure operation of the system in the event of failure of one engine, a check valve was incorporated in the bleed air line from each engine to prevent loss of pressure through the compressor of the inoperative engine. Inflation and deflation phases were controlled by a distributor valve. A three-position switch in the ICE PROTECTION group on the pilot's subpanel, placarded SURFACE DEICE - SINGLE - OFF MANUAL, controlled the deicing operation. The switch was spring-loaded to return to the OFF position from SINGLE or MANUAL. When the SINGLE position was selected, the distributor valve would inflate all of the airframe boots, both wings and tail. After an inflation period of approximately 7 seconds, an electronic timer switched the distributor to deflate the boots. After these boots have inflated and deflated, the cycle was complete. When the switch was held in the MANUAL position, all the boots would inflate simultaneously and remain inflated until the switch was released. The switch returned to the OFF position when released. After the cycle, the boots would remain in the vacuum hold-down condition until again actuated by the switch. According to the airplane’s Airplane Flight Manual (AFM) landing checklist: Figure 3 - Excerpt from AFM showing the landing checklist items. The Montgomery County Coroner’s Office performed the autopsy of the pilot. According to the autopsy report, the pilot’s cause of death was multiple injuries. The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem tissue of the pilot. Amlodipine and atorvastatin were detected in liver and muscle tissue. Carboxy-delta-8-THC was detected in liver at 96.9 ng/g and lung tissue at 17.7 ng/g. Amlodipine is a prescription medication commonly used to control high blood pressure. Atorvastatin is a prescription medication used to treat high cholesterol and reduce cardiovascular risk. Both medications are not generally considered impairing. Carboxy-delta-8-THC is a non-psychoactive metabolite of the psychoactive chemical delta-8-THC (which was not detected here). Delta-8-THC products are often marketed simply as “hemp” or “CBD” products, which consumers may not associate with psychoactive effects. Delta-8-THC is available in a variety of over-the-counter products for oral consumption, smoking, and inhalation. Delta-8-THC used in consumer products is typically chemically manufactured from cannabidiol (CBD), a chemical in the cannabis plant. Delta-8-THC has psychoactive and intoxicating effects that can impair motor coordination, reaction time, decision making, problem solving, and vigilance. The potency of delta-8-THC varies widely in consumer products. In one recent report, products were tested to assess how much delta-8- THC was contained within them; only 32% of tested products had accurate labeling for the amount of delta-8-THC contained. Delta-8 THC products have not been evaluated or approved by the Food and Drug Administration for safe use in any context. The Montgomery County Coroner’s Office performed the autopsy of the copilot. According to the autopsy report, the copilot’s cause of death was multiple injuries. The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem tissue from the copilot. No tested-for substances were detected. The airplane impacted an automobile dealership parking lot at an elevation of 614 ft msl about 3 miles northeast of the approach end of runway 21 at PKB. The airplane struck several vehicles before coming to rest on level pavement. The wreckage path was compact and oriented on a heading of 305° magnetic. All major components of the airplane were accounted for at the accident site. The cockpit and forward portions of the fuselage were crushed aft. A significant postimpact fire ensued consuming a majority of the fuselage and the cockpit area. The fuselage above the floorboards was totally consumed by fire. The instrument panel and all associated instrumentation, gauges, and switches were severely impact and thermally damaged. The left and right flaps, which were significantly damaged by impact and postimpact fire, remained attached to their respective mounts; the actuators indicated a flap position of 15°. Partial flight control continuity from the cockpit to the ailerons, elevator, and rudder was established through cables, bell cranks, and push/pull rods. All breaks in the cables consisted of a “broom straw” appearance indicative of overload and push/pull rod damage was consistent with overload and thermal damage. The pneumatic anti-icing system, including bleed lines, pneumatic boots, and their respective operating system on each of their respective wing leading edges and empennage, were consumed by postimpact fire; the switches were impact and thermally damaged. A reliable determination of their preimpact operation could not be made. Both engines were located in the wreckage in their respective attachment locations and both displayed significant impact and thermal damage. On-scene examination revealed that both engines displayed rotational contact signatures to their internal and external components, which is indicative of power generation at impact. There were no indications of any preimpact mechanical anomalies to any of the engine components that would have precluded normal engine operation. Both left and right propeller assemblies impact-separated from their respective engine propeller shaft flanges. All 4 blade shanks on each of the 2 assemblies remained attached to their respective hubs. There were no discrepancies noted in the components examined that would prevent or degrade normal operation before impact with terrain; all damage was consistent with high impact forces. Blade damage included chordwise/rotational scoring on both camber and face sides, bending forward/thrust direction, bending opposite rotation, and leading-edge gouging consistent with impact while rotating with power. There was no damage to indicate either propeller was feathered or at low pitch/idle power at the time of impact. Impact signatures indicated the blade angle for both propellers were approximately 30° while rotating with power and generating thrust. A Garmin GTN 750 was recovered from the wreckage and sent to the NTSB vehicle recorders laboratory for examination. The units exhibited severe impact and fire damage. The unit’s internal circuit boards were fire damaged and the extent of the damage precluded normal and advanced recovery procedures. No data pertinent to the accident were recovered. On October 18, 2022, at 0709 eastern daylight time, a Beech E-90, N515GK, was substantially damaged when it was involved in an accident in Marietta, Ohio. The two commercial pilots were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 positioning flight. The flight originated at the John Glenn Columbus International Airport (CMH), Columbus, Ohio, about 0640 and was enroute to Mid-Ohio Valley Regional Airport (PKB), Parkersburg, West Virginia. Automatic dependent surveillance - broadcast (ADS-B) data revealed that after takeoff from CMH the airplane climbed and turned on a ground track of 115°, and then leveled off at 11,000 ft mean sea level (msl), where it remained f