History of Flight
On April 2, 2024, at 1038 eastern daylight time, an experimental amateur-built Merlin Lite motorglider, registration N622PC, was substantially damaged when it crashed near Mulberry, Florida. The private pilot was fatally injured. The motorglider was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
The manager of the company from which the pilot/builder had purchased the kit reported that the pilot flew the motorglider two days before the accident, and to his knowledge that was the only flight the pilot completed in that motorglider. The manager spoke with the pilot after that flight, and the pilot mentioned practicing “crow hops.” According to an article in the September 2022 issue of EAA Sport Aviation magazine, a crow hop involves lifting the airplane off the runway, cruising a few feet forward, and then landing.
A witness observed the motorglider taxi toward the end of runway 14 at South Lakeland Airport (X49), Lakeland, Florida, noting that the engine sounded “a bit rough but it is only a small 2-stroke so I didn’t think it was unusual.” When the witness heard the motorglider at a high power setting, he and another witness turned to watch the takeoff. Multiple witnesses reported that when the motorglider reached about 100 to 150 ft above ground level, the engine went silent. Review of surveillance video revealed that after liftoff, as the motorglider was about midfield, it turned right, then left, then pitched up before the left wing dropped and the motorglider began a near-vertical left rotating descent until it impacted the ground.
Personnel Information
The pilot’s logbooks showed he received his first instructional flight in a glider on September 17, 1972. From that first flight to the accident date, the pilot accumulated 118.6 hours of flight time over 283 flights. He was issued a private pilot certificate with a glider rating on April 26, 2018, and was endorsed for self-launch operations on February 15, 2024.
A former flight instructor reported that he and the pilot performed five flights from April 26, 2021, to May 17, 2021, in a Pipistrel Alpha motorglider. The pilot came to the flight school for training while building his own motorglider. The instructor stated that a long commute and unfavorable weather caused the pilot to pause training, adding that “considerable practice was still required before considering solo flights.”
The last flight instructor to fly with the accident pilot was the one who gave the endorsement for self-launch. That instructor reported the pilot’s “aeronautical knowledge, demeanor, and skills were exemplary; he was a model student and a pleasure to fly with. He arrived highly proficient, well-trained, and needed very minimal additional training from me.” During training, they performed an aborted takeoff maneuver where the instructor reduced power to idle at about 100 ft agl to simulate an engine failure on takeoff, and the pilot was expected to land on the remaining runway. The instructor noted that he had to prompt the pilot “to aggressively lower the nose with loss of engine power to keep airspeed.”
Aircraft Information
FAA airworthiness records showed the motorglider received an experimental amateur-built airworthiness certificate on October 31, 2023. This was only the second motorglider built from the kit provided by Aeromarine LSA, and it was equipped with a two-stroke Polini Thor 303DS single-cylinder engine.
The kit manufacturer manager, who flew the motorglider three days before the accident, reported that the normal takeoff roll was between 200 ft and 250 ft and the landing roll was about 200 ft or less.
Wreckage and Impact Information
The motorglider came to rest about 1,500 ft from the threshold of runway 14. The distance from the accident site to the end of the available grass area was about 1,300 ft.
The fuselage displayed crushing and buckling in multiple locations. The empennage was partially separated but remained attached to the fuselage by control cables, control rods, and the bottom skin. The vertical stabilizer, rudder, horizontal stabilizer, elevator, and elevator trim tab remained attached and undamaged. The electric trim was visually in a neutral position. The right wing remained attached; its leading edge was impact crushed aft along its full length. The right aileron and right flap (in the up position) remained attached and exhibited impact damage. The left wing remained attached but was impact fractured outboard of the flap, remaining attached through the left aileron control rod. The outboard two thirds of the left wing’s leading edge showed impact crushing aft. The left aileron and left flap (in the up position) remained attached. Continuity was confirmed from all flight control surfaces to the cockpit controls.
The engine had broken free from the airframe and displayed impact damage. The propeller flange was impact separated from the propeller driveshaft. The cylinder head and cylinder sleeve were removed from the engine. A quarter-sized hole was found in the middle of the piston, with eroded material around the hole. The cylinder sleeve had minor scoring, and the cylinder head was undamaged. Intake and exhaust ports were unobstructed with normal operating signatures.
The piston head, cylinder sleeve, and cylinder head were examined at the National Transportation Safety Board Materials Laboratory. The examination found a hole in the middle of the piston crown, with light gray deposits covering portions of the crown surface. The remaining piston crown and interior cylinder head surfaces appeared free of heavy combustion deposits. Machining marks and partial vibro-peen markings were visible on the piston crown.
The piston crown had features consistent with pre-ignition damage. Pre-ignition can occur due to an overheated spark plug tip, glowing hot carbon or lead deposits, a burned exhaust valve, use of unsuitable fuel with too low an octane rating or contamination with diesel, excessive leaning causing higher combustion temperatures, or inadequate ventilation or general engine overheating.
The original factory airbox had been removed and replaced with a single cone-type filter. When asked if this was an approved modification, a representative of the engine manufacturer replied, “We have never approved such modification because it drastically modifies the carburetion and the stability of the engine.”
The kit manufacturer manager reported that they had changed the carburetor jet after consulting a Polini engine dealer. The dealer reported he worked with the pilot who was having an issue with the engine running too rich. He recommended changing the main jet from the factory jet to a 118, which would lean the mixture slightly and should correct the rich mixture issue. The dealer noted that it was typical to burn a hole in the piston if the mixture was too lean and mentioned that a different customer who ran an engine too lean burned a hole in his piston “in about 30 seconds.”
Medical and Pathological Information
According to the autopsy report from the Office of the District Medical Examiner 10th Judicial Circuit of Florida, the pilot’s cause of death was blunt force trauma, and the manner was accident.
The FAA Forensic Sciences Laboratory performed toxicological testing of postmortem specimens from the pilot. Sacubitril and desethyl sacubitril were found in aortic blood and urine. Sacubitril is a prescription medication available as a combination drug with valsartan, which was also detected. This combination is used for chronic heart failure. Desethyl sacubitril is a metabolite. Sacubitril is not typically impairing.
Toxicological testing also found Tamsulosin, Loratadine, Desloratadine, and Carvedilol. Tamsulosin (Flomax) is for benign prostate hyperplasia and is acceptable for pilots. Loratadine (Claritin) and its metabolite Desloratadine are non-prescription non-sedating antihistamines for allergies, acceptable for pilots. Carvedilol (Coreg) is a beta-blocker for high blood pressure, acceptable for pilots.
Survival Aspects
The motorglider was equipped with a 4-point harness. Both lap belt attachments remained attached to the fuselage. The shoulder harness attachment point was partially torn from the airframe attachment point. The seatbelts had been cut by first responders to facilitate pilot recovery. The seat belt buckle remained buckled and operated normally. The pilot was wearing a helmet typically used in helicopter operations.