History of Flight
On August 24, 2018, at approximately 1535 eastern daylight time, an Aeronca 7AC Champion, registration N65HM, was substantially damaged when it impacted terrain shortly after takeoff from Cranland Airport (28M) in Hanson, Massachusetts. The commercial pilot was fatally injured and the passenger was seriously injured. The airplane was privately owned and operated as a personal flight under 14 CFR Part 91. Visual meteorological conditions prevailed; no flight plan was filed.
Airport security video showed the airplane at about 100 feet above ground level as it passed the departure end of the runway. The airplane was not climbing and began banking left; the left turn continued as it descended behind trees and struck terrain. The video also indicated the airplane operated at idle engine power on the ground for about 7 minutes before beginning the takeoff roll.
First responders reported the airplane came to rest in a nose-down, near-vertical position and had to be moved for rescue operations. The passenger told a first responder that the airplane "stalled."
Pilot Information
According to FAA records, the pilot held a commercial pilot certificate with ratings for rotorcraft-helicopter, instrument helicopter, and private pilot privileges for airplane single-engine land and sea. He was issued a first-class medical certificate on October 10, 2017, with no limitations. His logbook showed 195.7 hours of civilian flight experience, of which 4 hours were in the accident airplane in the previous 3 years.
Aircraft Information
The airplane was manufactured in 1946 and equipped with a Continental Motors Inc. C90 series, 90-horsepower engine driving a fixed-pitch propeller. An annual inspection was completed on October 1, 2017, at a total time of 1,521.4 hours and tachometer time of 3,215.1 hours. After the accident, the tachometer indicated 3,325.1 hours.
The airplane was flown the day before by the owner's son and the accident pilot. The son reported no anomalies during their hour-long flight. He stated he usually applied carburetor heat during ground idle due to "carburetor icing possibilities."
The engine operating instructions stated that during pretakeoff ground test, the carburetor heat control should be moved to the full HOT position and a decrease in engine speed observed, then returned to full COLD. The instructions noted that under some conditions, ice may form in the carburetor during ground test and must be eliminated before takeoff.
Meteorological Information
The 1552 weather observation at Plymouth Municipal Airport (PYM), about 8 miles southeast, included wind 210° at 9 knots, 10 miles visibility, clear skies, temperature 27°C, dew point 12°C, and altimeter 30.20 inches of mercury. The FAA Special Airworthiness Information Bulletin (SAIB) CE-09-35 carburetor icing probability chart showed a probability of serious icing at glide power for the reported temperature and dew point.
Wreckage and Impact Information
The airplane impacted a bog 470 feet east of the departure end of runway 18 at an elevation of 59 feet msl. All components were nearby. The nose section was impact crushed aft. Flight control continuity was confirmed from cockpit to surfaces. The carburetor heat control was in the OFF position. Leading edges of both wings were impact crushed along their spans. Fuel samples tested negative for water. The empennage remained intact. No stall warning system or angle of attack indicator was installed.
The engine remained attached; one propeller blade was bent slightly aft, the other straight. Crankshaft continuity was confirmed. Cylinders had thumb compression and suction. Valvetrain continuity was confirmed. The carburetor hot air inlet was impact crushed. Carburetor heat control continuity was confirmed but the control could not be moved due to impact damage. The carburetor was disassembled; no anomalies were found in the gasket, float assembly, butterfly valve, or fuel pump. The bowl contained brownish fluid similar to bog water with a smell of 100LL fuel.
Left and right magnetos produced spark when rotated. Top spark plugs were in normal condition except the No. 2 top spark plug, which was "normal-worn out."
Additional Information
FAA SAIB CE-09-35 states that carburetor icing can occur above freezing due to fuel vaporization and the Venturi effect, causing sudden cooling. A drop in rpm (fixed-pitch propeller) indicates ice, often with engine roughness.
Medical and Pathological Information
The Office of the Medical Examiner performed an autopsy; the cause of death was multiple blunt force injuries. Toxicology tested negative for ethanol. Ketamine, norketamine, midazolam, lorazepam, morphine, and fentanyl were detected, consistent with emergency medical treatment.
Tests and Research
An exemplar airplane with a Continental C90 engine was started and the fuel selector turned OFF; the engine ran for 31 seconds before losing total power without sputtering. When restarted and idled for about 5 minutes, then shut down, condensation was noted on the carburetor and intake. Ambient temperature was 28°C, dew point 15°C—showing probability of serious icing at glide power on the icing probability chart.