Kingsport, TN, USA
N67WR
CALVIN NATE H VELOCITY STD RG E
The private pilot reported that, during a low power visual approach to land, the experimental, amateur-built airplane became low and slow on final approach. When he increased power to arrest the descent, the engine did not respond, and the airplane continued to descend, stalled, and impacted the approach lighting system and terrain before coming to rest about 400 ft short of the runway threshold. The fuselage, canard, and both wings sustained substantial damage. Postaccident examination of the airplane did not reveal any evidence of a preimpact mechanical malfunction or failure that would have precluded normal operation. Weather conditions at the time were conducive to the formation of serious carburetor icing at glide power. The carburetor heat lever was found in the off position, and the pilot reported that he did not use carburetor heat for the approach to landing; thus, carburetor ice likely formed and reduced the power available to stop the descent into the approach lights and terrain.
On September 19, 2018, at 2010 eastern daylight time, an experimental amateur-built Velocity STD RG E, N67WR, was substantially damaged when it impacted an approach lighting system and terrain while landing at the Tri-Cities Airport (TRI), Kingsport, Tennessee. The private pilot and passenger were seriously injured. The airplane was privately owned and operated as a personal flight under the provisions of Title 14 Code of Federal Regulations Part 91. Night visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight, which originated from Columbus Airport (CSG), Columbus, Georgia, at 1817. According to the pilot, the enroute portion of the cross-country flight was uneventful. He reported that when he was cleared for a visual approach to runway 23, the airplane was higher than usual. Subsequently, he reduced power nearly to idle, and applied the speed brake to increase the descent rate. Once on final approach, the pilot noticed that the airplane "began to be slow and was low," and while over the approach lights, he increased the throttle, but the engine "did not respond at all." The airplane continued sinking and began to stall. Shortly thereafter, the airplane impacted approach lights and terrain. A witness located on the airport's ramp reported that he "heard a high revving engine noise and turned towards the approach end of the runway and saw [a] small plane strike the [approach] lights." According to a Federal Aviation Administration (FAA) inspector who examined the airplane at the accident site, damage to the approach lighting system began with the elevated approach lights about 900 ft from runway 23 and continued to where the airplane came to rest about 400 ft short of the runway threshold. All major flight control surfaces were located along the debris path. All three propeller blades fragmented at the propeller hub. The mixture and propeller control levers were found full forward and the throttle was found 3/4 of the way forward. The carburetor heat lever was found in the off position. The fuselage, canard, and both wings sustained substantial damage. Examination of the engine revealed crankshaft continuity when rotating the propeller flange by hand. All cylinders remained attached to the engine and thumb compression was attained on all cylinders when rotated by hand. All spark plugs were examined, and no anomalies were noted. The oil screen was free of debris. The carburetor was examined, and no anomalies were noted. The throttle, mixture, and propeller control cables remained attached to their respective attach points, and each moved freely. There was no damage observed to the induction system. According to the FAA Air Traffic Control Tower Manager at TRI, the approach lighting system and precision approach path indicator (PAPI) were on at the time of the accident. A functional test of the PAPI was conducted the following morning after the accident, and no malfunctions were noted. According to FAA airman records, the pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. He was issued a third-class medical certificate in October 2017. He reported a total of 451 flight hours, 61 hours of which were in the accident airplane make and model. According to FAA airworthiness records, the canard design airplane was powered by a Franklin 6A-350-C1R, 205-horsepower engine. It was equipped with retractable landing gear in the tricycle configuration and had 4-seats. The most recent annual inspection was completed in July 2018. The weather conditions reported at 1953 at TRI, included calm wind, few clouds at 4,500 ft, visibility 10 miles, temperature 24°C, and dew point 20°C. Review of a Carburetor Icing Probability Chart for the given temperature and dew point revealed that the conditions were conducive to serious icing at glide power. The pilot reported that he did not use carburetor heat during the low power descent because "it was not cold." He reported that he did not use carburetor heat in this airplane but was taught to use carburetor heat in a different airplane he had flown in the past as a student pilot. According to the FAA Pilot's Handbook of Aeronautical Knowledge, carburetor ice occurs due to the effect of fuel vaporization and the decrease in air pressure in the venturi, which causes a sharp temperature drop in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve. The reduced air pressure, as well as the vaporization of fuel, contributes to the temperature decrease in the carburetor. Ice generally forms in the vicinity of the throttle valve and in the venturi throat. This restricts the flow of the fuel-air mixture and reduces power. If enough ice builds up, the engine may cease to operate. Carburetor ice is most likely to occur when temperatures are below 70°F (21°C) and the relative humidity is above 80 percent. Due to the sudden cooling that takes place in the carburetor, icing can occur even in outside air temperatures as high as 100°F (38 °C) and humidity as low as 50 percent.
The pilot's failure to use carburetor heat in conditions conducive to serious carburetor icing at glide power, which resulted in a partial loss of power and an aerodynamic stall.
Source: NTSB Aviation Accident Database
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