Accident Overview
On April 3, 2017, at about 1934 central daylight time, an amateur-built Aero Adventure Aventura UL amphibian airplane, registration N580TX, experienced a forced landing near Kitty Hawk Flying Field (TS67) in Garden Ridge, Texas. The airplane sustained substantial damage, and the pilot was seriously injured. The flight was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
Flight History
The pilot reported that the purpose of the local flight was to simulate water landings by flying low passes over a grass area adjacent to the western edge of runway 14/32 at TS67. The flight departed at approximately 1915 and completed several uneventful low passes before the accident. While on a right crosswind leg for runway 32, at about 300 feet above ground level, the engine began to sputter. Subsequently, the engine experienced a total loss of power and the propeller stopped rotating. The pilot established best glide airspeed and performed a forced landing in a nearby clearing among trees. The airplane landed hard on the hull with the main landing gear retracted.
Examination Findings
A Federal Aviation Administration (FAA) inspector examined the airplane at the accident site. The hull and both wings were substantially damaged during impact. Flight control continuity was confirmed from the cockpit inputs to the individual control surfaces. The landing gear were positioned for a water landing. The emergency ballistic parachute recovery system was armed but had not deployed. The three fuel tanks (one main and two auxiliary) contained automotive gasoline premixed with engine oil. The fuel system contained ample fuel, and the fuel shutoff valve was open. The fuel filter assembly and both carburetors contained fuel. Engine crankshaft continuity was confirmed by rotating the propeller. The spark plugs exhibited features consistent with normal engine operation. The propeller remained attached to the crankshaft and appeared undamaged; however, one of the three propeller blades had punctured the fabric-covered aft fuselage during impact.
Engine Test Run
The propeller was removed to facilitate an engine test run. The engine, a 55-horsepower Hirth model 3202 (serial number 901269), started and ran at various engine speeds without any hesitation or anomalies. The postaccident examination and successful engine test run revealed no evidence of a mechanical malfunction or failure that would have precluded normal operation.
Carburetor Icing Considerations
According to a carburetor icing probability chart contained in FAA Special Airworthiness Information Bulletin CE-09-35, entitled "Carburetor Icing Prevention", the recorded temperature and dew point were in the range of susceptibility for the formation of carburetor icing. The bulletin notes that if ice forms in the carburetor of a fixed-pitch propeller aircraft, the restriction to induction airflow will result in roughness in engine operation and a drop in engine speed. The airplane was not equipped with a carburetor heat system; however, the engine was equipped with two Dell'Orto sliding carburetors. According to the textbook "Aircraft Powerplants, Fifth Edition" by Bent/McKinley, carburetors that incorporate a variable-venturi design (e.g., sliding carburetors) are not generally prone to carburetor icing.