CEN20LA005

The pilot reported that the airplane was fully loaded with fuel and that all preflight checks were normal for the personal flight. He indicated that, after departure, as the airplane reached between about 10 and 15 ft above ground level, the engine power rolled back "opposite of a surge." He landed straight ahead into brush past the runway end. During the landing, the right main landing gear and nose landing gear collapsed, and the fuselage sustained substantial damage. During the engine examination, several items were identified that could have contributed to a reduction or loss of engine power, including a lack of a fuel return line, a loose exhaust pipe, dirty air filters, and a disconnected choke lever. However, an engine test run was conducted without correcting any of the identified deficiencies, and the engine performed without interruption; no anomalies were noted. Further, no anomalies were noted during the airframe examination. Although the conditions were conducive to serious carburetor icing at glide power, the airplane was operating at takeoff power at the time of the accident. The reason for the loss of engine power could not be determined.

***This report was modified on April 17, 2020. Please see the docket for this accident to view the original report.*** On October 5, 2019, about 1030 central daylight time, a Zenair Zenith CH-701 airplane, N701BJ, impacted terrain near Garden Ridge, Texas, following a partial loss of engine power after takeoff. The private pilot and passenger were not injured. The airplane was substantially damaged. The airplane was registered to the pilot and operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and the flight which was operating without a flight plan. The flight was originating from Kitty Hawk Flying Field Ultralight Flightpark (TS67), Garden Ridge, Texas, when the accident occurred. The pilot reported the airplane was fully loaded with fuel, it started normally, and all preflight checks were normal. The airplane reached 10-15 ft above the ground during takeoff when the engine RPM rolled back "opposite of a surge." The pilot pulled the throttle control back to idle and landed straight ahead in an area of brush off the end of the runway. The right main gear and nose gear collapsed, and the fuselage exhibited buckling. An examination of the engine and airframe was conducted by a representative of Rotech and a Federal Aviation Administration inspector. No anomalies were found during the airframe examination. When first examined, the engine was attached to the engine mount and firewall of the airplane, and the engine cowling was still in place. The retaining nut for the 2/4 cylinder carburetor choke lever was not present and the choke lever was found detached at the control valve. The fuel feed line to the mechanical fuel pump was badly cracked. The carburetor float bowls were removed and inspected. Some debris was found in the 2/4 carburetor; however, the main jet was clear of any obstructions. Examination also found there was no fuel return line installed in the airplane as recommended by the engine manufacturer, the No. 3 cylinder exhaust pipe was loose, and the air filters were dirty. The damaged propeller was removed from the engine and a new propeller was installed for test run purposes. No other repairs were made to the engine. The engine was turned over with the use of the engine's electric starter. After a few rotations the engine started and ran at idle. The throttle was then advanced to around 3,500 rpm and then to 4,000 RPM. All engine parameters appeared normal after several minutes and the engine was shut down. No anomalies were noted during the engine test run. The pilot reported at the time of the accident the temperature was 80° F and the dewpoint was 72° F. A review of the Federal Aviation Administration's carburetor icing probability chart indicated that weather conditions at the time of the accident were conducive to serious carburetor icing at glide power.