WPR15FA181 · Beech F35

The pilot receiving instruction reported that following a normal taxi and pre takeoff engine run up, the flight instructor initiated the takeoff sequence for a local instructional flight. He noted that during the takeoff, the flight instructor retracted the landing gear and the airplane began a slow climb, however, it seemed like the airplane had no power to climb. The pilot receiving instruction further stated he saw the flight instructor managing the fuel and verifying the throttle position as the airplane began to descend. Subsequently, the airplane impacted a grassy wetland area on the departure end of the runway.

Postaccident examination of the airplane revealed erratic fuel flow from the fuel nozzles. Further examination of the engine revealed that the fuel servo inlet fuel screen was installed 180-degrees opposite of the manufacturer's installation instructions, which would allow for unfiltered debris to flow throughout the fuel system. The engine was installed on a test cell and during the first 5 engine run attempts, it was noted that the engine was not firing on all cylinders, and would not produce rpm over 1,500. The fuel servo unit was removed and a carburetor was subsequently installed. The engine started and ran successfully at various power settings for about 23 minutes prior to being shut off utilizing the engine test cell fuel shut off. Disassembly of the fuel servo revealed a significant amount of debris in two of the fuel diaphragm housings, and on the diaphragm assemblies, one of which regulates fuel to the fuel injectors. The mixture control valve and idle valve exhibited evidence of corrosion. The idle valve was found seized within its respective galley. Upon removal, corrosion was observed within the galley.

The debris observed within the fuel servo was removed and visually, the debris was composed of two optically different particle types. The debris was predominately larger grey white particles mixed with lesser amounts of smaller dark brown particles. X-ray fluorescence spectrometer examination of several different areas of the grey white particles indicated compositions consistent with aluminum alloys. The white appearance and crumbling nature of the particles was indicative of heavily oxidized aluminum. Spectra of the dark brown particles were consistent with low alloy steels. The appearance and dark color was indicative of heavy oxidization of the particles. The source of the debris within the fuel servo and whether the misinstalled fuel screen allowed the debris to enter the servo could not be determined. It is likely that the debris within the fuel servo was distributed throughout the engine fuel system, which allowed for restricted fuel flow to each of the fuel injectors, which would result in an erratic running engine and partial loss of engine power.

Verbatim NTSB analysis and probable cause from the NTSB dataset