WPR22LA138

During a local flight, the pilot was maneuvering the amateur-built experimental airplane to final approach in the traffic pattern when the engine lost total power. The pilot noticed that the propeller was not windmilling and attempted to restart the engine but was unsuccessful. Subsequently, the airplane impacted trees about 1,000 ft short of the runway threshold and sustained substantial damage to both wings. Postaccident examination of the engine revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. However, examination of the fuel system revealed a clogged fuel filter on the left fuel line and a partially clogged fuel filter on the right fuel line. The pilot stated that he had the left fuel tank selected at the time of the accident. Laboratory spectrum analysis determined the material clogging the fuel filters was consistent with an epoxide used in resins and sealants. Although the spectrum of the clogging material did not match that of an uncured sample of the sealant used during manufacture of the airplane, this was likely due to the cured state of the clogging material. The epoxide likely deteriorated, with the fragments becoming loose and clogging the fuel filters.

On March 30, 2022, about 1330 mountain standard time, an experimental amateur-built Cozy Mark IV, airplane, N294MV, was substantially damaged when it was involved in an accident near Tucson, Arizona. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during the base turn to final, while descending at idle power, he noticed that the alternator indicator light was flashing and that there were no indications of engine rpm or manifold pressure. He further reported that there was no roughness or abnormal noise associated with the loss of power. The pilot immediately switched fuel tanks, confirmed that the boost pump was on, and noticed that the propeller was not windmilling. He attempted to restart the engine but was unsuccessful. Subsequently, the airplane impacted trees about 1,000 ft short of the runway threshold and sustained substantial damage to both wings. Postaccident examination of the engine revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. However, examination of the fuel system revealed a clogged fuel filter on the left fuel line from the left fuel tank to the engine. The fuel filter on the right fuel line also had contamination but was only partially clogged. The pilot stated that he had the left fuel tank selected at the time of the accident and normally selects it while flying in the traffic pattern. A sample of the material that clogged the fuel filter was sent to the National Transportation Safety Board Materials Laboratory for analysis along with samples of two types of foams and uncured sealant material used in building the airplane for comparison. Spectrum analysis of the clogging material determined that its spectrum was consistent with an epoxide. A spectral library search found matches to several epoxy resins and sealants. The material sample did not match any of the samples submitted for comparison including the uncured sealant sample. However, the clogging material was noted to have cured based on its appearance and the similarities to the spectral matches found in the library search.