ERA25LA159

The airplane had recently undergone significant maintenance, including an engine overhaul, airframe reassembly, and an annual inspection. The accident flight was the third flight after the maintenance was completed. While flying at an altitude of 800 ft, the pilot reported a total loss of engine power. The pilot attempted to restart the engine but was unsuccessful. The pilot performed a forced landing in a grassy area, and during the landing, the airplane struck a rut in the grass and flipped over, resulting in substantial damage to the vertical stabilizer, the rudder, the horizontal stabilizer, and the left wing. Postaccident examination of the wreckage revealed that the spark plugs and internal portions of the cylinders were dark and soot-covered. This was consistent with an overly rich mixture during engine operation. Further examination of the airplane revealed that the exhaust system was severely corroded, with metal thinning at multiple locations and was porous in other locations. The portions of the exhaust system that were within the carburetor heat shroud displayed cracks that contained exhaust deposits, and there were exhaust deposits within the carburetor heat shroud. This is consistent with the cracks being present prior to the accident, and allowing exhaust gases to enter the carburetor heat system. Even if the carburetor heat was off at the time of the loss of power, some of the exhaust gases would still be able to enter the engine’s induction system, which would result in an enrichment of the fuel/air mixture. It is likely that during the test flight, sufficient exhaust gases entered the induction system, making the fuel/air mixture overly rich and resulting in the loss of engine power. The airplane’s most recent annual inspection had been completed less than a month prior to the accident, and the airplane had flown for only about 2.5 hours since then. It is unlikely that the observed corrosion occurred within that short period. While the mechanic reported that he didn’t believe that the exhaust was in that condition at the time of the annual inspection, the pilot confirmed that the exhaust had not been changed since the annual inspection. Given this information, it is likely that the mechanic failed to properly inspect the exhaust during the inspection and reassembly process. Had the mechanic performed a proper inspection, he would have found the exhaust in an unairworthy condition.

On March 27, 2025, about 1240 eastern daylight time, a Luscombe 8A, N28790, was substantially damaged when it was involved in an accident near New Port Richey, Florida. The private pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the owner/operator about one and a half months prior to the accident flight, the airplane had been reassembled and had a newly overhauled engine installed. The pilot reported that he had flown the airplane on two previous test flights without any mechanical anomalies. The purpose of the accident flight was to perform another test flight before using the airplane for the pilot’s flight review. After the pilot departed the Tampa North Aero Park (X39), Tampa, Florida, he flew northwest towards the west coast of Florida. Upon reaching an altitude of 800 ft over the water, the pilot reported that he experienced a total loss of engine power. The loss of power was smooth with no noticeable roughness, and the propeller continued to windmill. The pilot attempted to restart the engine using the primer and the throttle; however, the pilot was unable to restore engine power. The pilot searched for a suitable emergency landing area and decided to land in the grassy area of a water treatment plant. During the landing, the airplane hit a rut in the grass field and flipped over, resulting in substantial damage to the horizontal stabilizer, the vertical stabilizer, the rudder, and the left wing. A postaccident examination of the airplane revealed that the airplane’s center fuselage fuel tank remained installed and was undamaged. There were no signs of fuel leaks around the fuel tank or fuel lines. The fuel tank cap was separated from the fuel tank and was impact damaged at the vent tube. The vent was tested and operated normally when installed to the fuel tank. The fuel strainer bowl was removed, and the bowl and screen were visually inspected. Both the strainer housing and screen displayed signs of corrosion. There was a small amount of debris in the strainer screen, and portions of the screen were obstructed with buildup; however, the majority of the fuel screen was unobstructed. Low-pressure air was blown through the fuel system, and no obstructions were found. The engine remained attached to the airframe through its mounts, hoses, cables, and wires. The engine displayed impact damage to the exhaust system; the rest of the engine was undamaged. The crankshaft was rotated manually, and continuity was established between the crankshaft, camshaft, connecting rods, and associated components. There was no unusual binding or resistance during crankshaft rotation. During crankshaft rotation, all four cylinders displayed compression and suction. The cylinders were inspected using a lighted borescope; several of the internal cylinder components were dark in color, consistent with an overly rich mixture. Aside from the dark color, the internalcomponents displayed normal operating signatures. The magnetos remained attached to their respective installation points and were undamaged. During crankshaft rotation, both magnetos were capable of producing a spark for all four of their posts. The ignition harness remained attached to the magnetos and to each spark plug and the harness was undamaged. There were no signs of arcing or broken leads observed. The top spark plugs were removed, and the electrodes were visually inspected and the bottom spark plugs were inspected using a lighted borescope. The electrodes were heavily sooted and were dark in color, consistent with an overly rich mixture. All of the spark plugs displayed normal wear signatures. The carburetor remained attached to its installation point and was undamaged. The throttle control cable remained secure to the throttle control arm and was capable of normal movement. The carburetor fuel inlet line was secure, and there were no signs of fuel leaks. The carburetor inlet screen was removed and was found to be clear of any contamination. The carburetor was partially disassembled, and the internal components displayed normal operating conditions. The induction air filter remained installed in the bracket and had a significant amount of debris consistent with dirt and vegetation found at the accident site. There were no anomalies noted with the air filter. The rest of the induction system was intact and there were no signs of induction leaks or obstructions. Several of the rubber induction hose couplings were noted to be dry rotted; however, the couplings remained secured to the induction tubes. The exhaust system exhibited impact-damage signatures at several locations. The exhaust system also exhibited severe corrosion throughout. The exhaust risers were broken in several locations due to impact damage; however, the fractured areas were very thin, with very little material left, and the metal was brittle. Several other corroded areas were porous, with small holes within the metal. The exhaust shroud for carburetor heat was removed, and the portion of the exhaust that remained within the shroud was examined. Several cracks were not consistent with impact damage, and there were exhaust-leak signatures around them. The carburetor heat exhaust shroud also showed combustion deposits on its interior, consistent with exhaust gases entering the shroud. According to the airplane’s maintenance logbooks, the airplane was reassembled on March 1, 2025 at an aircraft total time of 1911.1 (about 2.5 hours prior to the accident). The engine overhaul entry was dated the same date as the reassembly completion for the airframe, and the overhaul was conducted by the same mechanic who had reassembled the airplane. The last annual inspection was performed on the same date as the airplane reassembly and engine overhaul and referenced inspecting the airframe and engine in accordance with Title 14 CFR 43 Appendix D. The regulations in Appendix D outlinedthe scope and detail of items that must be checked during the annual or a 100-hour inspection of reciprocating engine aircraft. According to 14 CFR Part 43, Appendix D, the exhaust stacks should be inspected for “cracks, defects, and improper attachment.” The airframe reassembly logbook entry, engine overhaul entry, and the annual entries did not mention repairing or replacing the exhaust system. According to the mechanic who performed the last annual inspection, the pilot had been the one to do most of the work to put the airplane back together, and the mechanic would inspect as needed. The mechanic also stated that during the annual inspection, he would have checked the exhaust system; however, he could not specifically remember checking the exhaust within the carburetor heat exchanger shroud. The mechanic was provided images of the exhaust system as it was found during the postaccident examination; the mechanic stated that he did not believe that the exhaust system was in that condition at the time of the annual inspection. The pilot was asked if the exhaust was the same exhaust at the time of the accident as it was during the annual inspection; the pilot stated that it was the same exhaust system. Despite the pilot initially stating that there were no anomalies during the previous two flights, the mechanic stated that the pilot had been experiencing engine issues after the annual inspection and had not requested the mechanic's assistance. The pilot, who also held a mechanic certificate with airframe and powerplant ratings, confirmed that he had been troubleshooting the engine himself; however, there were no logbook entries stating any work had been performed.