ERA24LA276

The pilot reported that shortly after reaching his initial cruise altitude, he heard a “loud bang” and the pusher-style engine lost all power. The pilot unsuccessfully attempted to restore engine power multiple times. After he determined that he would be unable to restore power to the engine, the pilot performed a forced landing in a wooded area, resulting in substantial damage to the airplane. Postaccident examination of the airplane at the accident site revealed that the exhaust muffler and tailpipe assembly was separated from the engine and not located at the accident site. Following recovery, a postaccident examination of the airframe and engine revealed the only anomaly to be the missing exhaust muffler and tailpipe assembly. Two of the propeller blades, which were mounted aft of the engine, displayed impact damage signatures and portions of the blades had broken free, which were also not located. Only one of the eight exhaust springs that attach the exhaust muffler and tailpipe assembly to the exhaust risers remained with the exhaust risers. The spring displayed deformation on the exhaust muffler end consistent with being pulled out of position. It is likely that the exhaust muffler and tailpipe assembly had separated from the exhaust risers during flight and impacted the propeller, which resulted in a loss of power of the engine. The reason for the exhaust muffler and tailpipe separation could not be determined.

On June 25, 2024, at 12:55 eastern daylight time, an experimental, amateur-built SeaRey, N453TS, was substantially damaged when it was involved in an accident near New Ipswich, New Hampshire. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot intended to fly from the Brookline Airport (NH16), Brookline, New Hampshire, to the Plateau Sky Ranch Airport (1F2), Edinburg, New York. The pilot reported that the preflight inspection, engine run-up, and takeoff were all normal. About 20 minutes after takeoff, when the airplane reached the initial cruise altitude, the pilot heard a “loud bang” and the pusher-style engine stopped producing power. The pilot attempted to restore power four times; however, the engine never regained power. The pilot performed a forced landing in a wooded area, resulting in substantial damage to the airplane’s fuselage, horizontal stabilizer, and both wings. An FAA inspector examined the wreckage at the accident site and accounted for all major airplane components except for the engine’s exhaust muffler and tailpipe assembly. A search around the accident site for the exhaust muffler and tailpipe assembly was unsuccessful. Postaccident examination of the airframe revealed that the fuel tank contained about 11 gallons of fuel that had an odor and color consistent with automotive fuel. The airframe fuel strainer bowl remained secure and was full of fuel. There were no signs of debris or water contamination within the fuel system. The engine throttle and choke control cables were secured in the cockpit and at their respective control arms at the engine. The airframe electrical fuel pump was secured to the fuel lines, and the electrical power wires were secure. The electric fuel pump operated normally when connected to a 12-volt battery. There were no signs of fuel leaks or blockages with the airframe fuel system components. The engine remained attached to the airframe and was undamaged. Continuity was established between the propeller shaft, gearbox, crankshaft, camshaft, connecting rods, and associated components by rotating the propeller shaft manually. All four cylinders displayed good thumb compression and suction, and all the rocker arms and valves operated normally during propeller shaft rotation. The cylinders were inspected with a lighted borescope; the piston faces, cylinder walls, and valve heads displayed normal operating and combustion signatures. The electronic ignition system remained secure to the engine and to the wiring harness. All the ignition leads were secured to the electronic ignition system and to each spark plug and were undamaged. The spark plugs were removed and all of the electrodes displayed normal operating and wear signatures. The engine-driven fuel pump remained secure to the engine and to the fuel lines and was capable of pumping residual fuel during propeller shaft rotation. Both carburetors had detached fromtheir respective induction hoses and were undamaged. The carburetors were disassembled and the internal components displayed normal operating signatures. All 4 exhaust risers remained attached to their respective cylinders; however, the Nos. 1, 3, and 4 exhaust risers were found to be loose at the attach point to the cylinder. The exhaust muffler and tailpipe had separated from the exhaust risers and was not with the wreckage. Only one of the eight exhaust springs remained attached to the exhaust risers. The spring remained attached to some safety wire of the No. 2 exhaust riser; the spring displayed deformation the end of the spring that would have attached to the exhaust muffler assembly. The rest of the exhaust risers contained varying amounts of safety wire attached to the exhaust spring brackets. Several of the exhaust spring brackets were noted to have deep gouges/grooves in the bracket that were consistent with excessive wear. The Nos. 1, 2, and 3 exhaust risers displayed deformation around the end that would be inserted into the muffler and tailpipe assembly; the No. 4 exhaust riser end was undamaged. Postaccident examination of the propeller, which was mounted aft of the engine, revealed that the propeller remained attached to the propeller shaft and the blades displayed impact damage signatures. One propeller blade was broken approximately in half, another blade was missing the blade tip and a large section of the cambered side of the blade, and the third blade displayed only minor impact damage signatures. According to the recovery personnel, the separated portions of the propeller blades were not located at the accident site. The last maintenance on the engine was performed on May 20, 2024, about a month before the accident, and was an owner-performed oil and filter change. The last condition inspection was performed on August 1, 2023, almost 11 months before the accident.