ERA23LA331

While enroute to the destination airport the pilot described that the engine “shuddered” before smoke began emanating from the engine area and entered the cockpit. The pilot then attempted to land at a diversionary airport and during the diversion described that the engine intermittently lost power and he observed sparks and flames emanating from it. Upon reaching the midpoint of the diversionary runway, the airplane was flying at too fast of an airspeed to land, so the pilot performed a go-around, during which the engine lost power and the propeller stopped rotating completely. The airplane subsequently struck trees and was substantially damaged. Postaccident examination of the wreckage revealed that the engine’s crankcase was breached in the vicinity of the No. 3 cylinder. A deformed connecting rod was recovered, but the connecting rod's end cap was not. The crankshaft journal exhibited heavy mechanical damage. An unquantified amount of oil residue was found in the engine cowling and on the airframe. The wreckage was subsequently sold for salvage and a further detailed examination of the engine could not be completed. Based on this information, the loss of engine power was likely the result of the separation of the No. 3 connecting rod from the crankshaft.

On August 10, 2023, about 2230 eastern daylight time, a Cessna C175, N7117M, was substantially damaged when it was involved in an accident near Wetumpka, Alabama. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during a flight to Shelby County Airport (EET), Alabaster, Alabama, the airplane operated without issues until it suddenly shuddered and smoke began emanating from the engine compartment and into the cockpit. The pilot recalled passing a private airfield and elected to divert and land there. While enroute to the private field, the propeller intermittently stopped and restarted rotating. Upon locating the paved runway, the pilot initiated a series of 360° turns to lose altitude and reduce airspeed. During the second 360° turn, the pilot noticed what appeared to be flames and sparks emitting from the engine area. After completing the final 360° turn, the airplane's airspeed increased to approximately “130 mph and only slowed to 110 mph near the midpoint of the runway.” Concerned about potential injuries from colliding with trees at the runway's end, the pilot decided to go around and land in the opposite direction. The pilot applied full throttle and a full-rich mixture, maneuvering to the right of the field to avoid houses and then initiated a left turn back toward the runway. Midway through the turn, the propeller stopped rotating and the airplane began losing altitude. The pilot leveled the wings and pulled back on the yoke to a near-stall attitude, dragging the tail through the trees to reduce speed. The airplane slowed, and the fuselage came to rest atop the trees before descending through the branches and coming to rest on the ground. A Federal Aviation Administration inspector who responded to the accident site reported that both wings and the fuselage were substantially damaged. The leading edge of the right wing sustained impact damage. The right-wing fuel tank was breached, and no fuel remained in the tank. The left-wing fuel tank was undamaged and contained an unquantified amount of fuel. No contamination or obstructions were found in the fuel system. Examination of the engine revealed a breach in the engine crankcase around the No. 3 cylinder. A deformed connecting rod that was recovered near the nose landing gear after the airplane was removed from trees. The connecting rod's end cap was not recovered. The crankshaft journal exhibited heavy mechanical damage. An unquantified amount of oil residue was found in the engine cowling and on the airframe. The wreckage was subsequently sold as salvage without prior coordination of the FAA or the NTSB and not available for further detailed examination. A review of the airplane’s maintenance logbooks revealed an entry documenting the removal and repair of the No. 5 and No. 6 cylinders that was completed on July 12, 2022. Review of the maintenance invoice correlated with that log entrydocumented work on cylinders No. 1 and No. 2. In a telephone conversation with the pilot/owner, he stated that to his knowledge, the airplane’s previous owner had recently replaced "the back two cylinders," and he believed that the damage/failures observed on the engine as a result of the accident flight was related to one those cylinders. He was unable to reconcile the discrepancies between the maintenance logbooks and the repair invoices. The repair facility who performed the maintenance work also was unable to provide any additional information regarding the discrepancies.