The Transportation Safety Board of Canada (TSB) says the engine failure that led to a small plane crash near the Ottawa airport in the summer of 2025 was likely caused by improperly applied sealant in parts of the engine. The Grumman AA-5A aircraft with three people on board crash-landed just before 6 p.m. on July 31, 2025. The plane was on a forced approach to the airport at the time and crashed into a wooded area along Riverside Drive near Hunt Club Road. The pilot died in the crash; the two passengers were treated for non-life-threatening injuries. The TSB said the pilot reported trouble with the engine at 5:48 p.m., telling air traffic controllers at the Ottawa airport (YOW) that oil had leaked from the engine and splashed onto the windshield, obscuring the view. The airport gave the pilot clearance to land, but the plane did not make it to the runway. In a report released on Friday, the TSB found “several major failures and discrepancies” in the engine, including a bent rod, a fractured camshaft, and metallic debris in the oil filter. The most recent maintenance on the engine had taken place on July 7, 2025, just over three weeks prior to the crash. “The post-occurrence examination determined that the engine failure resulted from the failure of the No. 3 connecting rod, which subsequently fractured the camshaft. The No. 3 connecting rod failed in ductile overload, meaning it failed after significant permanent plastic deformation (e.g., stretching or bending) after the applied load exceeded its ultimate tensile strength,” the report states. In addition, the TSB said a sealant known as Loctite-515 was found in several areas of the engine outside the recommended instructions. The TSB said this misapplication likely caused the engine failure that ultimately led to the fatal crash. “The sealant would have reduced the nut thread clamping force, resulting in out-of-tolerance torque and insufficient clamping force between the crankcase mating surfaces during engine reassembly. This loss of clamping force likely caused unintended movement between the engine crankcase halves, abnormal operation of cylinder No. 3, and ultimately engine failure,” the TSB said. According to the TSB, Transport Canada issued a civil aviation safety alert on July 16, 2026, to inform owners, operators, and maintainers of Lycoming opposed cylinder engines of the potential of an engine failure due to improper application of sealant to crankcase parting surfaces during engine assembly. In a safety message, the TSB urged aircraft maintenance engineers to heed manufacturers’ recommendations when servicing planes. “Adherence to an aircraft manufacturer’s maintenance procedures and service instructions ensures continued airworthiness; deviations from them jeopardize safety. When faced with unclear or unfamiliar procedures, aircraft maintenance engineers are reminded to seek guidance directly from the manufacturer,” the TSB said.
