Engine failure that led to fatal small plane crash in Ottawa linked to misapplied sealant: TSB

The Transportation Safety Board of Canada (TSB) reports that an engine failure linked to a small-plane crash near Ottawa in summer 2025 was likely caused by improperly applied sealant in engine areas.

The aircraft involved was a Grumman AA-5A carrying three people. It crash-landed on July 31, 2025, during a forced approach to Ottawa airport and came down in a wooded area along Riverside Drive near Hunt Club Road.

The pilot notified air traffic controllers at Ottawa (YOW) at 5:48 p.m. that oil had leaked from the engine and splashed onto the windshield. Despite clearance to land, the plane did not reach the runway.

The TSB’s post-accident examination found major engine failures and discrepancies, including a bent rod, a fractured camshaft, and metallic debris in the oil filter. The most recent engine maintenance occurred about three weeks before the crash, on July 7, 2025.

The investigation identified that a sealant known as Loctite-515 was found in areas outside its recommended use. The misapplication of this sealant is believed to have reduced clamping force and allowed movement between engine crankcase halves, contributing to cylinder No. 3 abnormal operation and eventual engine failure.

Canada’s civil aviation safety alert (July 16, 2026) informed Lycoming opposed cylinder engine owners, operators, and maintainers about the potential for engine failure due to improper sealant application during assembly. The TSB urged maintenance personnel to follow manufacturers’ procedures and seek guidance from the manufacturer when procedures are unclear.