The S-0309-116 is an aircraft-grade elastomer O-ring used as a sealing element in fluid systems such as fuel, hydraulic, oil, or pneumatic assemblies depending on installation location. It is part of an aviation-controlled “S-series” sealing designation where the exact geometry and material depend on the aircraft Illustrated Parts Catalog (IPC).

In aviation use, this O-ring functions as a pressure-sealing gasket seated in a machined groove, maintaining leak-tight integrity under vibration, temperature changes, and fluid pressure cycling. Like other aircraft O-rings, it must match exact dimensions and material specification to ensure airworthiness compliance.

Key features include:

Aircraft-grade sealing O-ring (elastomer packing)
Used in fuel, oil, hydraulic, or pneumatic system interfaces (application-specific)
Typically fluorocarbon (FKM/Viton-type) or approved aerospace elastomer
Designed for high vibration and pressure cycling environments
Installed in static sealing grooves (flanges, valves, housings)
Controlled aircraft IPC/NSN part (not a generic hardware O-ring)
Must match exact cross-section and inner diameter (S-0309 series coding)
Resistant to aviation fluids, fuels, and temperature extremes
Used in certified maintenance and overhaul procedures
Airworthiness-critical sealing component