EN 3909 defines the standard test fluids representing those commonly encountered in airborne and ground operations, including fuels, hydraulic fluids, lubricating oils, cleaning fluids, de-icing agents, fire extinguishants, and avionic cooling fluids. Each fluid has specified test temperatures and a three-stage test protocol.
The standard requires components to be tested according to the appropriate component-specific test method: EN 2591-315 for connectors, EN 3475-411 for cables, EN 3745-411 for fiber optics, EN 3841-405 for circuit breakers, and EN 4057-303 for cable ties.
The standard uses standardized reference fluids rather than service fluids to ensure reproducible results, addressing all major fluid families that aircraft components may encounter.