An aircraft comprising a cabin air system, a gas turbine engine including an engine core coupled to the cabin air system to provide compressed bleed air to the cabin air system and a cleaning agent supply connector coupled to the engine core to conduct a cleaning agent to the engine core, and a pneumatic coupling system including a first valve coupled between the cabin air system and the engine core, a second valve coupled between the engine core and the cleaning agent supply connector, and a controller coupled to the first valve, the controller configured to automatically close the first valve and block compressed bleed air that may contain cleaning agent moving through the engine core from moving into the cabin air system in response to receipt of an input associated with a cleaning cycle.