Walnut shells have been chosen for the cleaning of valuable turbojet engines because of unique compounds that give them the durability to stand up to the elements of a turbine engine while providing the elasticity and abrasives required to clean the engine.
The environment the turbine engine is exposed to will determine the rate at which the engine should be cleaned. High salt and high humidity environments can rapidly degrade the efficiency of a turbine engine. Cleaning the compressor with a compound such as walnut shells will increase the efficiency and life-expectancy of the engine.
Attach a hopper with a control valve near the intake of the turbine. A hopper is typically installed as a gravity feed device with an electrical control valve that is controlled by a nearby bleed air valve, such as an engine anti-ice valve. Fill the hopper or injection system with quality walnut shells.
Start the engine and run at idle or the best operating temperature for cleaning as determined by the manufacturer. Lower compressor speeds may produce better cleaning due to less disintegration of the shells in the first stages.
Using the electrical controlled valve, introduce the walnut shells to the intake of the compressor. Control the rate of flow by adjusting the control valve and monitoring the turbine inlet temperature (TIT) or exhaust gas temperature (EGT).
When TIT and EGT have stabilized, usually at a more efficient rate, close the control valve. Allow the engine to operate for an additional five minutes (or manufacturer's recommendation) to ensure all foreign material is purged from the engine.
After engine shutdown, remove the hopper or injection system and restore any electrical connections used for controlling the valve. Restore any pneumatic changes that were made due to pneumatic control systems.
