The aircraft engine should be cleaned regularly in order to keep it performing at its best. While most commercial aircrafts wash their engines monthly, smaller personal aircrafts can go a little longer- typically once per quarter depending on use. Think of the aircraft as a vehicle. When the vehicle gets all salty and dirty because of the weather, it is taken to the carwash. Any time the aircraft is used, it is exposed to salt air. Regular cleaning is imperative.
First, a visual inspection should be performed in order to check for metal particles. All parts of the engine must be cleaned completely, and there are two main steps that need to be done in order to do so: Degreasing and Carbon Removal.
The aviation mechanical engineer begins degreasing by putting the component in, or spraying the component with, a special commercial degreasing solvent. If the engineer uses a water-based degreasing solution that has caustic compounds, immense care must be taken when rinsing to ensure that there are no remnants left behind after cleaning. The caustic compounds could cause oil foaming if left untreated when the engine is put back in use. A good practice is to rinse all of the materials that were cleaned with the commercial degreasing solvent in clean boiling water. The degreasing step assists in the removal of soft carbon, grease, and dirt.
The second step to cleaning the engine is carbon removal. Hard carbon deposits can only be removed when they are placed in a tank of heated decarbonizing solution. Typically, these solutions are either water-based or hydrocarbon. If a water-based decarbonizing solution is used, the same precautions and methods should be followed as with the water-based degreasing solvent (rinse with boiling water to remove any remnants of solution). The decarbonization process loosens most, if not all, hard carbon deposits that are still present after degreasing. If there is still hard carbon on the mechanism, scraping, brushing, or grit-blasting may be necessary. There are varying recommendations based on the manufacturer or certain parts when it comes to what materials should be used for grit-blasting.
It is smart to take note that you should not use the same cleaning tank for both steel and magnesium based parts. The parts made with magnesium can become damaged during the process.
Lubrication oil should be applied after cleaning of parts to ensure that corrosion will not happen due to the cleaning process.