The engine performance retention is tracked with a specific engine parameter, the EGT margin. It is used, through engine trend monitoring
Deterioration rate of EGT margin by 2 to 3°C per 1000 hours due to
Engine wear due to normal use , this normal deterioration rate can be reduced by reduced takeoff thrust application when possible
Engine performance is usually recovered with an engine performance restoration in shop. However, engine water wash procedure can be applied on-wing and help to optimize the on-wing time prior to performance restoration in shop.
Regular engine waterwash has been demonstrated as efficient to recover EGT margin on-wing with an average EGT recovery of 15°C (0.5 to 1% SFC).
Engine gas path water wash also called compressor washing is a recommended engine maintenance procedure.
Typically the washes should be carried out repetitively at approximately 1500 hr intervals, this represents around two engine washes per year for most operators.
Pressurized water is used to clean the airfoil surfaces in the compressor
engine water wash performed with hot water, detergent or classic water.
Author – Zinhom Mohmoud – Aviation Training Consultant