Compressor washes should be a routine procedure for those who maintain and operate gas turbine engines.
Albeit some engineers/A&P mechanics might consider compressor washes to be just another mundane task we must do “because it is written into our operations procedures” - but let’s consider how compressor washes affect turbine engine performance and life cycles.
The T53 engine variant is a free power turbine engine that employs a five-stage axial and single-stage centrifugal compressor driven by a two-stage gas producer turbine. Dramatic engine performance degradation occurs with the ongoing accumulation of airborne contaminants within the compressor module thereby reducing the aerodynamic efficiency of the compressor blades that can result in deteriorating engine performance, unsatisfactory acceleration and higher than normal Exhaust Gas Temperature (EGT).
Contamination, especially in high salt operating environments, can also lead to abnormal corrosion of the engine components. In order to maintain engine performance and reduce the corrosive effects on the engine, the debris that builds up in the compressor needs to be removed.
We do this through routine compressor washes.
Tips for effective compressor washes
A typical compressor wash involves:
- chemical wash (pre-mix product solutions that are biodegradable and non toxic or spray solvents into an engine with low core temperature),
- pre-determined soaking period (as required) a thorough water rinse followed by;
- an engine ground/drying run activating bleed air functions to ensure relevant accessories are also dried
Operators may choose to establish a wash schedule, the frequency of wash events relating to the amount of contaminants being ingested into the engine subject to the operating environment, while abiding by recommended OEM procedures.
First and foremost, always refer to the OEM procedures to ensure compliance with the specific engine type. The OEM specifies which chemicals can be used to wash the compressor, often referencing between a military specification or readily available solutions with a set specific chemical parameter. It is recommended operators develop a compressor wash schedule that best meets the operating situation IAW Honeywell MM references;
-13B/17 engines; 330.2 Maint. Manual, section 72-00-00, page 702
-L703 engines; 290.2 Maint. Manual, section 72-00-00, page 702