Importance of Compressor and Turbine Washes

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IMPORTANCE OF COMPRESSOR AND TURBINE WASHES

The following is an excerpt from a Civil Aviation Safety Alert:

PURPOSE:

The purpose of this Civil Aviation Safety Alert is to reiterate to PT6A operators the importance of compressor and turbine washes in preventing corrosion and sulphidation.

BACKGROUND:

Operating experience has shown that corrosion and sulphidation affects the aerodynamic efficiency and fatigue life of compressor and turbine components. Corrosion can be caused by salt deposits (sodium) and other atmospheric pollutants. Sulphidation attacks the oxide protective coating of turbine blades and will eventually expose and attack the base metal. This will weaken the blade and can eventually lead to catastrophic failure.

Sulphidation is a chemical process between sodium and sulphur that occurs in the hot section environment of a gas turbine engine.

Most aviation turbine fuels contain sulphur in sufficient amounts for sulphur idation to occur.

Routine compressor and turbine washes can help reduce the damage caused by atmospheric pollutants by removing them before they cause corrosion. Compressor washes provide the best results if performed after the last flight of the day before deposits have a chance to do any lasting damage. Since sulphidation is dependent on temperature, there is no advantage to performing the turbine wash at any particular time of day; however, since the compressor wash will transfer deposits onto the turbine, it is recommended to do a turbine wash immediately following the compressor wash.

RECOMMENDED ACTION:

Transport Canada Civil Aviation recommends that owners, operators and other responsible agencies be familiar with, and follow the instructions detailed in P&WC Service Information Letters (SIL) PT6A-144 R2 (Compressor and Turbine washes as an effective means of preventative maintenance) and (SIL) PT6A-146 (PT6A-114 and -114A Compressor Turbine Blade Maintenance).

Defects, malfunctions and failures occurring on aeronautical products are to be reported to Transport Canada, Continuing Airworthiness in accordance with CAR 521 mandatory Service Difficulty Reporting requirements. – End

Link to the safety alert https://www.tc.gc.ca/eng/civilaviation/opssvs/managementservices-referencecentre-casa-2013-07-1790.html

It is for the reasons stated above that AMI designed and developed the AMI-TW60 and AMI-TW60AT turbine engine wash systems. AMI designed these turbine engine wash systems to be of high quality, reliability and at the same time to be cost effective to the end aircraft end user / operator. Although the safety alert above was directed to owners / operators of Pratt & Whitney powerplants the concepts and principals are the same for all turbine engines.

Side-note:  In order to preserve the content of the safety alert I did not alter the spelling of sulphidation.  U.S. references to sulfur, sufidation, sulfidation corrosion etc…  I find to be spelled with an f.  None the less compressor and turbine washes are a good idea, reduce operating costs as they extend the life a turbine engine and as you see from the civil aviation safety alert, they are also a safety of flight issue.  Fly Safe!

important compressor turbine washes!