I was recently asked by a customer, “Is it possible to wash my Pratt & Whitney engine too much?” The operator considered his inquiry to be silly when, in fact, it’s a very valid question. In fact, it’s important to periodically clean your engine as a part of preventative maintenance. And, if you operate your aircraft in adverse environments, such as air pollution and salt-water exposure, it’s very important to increase your wash schedule.
Chemical reactions with the fuel and heat can produce severe corrosion, which can be significantly reduced through regular gas path washing. Although corrosion is not covered by ESP or warranted by Pratt & Whitney Canada, P&WC does allow for the customer to determine their own wash schedule giving consideration to their specific operating environment.
A desalination wash uses water or water/methanol to remove salt and light deposits, but if the engine is experiencing a loss of performance, as indicated from ECTM Trend Monitoring, a performance recovery water wash will be recommended. Cleaning agents are used to remove deposits that cannot be dissolved by a desalination wash. Pratt publishes a list of acceptable cleaning agents, including a formula they developed called WCT (2 parts Witconate HC59B, 4 parts Carbitol and 1 part Triethanolamine), in chapter 71 of the maintenance manual.
It is very important to observe the maintenance manual requirements of using methanol when the outside air temperature requires mixing with the cleaning agent or rinsing solutions. As a practice, Duncan Aviation does not perform a water wash in outside air temperatures of less than 0°c / 32°f.
The answer to the original question is “NO.” Periodically, rinse the external portions of the engine and if you are flying in adverse environments, absolutely, increase your wash schedule. Preventative maintenance, especially when dealing with corrosion, will reduce the operating costs of the engines, the added expense of repairing corrosion and additional downtime.
To discuss this topic or any other topic concerning your Pratt & Whitney engine, please feel free to contact me at any time.
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