Desalination Washes: Keep Your Engine Salt-Free
By Pratt & Whitney Customer Service
Too much salt is bad for your health. The same goes for your aircraft engine. Salt and other contaminants can react with compressor components to cause corrosion. In the long term, this will affect their performance.
What Salt Does
When salt and sulphur—found in most aviation fuels—combine in your engine’s hot section, sulfidation can occur and corrode engine parts. Learn how to fight sulfidation in our related article.
Even when your engine isn’t running, salt can still get up to mischief by rusting and pitting the compressor. Magnesium components like the compressor inlet case and reduction gearbox housing are susceptible too. Eventually, this corrosion will reduce their efficiency, shorten their lifespan and raise your operating costs.
The Solution: Desalination Washes
Flush out salt deposits with regular compressor and turbine washes. How often should you do this? That depends on the operating conditions. If you’re in a salt-laden coastal environment for example, washing daily after your last flight is recommended. Don’t let the engine sit overnight especially in regions with high humidity as humidity increases the corrosion process.
Since the compressor wash will rinse salt deposits into the turbine, follow it up right away with a turbine desalination wash. If you’re concerned that you may not be washing your engine often enough, conduct regular borescope inspections of the compressor inlet case and turbine blades to check their condition.
How to Wash and Dry
For desalination washes, use potable water for the wash fluid. Unlike a performance recovery wash, you
shouldn’t use soap or other cleaning agents.
The reduction gearbox housing is also susceptible to salt deposits, so remove the exhaust duct drain plug during the wash to ensure all the fluid drains from the engine. Otherwise, it could accumulate and cause severe corrosion.
A post compressor wash engine drying run must be performed after the wash to completely dry the engine. P&WC's field experience indicates that stagnant water left in the engine for time periods exceeding the P&WC Engine Maintenance Manual recommendation could potentially lead to internal damage due to corrosion, including damage to bearings.
Consult your engine’s maintenance manual for all the relevant details. Besides desalination washes, you can also combat salt by using a P&WC-approved corrosion inhibitor. Talk to your P&WC representative if you have any further questions on the matter and remember, a low-salt diet is as good for your body as it is for your aircraft engine!
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