Engine Water Wash
 

Hello Everyone,

Was hoping someone would be able to explain what exactly is the procedure for water wash of an engine? What tools or washing agents do we use for water wash? what precautions and conditions need to be in place or observed?

Jet engine, Internal combustion engine, Rocket engine? Is it bigger than a breadbox? There will be local regulations for containing or treating the runoff and what chemicals are allowed to be in it.

Gas turbine internal wash? Depends entirely on the engine and installation, and whether the wash is for desalination or pressure recovery. Desalination; H20 only, make sure its clean. Power recovery, solution of a commercial chemical, such as Zok, always followed by fresh water rinse. Might need to be heated, depends.

Engine manufacturer will specify engine preparation, which might include blanking/disconnecting things like FCU sensing lines and removing igniter plugs, and de-preparation which might include draining some parts of the gas-path. Always followed by a drying/check ground run. Airframe manufacturer may specify blanking/disconnection of bleed-air feeds.

Prodedure and tools? Depends. Sometimes the engine installation includes compressor-wash plumbing with a quick disconnnect on the cowling, others may have a hand held spray lance. More often than not, supply is from a large pressurised set of tanks on wheels, such as from Tronair. At its simplest/smallest, an adapted fire extinguisher. Don't do it if the engine is too hot, or atmosphere too cold. Establish communication between cockpit and wash-guy; work out who is doing what, when, and for how long, and an "It's all gone to sh1te" signal.

Runoff? For water only; anywhere the real-estate holder doesn't mind the mess. Chemical; lets quote the good-old "local regulations".

Precautions? Its a rotating engine, act accordingly. Remember it may (or may not) have a propeller attached, which may (or may not) display varying levels of enthusiasm to rotate. Hazard data sheet for any chemical.

Try not to get wet.

Years ago I was asked to sit in as pilot for a comp wash on a Puma, which was a fairly new procedure. The ground crew had a converted fire extinguisher with a long lance for spraying the fluid into the open intakes.

The procedure was to start the engines one at a time and then use the roof throttle to control the engine at just above self sustaining rpm. It could be tricky because the water based fluid tended to put the flame out. The rotors were turning, hence the requirement for a pilot.

During the first run, I received an urgent “Cut, cut, cut!” signal.

The brass end of the nozzle on the lance had come off and gone into the compressor!

Lessons were learned. The new engine worked better than the old one….. :rolleyes:

Flying a GAF Nomad N22 on coastal survellience from Darwin in the early 1980's, often for hours below 500 feet and slowly note the salt building on the compressors of the piddly Allison engines, fine in the wet season if you could find a rain shower to wash them and restore the lost power.

No single answer as it depends on engine type and whether its a simple "water rinse" or "maintenance turbine cleaning action" as "water wash" has been used to describe both tasks. But in general, for a basic water rinse some engine OEMs allow it to be performed while the engine is running and some don't and usually doesn't require much prep to accomplish. On the "mx cleaning side" it can involve blocking various engine control and signal systems to prevent cleaning solution contamination plus repetitive water rinses to remove the cleaning solution prior to engine run. Regardless, most if not all engine OEMs provide written procedures for both tasks.

From my own experience on PW JT8s which we had to do periodically to recover performance.
Remove the generator cooling duct, blank it off. Disconnect the generator cables.
Have high power water hose on standby.
Dry motor the engine, when up to speed fire the hose down the intake for about 60 seconds, continue to motor to blow it through after water shut off.
Leave to drain for at least two hours.
Reconnect generator cooling duct and electrical cables.
Check start the engine and run for at least two minutes.
It's been a long time since I did this but that was the general gist. Clean water used, no cleaning agents.

Used to do a water wash on a Twin Otter every evening after the aircraft flew around the Channel Islands all day. Used De-mineralised water, blanked the P3 line and motored the engine for 30 secs. with the water fed through a spray nozzle in the intake.

I remember doing a series of detergent washes to try and recover a PT6 performance. After about 6 washes there was no improvement so I interchanged some instruments between the engines and low and behold the fault transferred to the other engine. I think it was Ng and Tq that both had errors

I remember these from JT9/RB211 days. Waste of time, made no difference.

Great to know. Thank you everyone. Much Appreciated

When I used to work on helo's in a tropical environment, it was a daily compressor rinse with water and once a week with the soap solution.
Compressor only, not the turbine.

I like this method
https://www.facebook.com/watch/?v=891717848108866

That's certainly not what the engine companies would say.
I was at more than one engine company maintenance or "Working Together Team" conference where they reviewed the engine company recommended engine water wash procedures - along with potential 'got-ya's' to watch out for (fume events related to improperly done engine washes were not uncommon). The engine companies quoted a 5-10 deg EGT margin improvement for a water wash (depending on how dirty the engine was).
I also recall a few lively debates regarding what to use - plain water, filtered water, or various soaps.

With particular regard to desalination, and from personal experience; without a complete, documented compliance with the OEM's recommended wash schedule you can kiss goodnight to any form of corrosion warranty.

Incidentally, from the Home Counties to the sands of The Outer Hebrides, P&WC consider the whole of the UK to be a "marine environment".

Yup had done lots of those, the Wessex Gnome’s used crushed up fine walnut shell to clean the engine, which we sprayed in during cranking.
i remember seeing a sorrowful Gnome that had the wrong grade sprayed through it and the sparkling clean blades were paper thin as a result. lol.

I remember reading an Army report about a "smart" pilot who was returning to base in his Gazelle. He knew the engine would need a compressor wash back at base but spotted a crop irrigation spray rig in use, in a farmer's field. He decided to use the spray rig as a giant comp wash and hovered under it.

Great idea...or it would have been if he hadn't flamed the engine out, hit the ground hard and bent the undercarriage!

Disconnect the PS3 line. Position spray manifold in the inlet cowl, position collector unit behind the engine. Dry motor the engine, turn the supply to the spray manifold on. Allow to dry motor, then switch the water supply off to the spray manifold. Let engine wind down, collect water sample to measure PPM (cannot recall exactly what contaminant). Repeat another couple of times, measured PPM will drop each time.

LEAP-1A: try to wash every 750 FC. Need to stick to this for the higher thrust rating engines.
CFM56-5B: wash annually. When fuel was cheap, did not bother on the A319's.