Compressor wash Caravan question?

[Just another canuck]

Just wondering what the position of the fuel boost should be at and why... I've now seen operators put it on and others not? I don't see how it does anything... lubrication perhaps???

[Tiger Moth]

I leave it on or in normal just for lubrication of the pump/fcu. Same goes for the old Beech birds that don't have the extra engine driven pump or the automatically on boost pumps. If your condition is in cutoff you are not getting fuel into the engine anyways, just to the pump/fcu so no need worry about a hot start.

[longjon]

Manuals??? we don't need no stinking manuals.

[Bulawrench]

I have seen a couple of descrepencies between Pratt engine manuals and Caravan POH.
We have instructed our pilots to keep boost pumps on while washing. Engine manual has
limitations if airframe boost pump is U/S,engine pump to go for overhaul.

[fortis risk]

Your pilots do compressor washes?

[B-rad]

yours don't?

[Meecka]

F@#K No!!!

[Just another canuck]

No engineer on site here, so I do the washes... did them at one of my other companies too. Now that you mention the FCU lubrication thing, I do recall that being the reason why we put it on.

Anyway, a couple more questions about it... we used to do it through one of the ignitor ports, but at my new company, we have a fitting that the water pump just attaches to. Is either more effective than the other? Is this even the same thing? Remember guys/girls, I'm just a pilot, so don't be too hard on me.

Also, what's everyone's opinion on when to do the wash... Pratt says after last flight of day, but I've also heard that can cause shock cooling within the engine and cause cracking/damage. We do it in the morning before the first flight here, but I can see how the other method would be more effective, if it does not indeed cause damage.

[wrenchturner]

Anyway, a couple more questions about it... we used to do it through one of the ignitor ports, but at my new company, we have a fitting that the water pump just attaches to. Is either more effective than the other? Is this even the same thing? Remember guys/girls, I'm just a pilot, so don't be too hard on me.

The wash that you do through the ignitor port is a turbine blade wash, where the one you do through the fitting at the back of the engine is a compressor wash, either a desalination wash or a performance recovery wash, not sure which one you are doing. Either way, the manual (which if you were an AME you would have access to and would have all this information, however, that is an entirely different discussion) says to allow the engine to cool below 65C, which takes a minimum of 40 minutes since last operation.

[Bulawrench]

Our pilots work with the AMEs.....It is a family.
The engine must be cool enough, hence having an AME present. It is only a compressor wash.
The power recovery washes are done by the maintenance group every 200 hours as recommended.
Doing the wash the next day is pointless unless you start with the caustic (approved) soap first to release
the salt. Removing an ignitor otherwise they get wet with longer than 20 sec rinse.
I am talking float planes and some seem to think of it lands in fresh water that the wash is not required.
It is the salt or industrial pollutants in the air up to 1000 feet that you are trying to remove.

[Cyclenut]

No engineer on site here, so I do the washes... did them at one of my other companies too. Now that you mention the FCU lubrication thing, I do recall that being the reason why we put it on.

Anyway, a couple more questions about it... we used to do it through one of the ignitor ports, but at my new company, we have a fitting that the water pump just attaches to. Is either more effective than the other? Is this even the same thing? Remember guys/girls, I'm just a pilot, so don't be too hard on me.

Also, what's everyone's opinion on when to do the wash... Pratt says after last flight of day, but I've also heard that can cause shock cooling within the engine and cause cracking/damage. We do it in the morning before the first flight here, but I can see how the other method would be more effective, if it does not indeed cause damage.

Do you use any type of tool to remove the Igniter or install the fitting?? If so, THEN FULL STOP! Only if you are working on your own Amateur Built aircraft, or your own aircraft in the Owner Maintained category can you continue.
This procedure is from a MAINTENANCE MANUAL, not a POH or Ops manual. It is not "servicing" as defined by CAR's 101.01
http://www.tc.gc.ca/eng/civilaviation/r ... 1-1104.htm
(unless you can do everything without touching any kind of tool!!) NOR is it in the exhaustive list of Elementary Maintenance under CAR 625 Appendix A
http://www.tc.gc.ca/eng/civilaviation/r ... a-2458.htm

Have your PRM explain how this procedure from a MAINTENANCE MANUAL is either Servicing or Elementary work, and if they even try, call TC and get their opinion on it.
A "pilot" should fully understand both of these definitions (especially if Commercial) and ANYTHING ELSE IS MAINTENANCE!

[Heliian]

Can o worms now? leaving the boost on is fine, just make sure that your ignitors are disabled. A compressor rinse or wash should also be fallowed by a quick drying run. I hope you're capping the bleed air lines while doing the wash too?

[Bulawrench]

use motoring switch for washes.
Interesting story: Ailine owner and sidekick doing washes with caustic soap
and leaving it in the engine. No maintenance background and no idea what they
were doing. Cost: $67,000 for one engine repair. Engine was first run and never overhauled.
A little knowledge is dangerous. Best to not get too deep if you don't like to read manuals.