[bartman]

Just picked up the raven turbo cooling fan. I ordered the helimax version as it was easier for my LHS. The excellent instructions basicaly go like this,
1: Remove engine as per manual.
2: Install cooling fan.
3: Reinstall engine as per manual.
OK I'm exagerating but not by much. So here is my delema. The kit includes a very small washer (more like a shim actually). I dont know where it goes or if it is required for every install? I also have seen lots of fan runout and ballancing comments. Does the raven 50 require this kind of precision install? Thanks in advance
Brian

PS here is a link.
http://manuals.hobbico.com/hmx/hmxe4105-manual.pdf
and another
http://www.centuryheli.com/products/...&currentid=137

[cassat]

Yeah, kinda vague instructions....does the fan slide over the engine shaft? or thread on?
I would assume it goes under the shaft nut and is thinner so that you don't run out of thread on the motor shaft.

[Phil Noel]

That fan fits in the same place as the stock fan. When you removed the stock fan there would have been the same washer. That small washer is to go between the prop nut and the fan (see the Raven manual). Also of note is to be sure the clutch is securely screwed down all the way on the crankshaft and locktited (see the step in the Raven instructions)and that there is the proper washer-spacer between the bottom clutch bell bearing and the front engine bearing. You do not want them rubbing against each other while you are idling.

No, you do not have to do the dial indicating and balancing etc, on that system, because all of the major components - clutch, clutch bell and fan - are attached to one shaft - the engines crankshaft. This automatically aligns all these components and keeps all their weight very close to the front bearing, so minor weight discrepencies become relatively inconsequential.

On other system where alignment, dial indicating and balance become more critical, the clutch is on one shaft (the crankshaft of the engine) and the clutch bell is on a seperate shaft located in the upper part of the frame. As you can see it is critical that these two be aligned as accurately as possible.

In these systems, as the heavy clutch and fan is located on fan hub that extends all the weight well past the end of the end of the crankshaft, a fair distance from the front bearing, any slight imbalance will have a long moment arm to work through and cause high frequency vibrations.

[xv-townboy]

I have had this fan for a few months now..Just install it the way Phil describes and you wont have a problem..I just wish that you could see it a little better cause it looks so freakin cool *o)..Works awesome to!

[bartman]

Thanks everyone I'll let you know how it goes.