christer buschmann

I have a Raptor 90 with a strange problem.

When idling the engine gives away a distinct metallic sound, just like
something is loose inside the muffler. You can also hear the sound when
turning the engine with the electric starter.

I have tried everything to remedy the problem.

Things I have tried to change:

- OS 91 with two different Hatori mufflers, sound present.

- OS 70 with two different Hatori mufflers, sound present.

- YS 91, new muffler, new metal cooling fan, sound present.

- Taken out the rotor and clutch bell assembly, sound present.

- Removed clutch, only engine with cooling fan, sound present.

- Taken engine out, running in my hand with cooling fan only, sound
present.

- Mounted engine on a piece of wood, sound present.

- Changed the metal cooling fan with a propeller, sound NOT present
???

Seems like the sound is coming from the cooling fan ?

I have tried three different metal cooling fans !

I have tried to mount the cooling fan with and without the washer between
the engine and fan.

Please advice !

Christer.

bastian

The engine makes the sound while mounted to a piece of wood?
Seems like that should narrow the problem down to paranoia if it
happens to all your motors and it's not even connected to the
helicopter. I dont see how the fan could make any noise since it's
statically mounted to the drive shaft - unless it's unbalanced.

Perhaps it's just because the helicopter is idling with almost no
load. Try to see if you get the sound with nothing mounted to it at
all.

the vail family

Have you taken the back plate off and looked to see if the crank shaft is
tapping on it? Heli's don't put any thrust load on the crank. Is there any
end play in the crank?

Bill Vail

david

present


God hates helis, loves planks.

D

christer buschmann

"Bastian" <usenet@net-express.com> skrev i melding
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It's not the fan, the sound is also present when using a plastic fan, tested
yesterday.

The sound is _VERY_ distinct, it sounds like something is very wrong with
the engine.
Tested yesterday with a OS 61 WC engine, sound not present, not at all.
Same fan, same muffler etc. Maby I should stick with planks...

Christer.

christer buschmann

"The Vail Family" <wjvail@netdoor.com> skrev i melding
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any


Yes, there is no free play in the crank shaft at all.
No marks on the back plate.

Christer.

christer buschmann

Hehe. God let's me use the OS 61 WC engine, it sounds like it should.

Christer.

bastian

I say just bolt her on and fly her.
Maybe it will go away.

beav

Or the OS motor -)


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
http://www.beavisoriginal.co.uk

beav

Nah, God loves heli's so much he makes them turn themselves into lawn darts
so they die and join him in heaven. He must have ****ing millions of the
things by now


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
http://www.beavisoriginal.co.uk