hawk sport starter shaft will not turn

[mhamlett]

i have run 3 tanks of fuel thru my new hawk sport.
it sat for about a week and not the starter shaft will not turn when engaged.
turns freely when pulled up and disengaged. i took out the engine to ensure the engine would turn over freely and pulled the plug to ensure it was not compression problem. put think back together. same thing, engage the starter shaft and it will not turn.

any ideas.
i am a newbie, so dont be too technical.

[fhhuber506771]

The Hawk likes to "throw the clutch" when you start it. Occasionally it will just loosen enough that when you turn off the engine... it spns on up and you get the symptom you have....acts like the engine is stuck from the starter end... but playing with the facnksaft at the engine.. turns fine.

Unfortunately.. you have to get the engine OUT of the heli to retighten the clutch/fan unit... and the retighten the lock nut (reduced size prop nut spplied by Century)

There is no easy answer for a permanent cure. You have to be careful with the locktite or you locktite the crankshaft into the front engine ball bearing (very bad...)

I have had my best result (6 flights since last clutch problem..) by taking a belt (from around my waist).. wrapping the fan with it abd wrapping the loose ends arond a screwdriver to act as a "strap wrench" (you can buy one... but a belt works) and use THAT to hold the engine from turning while torqing the nut as tight as I could with a metric 4-way prop wrench.

Normally it was:: 2 starts... toss the clutch. dissasemble half the heli.. retighten...reassemble... 2 starts .. toss the clutch.

You got 3 starts.. you did well. :p

*******

BTW.. DON'T use the things you screw into the glow plug hole to try to torqe the nut tight enough... you can crack the piston before the clutch will stay on

[Googleplex]

To tighten the fan etc without damaging the engine, you need to lock the crank of the engine. This can be done a couple ways, but NEVER use anything to jam the piston - its hardened steel and hence brittle!

Method 1) - Tooth brush down the carby. Remove carby and stick the handle of a plastic toothbrush in the intake port on crank shaft. It will lock the crank and allow you to do the nut up as tight as you like without damaging it.

Method 2) - Lock the rear crank. You can buy a plastic insert for most engines to do this, but the plastic toothbrush is fine. Remove backplate of the engine and near bottom dead center on the stroke insert toothbrush past conrod and under the counter balance on the crank shaft. This locks the crank even better than tooth brush in the carby and is my preferred method as it doesn't run the risk of damaging intake ports. I have never had a clutch come loose when done like this.

-Tim

[Jeff H]

- its hardened steel and hence brittle!


Its AL, but that it symentics, its still fragile, never use a piston punch. A toothbrush in the crank is my favorite.

[/QUOTE]i took out the engine to ensure the engine would turn over freely and pulled the plug to ensure it was not compression problem. put think back together. same thing, engage the starter shaft and it will not turn.
[QUOTE]

If your fan is still tight, and the motor turns freely by hand, maybe your starter battery is too low to turn the motor over????

[fhhuber506771]

Actually.. these things can 'spit the clutch" up the shaft and since the clutch/fan assy is threaded n the crankshaft.. and there's a nut there... the darn thing can act tight and be spun a 1/4 inch up the shaft.

annoying beast about the clutch.. but its the only thing I had problems with in 2 years flying it

Well.. I blew a gyro and 4 of the wrong type servos... but...