ratcheting sound

[Bobs]

After flying today I developed a very noticeable ratcheting sound when I spin my main blades backwards. This is on a 50 V2 that's only a year old and never been crashed - yet. My guess is the one way clutch bearing but just thought I'd get some other opinions. I have a newer 50 V2 that I built this last winter and it does not make any noise when the blades are spun in reverse. Any ideas? Thanks. :arggg:

[cdrking]

Also another thing to check is the pin in the tail rotor shaft. It's the one held in place by the set screw in the very end of the tail shaft. If the set screw comes loose it can rub the inside of the tail case.

Just another thing to check.

Jeff

[Bobs]

Had that problem a while back but that's not it this time. Thanks anyway.

[JetCadet2]

If it is coming from the tail then it may be the bearing in the tail slider, i had the same problem replaced the slider and it was fixed

[Dino Spadaccini]

the tail pullly on the tail output shaft is somthing to look at

[Bobs]

The noise isn't coming from the tail and it only does it when the blades are going backwards. There's no noise when the blades turn forward.

[the collective]

How many clicks per one revolution of the rotorhead? That could give you a hint where to look...

[Bobs]

There's 42 clicks for one full revolution. What's that going to tell me?

[the collective]

Well, if it was something like 8 clicks or so per revolution, I'd look for something wedged in the clutch pinion, because the clutch pinion makes approximately eight revolutions for each one of the mainmast. 42 clicks per rev is a head scratcher for sure... there's 85 teeth on the main spur, so 42 clicks would seem like every other tooth is clicking on something, but that doesn't seem like a likely scenario to me.

Hmm... you mentioned that there's no noise when turning the main blades forward, how about if instead of turning the blades themselves, you turn the main gear in both directions? Do you then get the sound both ways, or only in the backward direction? If you get the sound turning the main gear in both directions, look for anything that might be causing a bad mesh between the clutch pinion and the maingear... you might even try dropping the engine and see if the noise is still present without the engine in place?

This sort of thing can be pretty frustrating... been there myself on more than one occasion. :(

[playfair]

The only things that are spinning "backwards" compared to forwards are the clutch bell/pinion and starter shaft. There are a total of 3 normal bearings and 1 one way clutch bearing that are turning.

My guess is is the pinion bearing interface, which is evident if the pinion can be wiggled at all.

[flyinfool]

Its close but the belt drive pulley is 41 teeth
I have seen a worn belt that was sticking to the teeth of the drive pulley.
Look close and see if that is happening.

[Bobs]

Thanks for all the suggestions. My computer burned up Monday so I haven't seen these replies until now. So far, the only thing that makes sense is the belt. I've taken the tail apart: it's fine. I've removed the main gears and everything seems smooth, at least without the belt connected. I'll keep you posted. Thanks again.

[Bobs]

Replaced the belt yesterday and everything is smooth again. Thanks for the help.

[Dreamer]

Your tail drive belt becomes directional after little use. If you rotate it backwards you will get a ratcheting sound as the belts teeth are no longer symetrical. :)