Rattle in the boom

[new-heli-pilot]

I took a kind of hard crash landing earlier and now there is a rattling/squeaking noise coming from somewhere in the tail boom area. Sounds about like its underneath the horizantal fin. I want to fly it tomorrow for thanksgiving dinner, so if anyone thinks this would be a bad idea please tell me now.

[Coolice]

Hey,

Check your belt tension, almost certainly a rattle from the boom is the belt rattling inside it.

A fellow flier recently re-tensioned his belt and tightened up a few other things to, namely the main shaft locking collar to remove a slight up & down play in the shaft.
During the next flight a rattle could be heard from the boom, again we thought belt and tightened just incase. But this did not cure the problem, the rattle was still there and we were puzzled, as we could not tighten the belt any further thats for sure.

A quick scout around the forums revealed a problem with vibration can occur if the main shaft locking collar is pulled to tight, which was one of the things he'd done to remove the gap. He re-introduced the small amount of slop in the main shaft and all's well now. Indeed my own Swift, which is running very well and smooth has this small amount of up and down play in the main shaft area.

Also, check the proximity of your tail pushrod to boom clamp, especially if you have fitted the upgrade metal one as that is slightly bigger.
.

[new-heli-pilot]

How do I tighten the belt?

[Coolice]

Hey,

On the front of the boom, where it fits inbetween the two side frame halves there is the tail transmission gearbox. See it here for a view of it :

http://www.centuryuk.com/Products/Helicopters+Spares/Swift?pos=51

These two plastic halves bolt together top and bottom to clamp the boom.
The procedure to tighten the tail belt is as follows :

1. Loosen off the boom clamp on the rear section of the boom.
2. Now locate the above mentioned plastic halves and slacken off it's four screws. You will need to get to these from the top and bottom of the machine.
3. Now and this is where another person is advantageous, you need to pull the boom outwards away from the main mechanics to tension the belt within and hold it tensioned. This is where the extra person helps, as they can hold both the model down and put a reasonable amount of pressure on the boom to keep the belt tight while you re-tighten the slackened screws.

Tension wise, it does not need to be to tight, but by squeezing your finger down through the top of the machine at the rear of the canopy (by the gyro) you should not be able to deflect the belt by more than 2~3mm max.
A quick check I do is to hold the rotor head and try turning the tail against the autorotation bearing to see if I can apply reasonable pressure without hte belt slipping.
I have perhaps a little more experience than yourself and so use my experience to judge whats just right, to tight or not tight enough, but you will soon get a feel for it.

Remember the belt tension doesn't have to be set within one go and so take your time and you'll learn the corrct tension as you go along.
.

[Finless]

Also my vid here may help
http://www.helifreak.com/download.php?id=13948

Bob