Blades not tracking correctly but only on one side of the disc??

[jimbojetset]

When in the hover and viewed from behind the blade tracking on the left is about 10mm out but on the right it's perfect.

Head has a tiny bit of play but certainly nothing excessive. Mechanical setup is fine (checked this morning)... blades were balanced and undamaged (checked this morning) however I've just changed them for another perfectly balanced pair. Feathering shaft is straight and true (checked this morning) Head dampeners & thrust bearings look ok (checked this morning) I also turned the dampeners around before refitting.

Although they look ok, I suspect one of the head dampeners is on the way out... anyone else have any other ideas before I do another test flight ?

[KevDavies]

It wont be the head dampers jim because it would be out all through the rotation. Check the swash bearing is seated correctly and the swash isnt pulling apart. Ive heard of the swash failing on Trex's before now

[waveydavey]

Surely if anything is bent you would see the same in both sides. Isn't this correct with tracking as the blade hits the air moving through it you would get lift showing any play as it retards you would lose the lift. Actually thinking about it it could be worn dampers.

[RcRotaryMadness]

It wont be the head dampers jim because it would be out all through the rotation. Check the swash bearing is seated correctly and the swash isnt pulling apart. Ive heard of the swash failing on Trex's before now

+1

had the same problem with one side being out if tracking, was the swash plate that was failing, pull it off the model and check for play.

Matt

[RcRotaryMadness]

...I'm pretty sure if it was the dampeners it'd be out of track all round... If something's happening in just one spot on the rotor disk it's usually the swash plate that's the culprit.

I have known slightly bent rotor hubs to cause weird problems too but my money's on the swash as Kev says

[jimbojetset]

Thanks for the suggestions... very much appreciated.

Well whatever I did during investigation (including checking I lubricating the swash) seems to have cured it... the blades are tracking fine now... that didn't stop my engine dying whilst inverted tho... thought it was a bag of bits but managed to flip it and auto it down... tail blades took a beating but the heli is fine.

[KevDavies]

PHEW!!!! I was getting good at inverted auto's when I was trying to sort that Pumped engine!! Would always cut on me when inverted! I think Matt witnessed one when he came down Dunkirk LOL

But looks like you sorted it when you checked the swash Jim, But id look at getting a new bearing for it if I was you just to be on the safeside

[RcRotaryMadness]

Yeah Kev I witnessed a few autos that day lol!

Glad it's sorted for now but keep an eye on it, if its the swash it won't take long for the problem to return.

Also worth checking the rotor disc from all sides too, incase whatever you've switched round has simply moved the issue to another point in the disc.

[jimbojetset]

Couldn't find a separate bearing to order so a new DFC swash is on order instead... cheers...