I've developed a glitch!

[SimonN]

Hi All

My Knight 3D seems to have developed a glitch over the last couple of days. I't been fine for the past 6 months so I don't think it's down to my PPM receiver (famous last words!). I know all about 2.4g etc but that's not an option at the moment so I'm trying to find the cause without going that route. I'm working on the theory that it's been fine for this long so something must have changed. I've had a good look over the heli and MAY have found the problem. I have a remote glow plug extension lead fitted which is attached to the frame (see bottom of the attached piccy). Well, it's worked itself very loose i.e. it wobbles. Could something like this cause a glitch? I've been doing some research and I know bad bearings can cause problems but I can't find anything else obviously wrong. It has a Hyper fitted, what about the rear bearing in that? Is glitching a sign that it's on it's way out?

Any suggestions welcomed, apart from the one about going 2.4g !!

Cheers
Simon

[Stuart]

PCM is one route, but its best to try and find it first.

Does the glitch occur only when doing a certain manouver ? or just whenever ?
Any crashes ?
How old is the heli ? - Have you changed any bearings at all ?
Any new unsual noises started lately ?

[SimonN]

Hi Stuart

The heli is about 6 months old, but only had about a gallon of fuel through it. I've never crashed it, and have never changed any bearings. The engine is older than the heli though, age unknown because it's was removed from a 2nd hand Sceadu. I was thinking it sounded noisy today, but I'm not sure that just wasn't paranoia. It's running sweetly, loads of grunt...

The glitch seems to occur once every couple of flights or so, the heli drops about a foot or two before resuming normal flight! Scary for a relative novice like myself. It does it whenever it fells like it, last time today it was just in straight fast forward flight about 30ft straight in front of me.

Thanks
Simon

[gazza]

Anything loose can contribute to or be the cause of glitches mate.
As can static from drivebelts, knackered bearings, poor routing of servo wires & aerials & poor electronics layout.

Good luck!!

[Stuart]

Does your remote glow's protective sleeve have wear on it with rubbing. A tip is to put some pieces of fuel tubing around sharp edges where wires can rub and wear down. Try a flight without the glow attached to the plug so start with a stick on the plug. Does the noise sound as though its the engine, I suspect your engine bearing needs changing and if its rubbing the back plate this will not help. Change the bearing and when you put it all back together pull the shaft all the way to ensure it doesn't touch the back plate when running. If you take the plate off you may find a slight marking from the crankshaft.

[SimonN]

Stuart / Gazza

Thanks to you both for your replies. I'll remove the glow extension completely tomorrow and give that a go. If it still does it then I'll pull then engine out and change the bearings. Is it normally pretty obvious when there worn? Should I expect to find lateral play?

Simon

[Stuart]

I've found they feel rough.....you can see how the wear is effecting the bearing by looking down the case and turning the crank. I would get boca ceramic bearings are the best thing these days.

http://www.bocabearings.com

Not sure who is the supplier/stockist for the UK.

[Stuart]

Just Engines are the UK guy's so says Boca site, pity Just engines site is about is bad as they get.

http://www.justengines.unseen.org/

Would be better ringing I suspect.

[SimonN]

Blimey Stuart, that site is truely awful!

Thanks for the link anyway, I'll have another look at the engine tomorrow.

Cheers
Simon