General No elevator control

[treff]

I wonder if anyone as come across this problem before. I was doing hovering practice with the helicopter at around 2 foot off the ground when It started pumping up and down without me giving any input what so even. The heli jumped up about 4 feet then down, then up again. I chopped the throttle for a heavy landing. Can anyone give me a pointer to what could have happened. The weather was good, no wind so I discount this. This was pitch change but without any input. Any ideas would be gratefully received before I trash the head. Thanks guys. Cheers

 

[Lee]

First, and it may sound dumb, but i gotta ask. Are the main blades on the right way around? Don't laugh, it can happen
Is the main shaft collar secure?
I would be looking at the servos>RX>TX Sounds like a glitch in the Matrix. Check your monitor screen to see if the inputs are smooth.

 

[Westy]

I think you mean collective control..... ????? elevator is forward and rearward direction of the heli

 

[Derek]

something i'm curious about...maybe it could happen....are all of your servo's fastened securely? could there be a loose servo?

 

[treff]

Thanks for the replies guys, it's really appreciated. I will check all of the above. I am having no luck at all with this helicopter. I'm learning a lot about building and strip downs but not getting enough flying. I am going to strip it down and rebuild completely with a new head. If I have the same vibration problems then it is going to hit the rubbish bucket. I will then save my cash to get something that is better engineered. Thanks again. Cheers