Hi Jon,
I have the Arplast and have had some vibration issues that sound similar
to your own.
I have found some wear in the small square nylon blocks and also in the
brass 6 mm actuator screw.
I am monitoring this and would like to renew these items.
Probably, I could make them ,but would prefer to obtain some correct
specification replacements.
The shouldered allen screws holding the nylon blocks are peened over in
the clamped collar and, therefore would require machining out to release
them. Correct spec. replacements would be required.
The 6mm brass screw would be fairly easy to manufacture but is pinned
into the drive dog and could be a bit fiddly to carry out.
I wonder if the new people may also supply the above items?
Cheers Ken.
G-CEKV KIT 19 370 hrs
On 09/03/2016 21:53, italianjon wrote:
>
> Hi Pete,
>
> Trust you're well.
>
> I don't need blades, I think :?
>
> I am still trying to track down this vibration issue, progress has been slow
over the last few months due to work pressures taking all of my time. Anyway,
the gearbox work has, so far, not revealed anything obvious.
>
> There is one point of concern on the propeller though. If I pull blades 1 and
3 outwards with a moderate force and try and twist the blade there is no play
- it is rigid. But on blade 2 there is a bit of play which I estimate could
alter
the blade pitch by 3 to 4 degrees. It seems to be a worn plastic block, that
sits in the swash plate. I even think you mentioned it when you had a look
at the propeller. At that time you noticed it and said it looked OK. But I think
it's worse now. If I recall, when we assembled it at yours, there was hardly
any play. I also think the vibration could be a little worse now as well, but
still not detectable by me sitting in the plane while on the ground. It does
appear when airborne, even one single circuit. I am trying to understand what
the different effects of a stationary, but spinning prop, and an airborne prop,
at velocity are; and if that could give me a clue.
>
> I am also trying to borrow a few vibration sensors from work to give me some
data to look at, instead of using Mk 1 eyeball :D
>
> The swash plates sits about half way up the plastic block, and you can see
> evidence
of wear/pressure on the plastic, which leads to a gap between the surface
that is not contacting the swash plate, and the swash plate itself. It is about
0.2 to 0.3mm.
>
> I have checked the blade track and that is almost perfect. It's less than 1mm
total deviation.
>
> So my thoughts are starting to think about a single blade flutter.
>
> It appears that if I could hold of a single set of dogs, or set of plastic
> blocks,
to replace the ones on blade 2, I could take up the play to the swash plate.
Then see if that works, by removing this pay on blade 2.
>
> I didn't have my camera with me on Sunday, but I was going to video it and
> send
it to you and ask what you though.
>
> Best
>
> Jon
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=453608#453608
>
>
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