[MS19087]

As with many builders I am working my way through the trials of fitting an IO-320 in my 9A. I have worked out most issues and am now faced with the prospect of deciding if I should cut my lower cowl to add a blister in the area where the mixture arm rotates - I saw where other builder have done this. My question is how much room should I allow for between mixture arm and cowl taking into account engine start-up & shut down?? Thanks!

 

[rv9av8tr]

Engine twist

Actually, it's not just startup and shutdown, you would be very surprised how much the engine rotates over just due to torque at full throttle!

 

[kentb]

Hello Mark.

I didn't notice how close my linkage was until after my first flight. It wore a small hole right through the cowl. I cut around the point of contact and then flew again.

After I decided that it was not digging into the side any more I started with a layer of styrofoam 1/2 thick and then built up with glass cloth over this. I built up with glass and micro until I had a nice smooth looking bubble on the side of the cowl. I then ground out the stryo on the inside. I think that I have about 1 inch clearance between the control arm and the inside of the cowl now. There is a lot of rotation of the engine during normal operation (including start-up and shutdown).

I still haven't repainted the bubble yet, but have seen no more cracks from contact.

Kent

 

[thinkn9a]

do you already have a straight arm?

If you still have an offset,... consider going to a straight arm. Of course then you will be working on the FAB instead of the cowling

 

[HelioJoe]

Mixture

Hi Mark.........had the same exact problem with the 9A I built. Did not want to cut the cowling and add a bubble. What I did was reversed the arm straight up vertical. If you left it that way....when you pull the mixture "OFF" you would actually making it "RICH and vice versa. So I made a bellcrank to reverse the direction of the control cable. Was a helicopter mechanic long ago and we were always using bellcranks.
Basically looks like a "Z". Let me know and I'll draw it and send it to your email address. Works great and even the DAR thought it looked "Factory".

Best [email protected]

As with many builders I am working my way through the trials of fitting an IO-320 in my 9A. I have worked out most issues and am now faced with the prospect of deciding if I should cut my lower cowl to add a blister in the area where the mixture arm rotates - I saw where other builder have done this. My question is how much room should I allow for between mixture arm and cowl taking into account engine start-up & shut down?? Thanks!

 

[USCANAM]

Straight arm it.

I had a similar problem with my fuel injected IO-360 and the 9A cowl.
My first solution was to cut a hole in the cowl, then make a bubble to fit over it.
After I cut a small hole, then kept enlarging it so the arm had un-restricted movement, it dawned on me that maybe I could get a straight arm to replace the curved arm. Made a phone call, and had one in 2 days, plus also had a hole to repair in the cowl.



Hope this helps
Jack

 

[MS19087]

Thanks . . .

Thanks to all for your input . . . I do have the straight arm installed. This only leaves less then 0.5" clearance. I considered going the bellcrank route as well - now with everything hooked up I;m thinking a small blister will solve this issue and hardly be noticable. Thanks again to all for input.