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yankee-flyer

Well Known Member
Has anyone past the fly-off period "modified" their airplane with softer throttle opening springs? I see the need for the springs (pushing on a cable to get full throttle) but these require a LOT of friction lock to hold any RPM less than WOT.

Suggestions?

Wayne 120241 143WM almost
 
When I built the Zenair CH601HDS, I didn't like the cable operated throttles on the 912, so I built a "belcrank" of sorts for the firewall and converted the throttles to more conventional pushrods. That airplane now has over 1500 trouble free hours on it.
 
Be very careful, Wayne....

...that has already been done and the result was a totalled Zenith 701. He was short and added throttle to drag it to the runway....nothing happened and he went into the trees.

FWIW, you guys NOT building or flying the -12's, the throttle cable on the Rotax doesn't add power...the springs on the carbs do. When you move the throttle forward, you're allowing the springs to open the throttles, hence the discussion.

Best,
 
Throttle Springs

I don't like the spring arrangement either. I would like a change to solid wire push control so that the engine doesn't speed up if you let go of things, and with a solid wire arrangement you just push or pull as you wish instead of getting into some situation where the engine 'takes off' when you don't want it to...like taxi or landing in critical wind conditions. Weaker springs would help, but solid wire controls seem to me a better solution. Has anyone tried that?
 
The 701 and the RV-12 are quite different airplanes. The throttle springs on the 12 either require a whole lot of friction lock, or your throttle will creep. Either of these can create potential problems. If your throttle slips and adds power on short final, you will float. This is more likely to occur than a total failure of the throttle system such as experienced by the 701. I would not advocate removing the springs, but they don't need to be as strong as they are.
 
When I first flew the -12 I thought the springs were too strong and that I would change them. Today, I don't even notice it. I automatically adjust the friction nut to keep it from creeping. I would not worry to much about it until you have a 100 hours or so on the plane, then if you don't like it change out the springs.

JMHO
 
Actually

pierre smith said:
...that has already been done and the result was a totalled Zenith 701. He was short and added throttle to drag it to the runway....nothing happened and he went into the trees.

FWIW, you guys NOT building or flying the -12's, the throttle cable on the Rotax doesn't add power...the springs on the carbs do. When you move the throttle forward, you're allowing the springs to open the throttles, hence the discussion.

Best,
Click to expand...

The poor guy this happened to rebuilt his airplane and then a year or so later..it got totalled again..i don't know if it was for the same reason.

But yes be very careful, my 601 was plumbed the same way, the springs were a pain but I lived with it.

Frank
 
I like the springs...

At 25 hours I didn't like the springs; at fifty hours they felt very natural; at 100 hours I wondered what it would be like to 'dead stick' from 3,000 feet if a failure took the throttles to full power...so I tried it and it went just fine. At nearly 200 hours I like it just the way it is...I agree with Larry; give it a chance and I believe it will 'grow' on you.

Jay SluiteN124CS
Albany, OR
 
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