Broken Throttle Springs

[rvbuilder2002]

Originally Posted by RFSchaller

Bruce,

I'm not sure Iget what you're point is with regard to spring orientation. Is there something critical I'm missing?

Rich

Yes, but only relevant if you are using McFarlane springs.

[Ex Bonanza Bucko]

The McFarlane springs come with an instruction....and a picture I think...that requires they be installed with the open end IN at both top and bottom. But I am not at the airplane now so I may be mistaken about the orientation....so just look at the picture or read the McFarlane instructions.

EBB

[RFSchaller]

Thanks for the explanation.

[Handclutch]

Here's something interesting. Had a flight I needed to do after spring broke. Remembered I still had the old springs from original throttle. Wondered how they might work with new vernier assist throttle. Installed them and did a ground run - worked fine. No creeping or need to constantly tighten friction nut. Went flying and very happy with result. I did tighten the friction nut a whisker but not sure it was necessary. Operation was virtually identical to that with new McFarlane springs. Easy to use and stayed exactly where it was set. I plan to leave old springs in place. They are robust and unlikely to break and I still have the advantages of ther new throttle.

Jack

[PilotBrent]

Originally Posted by PilotBrent

Per Scott's note on this thread, I'll be putting in a report to Van's on this but thought I'd mention it here.

Installed Vernier Assist Throttle Control 3/2015 obtained from Van's with the new springs provided. At 107 hours, the right spring failed (noticed it after flying for several hours just before last flight of the day during a quick peak in oil door). Don't specifically remember looking at it at beginning of the day but I generally take a good look through door before the first flight of the day and obviously didn't notice anything. Throttle moves back and forth just fine without it so I wasn't even noticing an issue flying. If it had failed on left side, I might not have detected it until next oil change. Left side spring looks fine BTW.

Appears to be a relatively clean break just at the bottom of the coils. I'll hang onto it in case Van's wants to inspect it themselves.

Discovered that the left throttle spring has now failed as well. That is both R & L failing in about 100 TACH hours of use. Posted a followup report to Van's engineering

[RFSchaller]

Still loving my Home Depot springs after about three years and more than 300 hours on them!

[Sink]

Springs typically break from excessive vibration and or the spring metal hardness is too hard which makes them brittle or they are being over extended. If McFarland springs show a break pattern then a call to them from everyone would be warranted to let them know. It can't get fixed if no one knows. The Rotax springs can break, but isn't common. Maybe McFarland needs a different alloy metal spring.

[Mich48041]

With all of that tension on them, no wonder they break. I love my modified (shortened) Century Spring part number 5553, no throttle creep.

[rjtjrt]

Just had annual on RV-12
Total 101.5.
Left spring broken.
Replaced with McFarlane 6822 springs, as only ones we had available here.

John