Check your carb springs carefully !
So... I'm on my way to go fly this morning and I'm running through some emergency proceedure type things in my thoughts on the way to the airport. One thing that came to mind is what might happen if a throttle cable or spring breaks. As a result, while doing the walk around I payed especially close attention to the throttle springs and much to my dismay found one of them (on the 1/3 cylinder side) was quite worn, I'm guessing pretty close to the point of failure. Replacement parts are enroute from California Power Systems but I thought I'd share this heads up to check these springs closely on your next pre-flight ! ps! a recurrent nightmare i used to have, (before i stopped eating a cheese sam'itch before sleeping) was after take-off the throttle stuck wide open the ignition switch wouldn't work, the carbs leaned out i climbed above them big puffy clouds and still was climbing full bore , honest! pretty damn scary for some-one content to play in 'ground effect!
Comments
Good Catch George and a great checkpoint for all other 912 owners.
Kinda makes ya go HMMMMMM how many other areas may be in the same state of wear?
Thanks for sharing this out George even if I only have a 503, your keen awareness makes me think on checking stuff of a similar nature on my trike.
See you in Polson Man.
Geo that's shocking. Could easily be missed. that is spring steel and should not wear unless it's of poor grade. You might have some options . Sorry but that kind of wear on a throttle spring could cost you an e\o. I ve seen that kind of wear on muffler springs but on throttle that should not wear like that. Good example is my Irish setter dog run. If I use low grade spring steel the dogs back and forth motion quickly wears just like your picture. I switched to high grade spring steel which i think has other composite metals and the dogs have been running on that spring for years with no wear on the spring rubbing on the metal. You should never get that kind of wear on something as important as a throttle spring.
hey George good job I bet tabs is checking his right now.what hours would be on them I have seen that on the old carb return springs.it is not wear but vibration that causes that.would it stick at wot without them?
Wow George that is a great catch! No question that could be easily missed. I hate to think about the implications of that spring failure during climb out at WOT from some low flying some distance from a runway. If you had some redundancy in cable retraction say from a spring behind your throttle pedal that may not necessarily allow carb throttle arm to return to idle position, right? Or maybe I'm thinking about this incorrectly. What if there was tape or a zip tie on cable nut so that it is captured in carb throttle arm?
I may not be thinking correctly regarding how you'd throttle cable is connected to your carb. Very different from ones I have had. No surprise since I have never owned a 912.
Everything caused by engine vibration. The rubber ring on the needle jet helps it from wears by vibration. You might check them for abnormal wear, if you haven't done it for long time.
Thanks George! Good reminder to check these return springs. I had one on the choke circuit break off, caused a really rough running idle. Was yours choke or throttle? Looks to be throttle. Not sure if it would cause EO, but to keep the motor balanced you would have to come in with compensating throttle, you like to land fast anyway ;)
yeah, good catch! you can do my pre-flight anyday! most auto return springs have TWO dissimilar springs and i have never seen that much wear even with 200k miles on them. vw , with similar vibe situations don't wear like yours did. is the corresponding 'hole' that ate that supposably hard spring also about wore through? another wake-up call for us all, thanks george. ps, a recurring nightmare i used to have ( before i stopped eating a cheese sam'itch before going to bed!) was having my throttle stick wide open, kill switches wouldn't kill, i went through many layers of cloud till i could clearly see the curve-iture of the earth, my carbs magically leaned out. i tried reaching arround to yank plug wires etc, no luck, it even got cold! then my alaram clock returned me safely back to 'bed'. ( no more last minute snacks!)
is there an sb out on this for time of replacement