Re: 912 ULS rough running at 2350 to 2450 rpm
by Kevin Stewart » 5 weeks ago
Hi Gudmundur,
That's interesting, did you have an wear on the splines of the propshaft? That's what I had that gave rise to roughness at different RPM.
Re: 912 ULS rough running at 2350 to 2450 rpm
by Sean Griffin » 5 weeks ago
Alan's gearbox may have dog clutch wear, like Gudmunder however I suggest exploring the least costly/easier options before going down this track😈
Re: 912 ULS rough running at 2350 to 2450 rpm
by Gudmundur Alfredsson » 5 weeks ago
Hi
No there was no wear in the spline. I never found any debrief on the magnet.
People could hear the clanking sound from the plane when landing, I did not hear anything sitting in the plane but engine did shake a lot að the low rpm.
Earlier I had zinced the carb, put on carbs from other engine, balanced the prop with no result,
I have propeller from Kiev Propeller it's a heavy one.
It's possible to test with lighter prop, then you maybe don't get the "resonance" prop/gear, easy way if shaking stop it possible the gear.
I tried eProp, then this shake stopped but of course i fixed the gear.
Best Reg
GA.
Re: 912 ULS rough running at 2350 to 2450 rpm
by Allan Pihl » 4 weeks ago
Hi.
Sean, yes my idea was to try everything else first. $$ So i lend 2 carbs from a friend and put them on yesterday, syncronised them, and the roughnes stopped :-) So now i will take 1 of mine and put on and see what happenes. If it still is good i will take the other one and see.
This way i can perhaps narrow the problemt down to one specific carb. ( or both ).
i will have to take them apart again and see if i can find the problem
Gudmundur i am pleased you fixed the problem. I saw some youtube of mecanics telling of the problem with wear in the gearbox when operating it with low rpm. When i bought my plane it had 80 hours and ran with 4700 rpm in cruise. After a year i piched the prop to 4900 rpm. in cruise. 6 months ago i piched it to 5100 rpm. in cruise. In takeoff roll i can get 5200 rpm. now instead of 5000 rpm.
I will keep you posted ....
Best regards Allan
Re: 912 ULS rough running at 2350 to 2450 rpm
by Roger Lee » 4 weeks ago
Hi Allen,
Why not have an "experienced" carb overhaul person just do an overhaul?
There's a good chance just pulling them apart that you won't see anything. Overhauling a lot of carbs teaches you certain things to look for.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
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