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RPM Drop D180

Jcurry

Well Known Member
Hey Guys,
I have the Dynon D180. My rpm's randomly fluctuate down and back up while doing ground runs. I have also noticed that if I do a full power run up as soon as I get the rpm green arc, I will get as an example 5200 for full power. After reducing power to idle and then going back up I will be 100 rpms short of 5200. Maybe a heat issue? Reductions in power and back to full power may increase rpms +30. I don't believe that I'm actually losing 100 rpm's and that this is an indication issue. It mostly only happens at full power on the ground during run up. Cruise rpm's
have little fluctuation. Ignition checks are perfect. Oil temp and pressure perfect. CHT and EGT perfect. Run up done into the wind.
Any thoughts appreciated.

Thank you
 
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Im having a similar issue with my Arion Lightning with a Jabiru 3300. Interestingly, this problem didnt exist prior to my most recent conditional inspection. But now it exists since the inspection. Something done by the A&P appears to have caused it and so far the source has not been found. If I get it resolved I will advise what the source was on my end.
 
mine does the same thing, even at 4000 to do the ingnition check rpm drifts, I've had my RV12 4 years now and it has always been this way. Doing run up into the wind makes no difference especially is wind is vairable and gusting. I just did my prop balance and sometimes I'd get 5220 and then next time 5180....I have added additional springs to throttle arm to help obtain more positive throttle settings which help with carb. sync. but I guess its just the nature of the engine to rpm drift slightly,,,
 
The legacy RV-12 has a tightly cowled engine. Ground ops should be minimized, especially to prevent vapor lock (ask me how I know). My guess is the engine is running hot on the ground (Cocoa, FL). Carbs may be retaining heat as well – might even be boiling the fuel in the float bowls. I doubt very seriously if D180 is indicating incorrectly. Magnetic pickup is running a timing algorithm and it should be spot on…
 
Installation manual calls for a 60k resistor on the Wh/Gr tach wire. Try 80K resistor & see if that clears it up. Note- you should comfirm your tach readings are accurate with some sort of hand held blade counter tach as it is common to get wrong rpm readings from this setup.
 
mine does the same thing, even at 4000 to do the ingnition check rpm drifts
The word "drift" perfectly describes what it does. Mine also does it at 4k as well. My plane has done this since I bought it 10 months ago. It's just slightly aggravating trying to adjust the prop...
 
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The rpm drift is tough when doing the prop balance, I have a Dyna Vibe classic unit and I average 3 runs to come up with the numbers I need, it's just the nature of the engine. My carbs are in sync, prop balanced to .03 and she runs very smooth.
 
I have noticed that I get RPM fluctuations when doing a run-up opposite of the wind. Early on, it was some cause for concern.. now I just expect it when the winds are not steady and I'm unable to swing the plane around and point into the wind.

Prop balancing was fun too and I ended up just waiting until a calm evening just before sunset. It was hard enough without that extra variable.
 
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