Thread: High tachometer alarm on D120

I'm getting an intermittent "HIGH TACHOMETER WARNING" on my D120 of late. It goes off when the tach reading is normal for the flight conditon i.e. on climbout I'm showing 4850 RPM and get that alarm. Likewise, I may be at 5200 RPM in cruise and get that alarm. Any ideas?
BTW, never had such an alarm before the bird was in for an annual and the shop updated the Dynon boxes. I can't simply take it in to that service center because it's on a sod field, and we've got snow and ice on the ground here in the upper midwest. I'll appreciate any helpful thoughts. Thanks.

Bob

Hi Bob,

That alarm shouldn't go off unless someone changed the settings in you D120. Go into the menu and look to see if the program is set for the Rotax engine. I'd bet money it is not. As a side note, you should also have the latest update from Dynon which is version 5.2.

I've seen the High Tach alarm before, following the installation of the firewall blanket. The root cause was due to loose temperature probe connectors to the oil and CHT temps. The temps were showing as bouncing all over the place, and when they went low, it also resulted in the High Tach warning. I had the connectors redone, and all has been well since.

Thanks, Guys. The firewall blanket WAS installed at the same time as the annual. That was just before we started getting these erroneous readings on the D120. I think you've steered me to the source of the problem. Prior to this one, I was getting WILD fluctuations and warnings from the ammeter. That proved to be a grounding problem resulting from the installation of the firewall blanket. I'll follow up per your tips. I BELIEVE the service center that did the annual, etc. updated the firmware on the Dynons at that time, and I THINK it is the latest, but I'd like to check that out.Frankly, though, I don't know how to get into the D120 menu.If I can't figure that out, or get a steer from someone here, I may be back for some help. You've been very generous to provide it on many subjects, and I appreciate that.

The Dynon manuals can be found on line on at Dynon support. Easy to follow the users manual. Press the second button from the left. Press, more, then setup. scroll down until you get down to engines. Select engine, then it should say Rotax, if it has another engine listed or other scroll in that section until you find Rotax.

Roger,
I have a horn sound go off on LS any time my ASI begins to read knots up and until I reach 40kts +/- . I thinks it's the Angle of Attack (AOA) . It's done this since my D100 was repaired at Dynon. Can I turn it off?

Yes, you can turn the alarm off and or get rid of the AOA altogether in the menu. If you want to keep it you may need to calibrate it which is described in the manual.

CT Newbie

The only way to get the high rev alarm at 4800 RPM is if the oil temp is low. When the oil temp is too low for flight, the RPM red line automatically decreases on the D120, or D180. In the winter you may need a 2" strip of aluminum tape across the top of your radiator to solve this. You can increase the width of the tape for colder temps.

Older software versions did not have this feature.

John