Tachometer problems

Sean, let's remember that a propeller in windmill is significantly more drag than one that is stopped in flight. In large prop aircraft the prop is put into a feather position to increase glide.  Just saying I still think the prop is the object we need to control. 

Cheers

Howdy Sean,

Hope all is well.

Quote:

"Just saying I still think the prop is the object we need to control."

I agree with RW on the prop importance which also directly affects the engine in several ways. Seeing the engine rpm in flight tells you several things vs seeing what rpm the prop is. I care more about the engine running and longevity over knowing what prop rpm on a gauge. Prop pitch the engine well and everything is good. Over pitch it and it can take its toll over time. Then it can get costly. Good prop pitch is like controlling your fuel mixture, proper spark plug temp range and gaps, balance on the prop, air intake and running rpm's. They all play a part in the big picture. Think of each one as a disease people could get. Like  contaminated blood (oil system), electric issues left unresolved (nervous system), smoking and doing things that cause cancer, ect..

They all play a part in our body over the many years so we try and do the right thing so we don't end our life too early.

So prop rpm and pitch understanding is important for longevity.

Jeff Blakeslee wrote:

Paul,

The fact that this has always been a problem makes me think it’s systemic rather than a part failure. I believe you need to know if Tecnam and/or Garmin has seen this on other Rotax powered aircraft using the GEA 71.  So, you may have to engage your Garmin dealer or Tecnam - as painful as that may be!  

With both engines now exhibiting this behavior this can’t be isolated to your aircraft.  The number of Rotax engines installed in certified aircraft with the G1000 must be very small, so this kind of thing has not had much chance to get worked out.  There are some folks on this site that are quite good with electronics, can you post a simple diagram of how the coils are wired to the GEA 71?  Maybe just markup one of the diagrams in the GEA 71 installation manual.  Good luck with this Paul.  

Sorry I guess I was maybe not clear that it is something that I noticed on another of our engines on another aircraft, a slight tick or instance where the tach showed a fluctuation that was clearly a false indication but hasn't been reported since it's first noted instance.   I am ready to run this engine to see if she's happy now that I have re configured the wire routing, I will keep this thread updated as for diagram, I will attach it here.

This is the old one and not the one brought to us by the avionics tech from Tecnam