GRT Avionics

Ft-60 Red Cube with Sport SX has worked perfect for 2 years. Then on the next flight, it showed 0.0. Checked for voltage to cube, good ground..all good. Removed cube, solvent cleaned fwd and back. connect to EIS and create signal with light air through cube...you can hear the tiny turbine spin, but still no reading on EIS. I have ordered a new FT-60 to install and test. Anything else I have missed here? Thank you.

John Nielsen

You can test your wiring by taking the signal lead (not power or ground, the third one) and repeatedly touching it to ground. If there is no indication of a fuel flow signal on the efis, there’s a wiring or efis issue. If there is an indication, then the issue is inside the cube and you need a new one.
BTW, be careful blowing air thru. It’s easy to spin up the wheel way faster than it was ever intended to go.

Bob,
Thank you for the reply. I will try the test you describe today. i have a new cube on order, just in case.

What I have on the 3 leads from the EIS when it is powered up is the following:
Black: verified good ground (only 19 ohms to the - bat post)
White/Green: 5.7 volts DC (I thought it was strange that the signal input lead would have voltage on it)
Red/Green: 10.25 volts DC (Manual says it should be 12V 'regulated power'

Thanks again,
John

I hope that’s a typo: 19 ohms to the neg battery is a terrible ground connection. 19 milli-ohms might be acceptable. (Standard multi-meters cannot measure such small numbers).
Yes, the white/green is the signal wire, and yes, it sits around 5 volts. As the impeller rotates it is briefly grounded.