Fuel Flow sudden changes..Red Cube bad?

[rlallen1]

So after 800 hours I noticed my FF went to 25 GPH.. Never seen it more than 18 or so. On my next leg home I noticed on several occasions the FF went from 10 GPH to 20ish.., finally settling on its typical 8 GPH for the last few hours of flight home. No other changes noted, all temps remained the same.. etc, Red knob never moved.

I suspect my red cube is going bad, or perhaps the connectors need cleaned up.

Are the red cubes known to go bad and are they serviceable?..

Thx
Ryan

 

[kellym]

So after 800 hours I noticed my FF went to 25 GPH.. Never seen it more than 18 or so. On my next leg home I noticed on several occasions the FF went from 10 GPH to 20ish.., finally settling on its typical 8 GPH for the last few hours of flight home. No other changes noted, all temps remained the same.. etc, Red knob never moved.

I suspect my red cube is going bad, or perhaps the connectors need cleaned up.

Are the red cubes known to go bad and are they serviceable?..

Thx
Ryan

I went through this perhaps 3 years ago. I acquired my system back when all the connectors were spade connectors. They are very unreliable for fuel flow. Sometime ago, Dynon and Electronics International changed the fuel flow cube to an improved connector. Making the change improved things so much that my K factor went down a couple thousand. Go to https://iflyei.com/product/olc-2/
and order a 5 pack for $5, includes shipping and allen wrench needed. I later changed all my EGT and CHT connections with these and got much more solid readings. They are easier to use than crimp spade connectors and are re-usable.

 

[airguy]

I replied to your thread on this subject on VAF - it's most likely your connectors or wiring. Every time the wire makes/breaks connection, it looks like a pulse from the Red Cube. If that happens at a decent frequency (think vibration) you can get a LOT of additional false pulses.

 

[kellym]

I replied to your thread on this subject on VAF - it's most likely your connectors or wiring. Every time the wire makes/breaks connection, it looks like a pulse from the Red Cube. If that happens at a decent frequency (think vibration) you can get a LOT of additional false pulses.

Agree completely. Have had red cube on two different aircraft. All problems over time traced back to poor connections, broken wires, etc. Good connectors like the EI OLC-2 and proper support of wires are essential for reliability and accurate readings.

 

[rlallen1]

Thanks for the PMs.. As suggested and as I suspected it was the connectors. I noticed the bundle was sitting on top of the engine/sump and getting some heat. The ground wire was slightly melted probably started to make contact on the sump. Certainly suspect. I cut the 3 wires and recrimped them. After rebundling I wrapped them in some fire sleeve for an extra layer of protection. Test flight went fine..normal FF.. Wish all fixes were so easy.