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N951AC test of fuel pressure and flow (Red Cube) before attaching forward top skin

KazooRV-9A

Well Known Member
Patron
Here's a test setup I made to test the GRT Avionics EIS inputs for fuel pressure and flow prior to riveting on the forward top skin. It would be much easier to fix any potential wiring issues before closing up the front.
The setup used an automotive low pressure fuel pump and a ball valve to control flow. Everything worked great.
https://youtu.be/Y1lflZ1ibtY

FuelPssr_Flowtest.JPEG
 
Bring that puppy over here! - I've got the -10 on AOG status while I try to figure out why I've lost fuel flow indication on my second Red Cube in under 100 flight hours.

Original cube died in the tunnel; replacement has now given up after 50 hours bracketed to the forward sump between the throttle body and the flow divider. I can test my proposed fixes using the priming flow into a jug atop the engine, but yours looks much more elegant.

My mechanic says you have to play Russian roulette with red cubes, replacing them until you find the magic unit with some longevity randomly built in. Expensive habit if you ask me.
 
My mechanic says you have to play Russian roulette with red cubes, replacing them until you find the magic unit with some longevity randomly built in. Expensive habit if you ask me.

That's not a mechanic, that's a parts-changer. And he's not paying the bills.
 
Oh, he's a mechanic, all right. Decades of experience building and flying experimentals and building engines for more than a few members here - and knows that a red cube is not repairable - just opening it breaks a potted wire essential to its operation.

I share his cynicism about these little buggers. But I'm enamored enough of having fuel flow readout (and the LEAN indication on the EFIS and the handy %HP calculation that Advanced Flight does) that I will fork out $$$ for yet another one to get those functions back. I've checked electrical connection integrity and I'm pretty sure I can hear the impeller spin when I blow in the line, so replacement seems like the sole remaining option.
 
Hey, a safety note is appropriate here. Tie both the airframe and the fuel jug to ground. Flowing fuel can build a static charge. The goal is to make sure the the various components all maintain the same electrical potential, so there cannot be a static spark.

Same rule applies to de-fueling.
 
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