The Red Cube

Time: 2 Hours

To get an accurate fuel flow reading on my Dynon system I needed to convert actual fuel flowing to a digital signal. To do this I’m using the “Red Cube” transducer which will take care of this task. My way better half, Tricia, got this for me for Christmas! This girl knows the way to my heart…airplane parts! There are as many ideas as where to mount this as there are primer wars. I decided to follow Jason Beavers location and just put it just to the side of the fuel servo with a short fuel line. From the cube the fuel line will run vertically to the fuel divider “spider”. To start I needed to remove the lower cylinder baffle the AeroSport power installed as well as the oil return line so I could get the baffle out.

I will need to drill a hole in this baffle and place a grommet so the fuel line can pass through it. With the help of Glenn I measured the two lines, one from the servo to the cube and one from the cube to the spider. I’m using a couple aluminum fittings for the mock up and will put in stainless steal fittings when I assemble them.

I ordered the two lines from TSFlightlines, Tom is a great guy and answered every question instantly via email. They arrived just a couple days later and looked great. I really like how he uses a very tight fire sleeve which makes the line look great without a sloppy look. I first measured where I wanted the grommet and drilled the 7/8″ hole. I picked up some high temp grommets from McMaster Carr with the dimensions of 7/8″ for the drilled hole, 5/8″ for the center of the grommet and 1/16″ gap for the thickness. I drilled the hole with the step bit and cleaned up the edges and put the grommet in place. I then reattached the baffle retention bracket on the top of the cylinders after returning the baffle back between the cylinders. Darren at AeroSport showed me a trick to get this back in place. I used some safety wire around the hook. I pulled the wire up through the slot in the bracket and clamped my safety wire pliers on to it. This gave me a lead to pull the hook up with. Then I used a spade drill bit loaded into my adjustable screw driver and pushed down on the bracket while pulling up with the safety wire. Works like a charm!

I grabbed the first line and connected it to the servos elbow. I then screwed in the stainless steel nipple and elbow into the cube and connected it to the line going to the servo.

I then ran the second longer line down through the cylinders and the grommet connecting it to the spider elbow and the cube elbow. To help secure the cube I decided to use some .063″ thick aluminum to make a bracket. The forward spinner support, that I was planning on using, I used a piece of card stock to mock up this bracket. Then I transferred it to the aluminum and cut it out.

I drilled a hole to account for the wiring and match drilled the mounting holes. I don’t have the right length, AN4-17A, bolts so I used longer ones with a set of washers. This allowed me to make sure the bracket is good and I’ll order the correct bolts later.

I connected the hoses to the cube so I could mark the bolt hole from the sump. I took a the end of the bolt and marked it with a red sharpie. I quickly dropped the bolt in its hole and pushed so red sharpie ink would come in contact with the bracket marking the drill spot. After drilling that hole and cleaning the edges I returned the bracket to the cube. I reattached the hoses and bolted the bracket to the sump. Looks great and is very secure, it will look even better with the correct length bolts.

So now I will just need to run the wires and connect them to my Dynon EMS to show my fuel flow when the engine is running.

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