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-   -   Red Cube Firewall Bracket Question (https://vansairforce.net/community/showthread.php?t=118317)

HIIFLY 10-11-2014 07:06 AM

Red Cube floating
 
I just replaced my red cube Ft-60 at 168 hrs. It floats at the rear of my IO 360 after the mech. Fuel pump and before the fuel servo . It became intermittent and unreliable , so I bought one at AC Spruce . I know that the engine on shut down produces very high G's about 30 I have been told . It could be that the failure was caused by mounting it floating on fte fuel line and shakened to death ???? I still have it mounted this way as I never considered the mounting could have been the cause of it failing with only 168 hrs of use until following along on this thread. Something to think about ? :confused:

Warbirdsolutions 10-13-2014 09:41 PM

Red Cube Installation Clarification
 
Emailed Electronics International who builds the FT-60 cube about mounting preference. Daniel from Tech Support wrote me back to say that the cube can be hard mounted using the mounting holes or can float between the fuel hoses. Must be mounted downstream of All fuel pumps. If hard mounted you must use flex hoses in and out of the cube. Mounting should be on the same vibration plane which is to say a hard mount on the engine as opposed to the firewall is recommended.
This is the definitive answer to the question and not my opinion. The older fuel flow transducers prior to the cube were made of a pot metal material and were not strong enough to be hard mounted without cracking. I think this is where the free floating mounting came from originally. The cube was specifically designed for hard mount which is why it has mounting holes in the aluminum case.
Thought I would pass this along....
Brad

edneff 05-15-2015 03:50 PM

So I am getting ready to have a condition inspection done on my (bought, not built) RV7. It's only about two years old, but I have been getting obviously bogus readings on the Fuel Flow. I had the cowling off the other day and took a close look at the Red Cube.

It's mounted on the lower right firewall, more or less attached to the gascolator and then to the hose that goes to the engine fuel pump. I don't see any bracket holding it to the firewall. What I do see however is that the wire comes out of the cube facing straight ahead, and some insulation on the white wire is coming off, exposing the inside wires. This wire is barely touching the engine mount.


Picture is taken looking down and aft towards the red cube, gascolator on left.

Not sure what to do at this point but I want to have some recommendations for my IA when he starts work on the condition inspection...

Any ideas?
Thanks

lr172 05-15-2015 05:36 PM

Quote:

Originally Posted by edneff (Post 983158)
So I am getting ready to have a condition inspection done on my (bought, not built) RV7. It's only about two years old, but I have been getting obviously bogus readings on the Fuel Flow. I had the cowling off the other day and took a close look at the Red Cube.

It's mounted on the lower right firewall, more or less attached to the gascolator and then to the hose that goes to the engine fuel pump. I don't see any bracket holding it to the firewall. What I do see however is that the wire comes out of the cube facing straight ahead, and some insulation on the white wire is coming off, exposing the inside wires. This wire is barely touching the engine mount.


Picture is taken looking down and aft towards the red cube, gascolator on left.

Not sure what to do at this point but I want to have some recommendations for my IA when he starts work on the condition inspection...

Any ideas?
Thanks

You have three issues. I know that EI wants the wire facing up. They are not adamant about it, but I suspect it helps to eliminate problems. They did seem adamant about it not being at a high point. They want something higher than the cube on the exit side. Otherwise any air bubbles will foul the readings. In my case, I mounted on the firewall but cube was higher than the carb. I put a loop in the hose between the cube and the carb with the high point of the loop above the cube. Last, they are adamant that the cube sit between the mechanical pump and the carb/servo. Yours appears be be before it, though can't tell from the picture.

sLarry

edneff 05-15-2015 07:05 PM

Quote:

Originally Posted by lr172 (Post 983179)
You have three issues. I know that EI wants the wire facing up. They are not adamant about it, but I suspect it helps to eliminate problems. They did seem adamant about it not being at a high point. They want something higher than the cube on the exit side. ... Last, they are adamant that the cube sit between the mechanical pump and the carb/servo. Yours appears be be before it, though can't tell from the picture.

Thanks, sLarry. Without looking at the installation, I am pretty sure the cube is below the carb, it's at the very bottom of the firewall. In any case, it's definitely not higher. And right now, it's set up between the gascolator and the engine driven fuel pump, so I guess I need to figure out how to change the location to AFTER the pump.

Where are most folks installing the red cube in this type of situation? If I relocate the cube is it likely to start giving realistic readings, or will I have other issues that might be due to the white wire insulation gap?

thanks again.

lr172 05-15-2015 11:25 PM

Quote:

Originally Posted by edneff (Post 983202)
Thanks, sLarry. Without looking at the installation, I am pretty sure the cube is below the carb, it's at the very bottom of the firewall.

I think you may need to look closer. I have a 6A model in my garage and just looked again. The bolt on the nose gear leg is higher than the carb fuel inlet and your picture shows the cube above that bolt.

Either way, I would do some re-routing before replacing your cube to get accurate readings.

edneff 05-17-2015 07:26 AM

Quote:

Originally Posted by lr172 (Post 983243)
I think you may need to look closer. I have a 6A model in my garage and just looked again. The bolt on the nose gear leg is higher than the carb fuel inlet and your picture shows the cube above that bolt.

Either way, I would do some re-routing before replacing your cube to get accurate readings.

That's not the nose gear leg bolt, this is a tailwheel airplane... The location is the lower right corner of the firewall/engine mount.

edneff 05-18-2015 02:06 PM

Got this from E.I. tech support today, I am planning to check my G3X setup tomorrow. Interestingly, he said nothing about the orientation of the wire coming out of the cube.

"For the installation side, the transducer needs to be downstream of the fuel pump and have soft fuel hose in and out of the transducer. I do not believe that your installation location has anything to do with the issue you are seeing.

I have heard of this issue many times specific to the G3X. After speaking with a Garmin rep I am confident that the issue is a K-factoring issue in their instrument. Our transducers K-factor is 68,000. I believe that when the Garmin is programmed for that, the fuel reading will be too high. Recently the calls about this have been declining so I believe that Garmin may have made a change to their system (this is just an assumption based upon tech support calls).

I would first check to see that the K-factor is set to 68,000 in the G3X. If it is then I would recommend contacting Garmin and checking to see if they have a firmware update that fixes this issue. "

AAflyer 06-01-2015 06:25 AM

What about hoses?
 
I'm about to put in an order for a Red Cube transducer. Could someone please share the sizes and lengths of hoses needed to install it on my RV-8 with an IO-360?
Thanks

TS Flightlines 06-01-2015 07:07 AM

-4 downstream from the servo. Lengths??? where are you going to put it? That will determine the 2 hose lengths. There isnt a "'SPECIFIC LOCATION" . That would be too easy.
Tom


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