Poll: Where is your red cube?

I'm planning to move the red cube out of the tunnel during the condition inspection, I have had erratic fuel flow numbers (+/- 0.5-0.7gph).

My tentative plan is to move it to the front of the oil pan, between the servo and the spider.

I've read old threads and done some searching, but just wondering where most people ended up putting it.

Mine is on top the engine-straight plumb into the spider -advise from Tom Swearengen of TS flightlines - he can provide lines- works perfectly for 70 hours now

Kevin

Mine is between the mechanical fuel and the servo. It?s not mounted to anything just suspended by 2 sections of fuel line roughly halfway between the pump and servo. I also covered it with a firesleeve that ACS sells for this purpose.

Thanks guys.

Any pics? Kevin, I'm especially interested in how you mounted the cube on top of the engine.

Todd - re: the firesleeve - I think I found it on ACS; how did you secure the ends over the fuel lines coming in each side?

Auburntsts said:

Mine is between the mechanical fuel and the servo. It?s not mounted to anything just suspended by 2 sections of fuel line roughly halfway between the pump and servo. I also covered it with a firesleeve that ACS sells for this purpose.

Click to expand...

Same here.

red cube position

Mine is on the line after the servo on its way to the spider, right in front of the oil pan. It is suspended on the fuel line with a couple inches of play for vibrations on both sides. It is right side up with the wires going straight up as their directions say. And I put a big piece of fire sleeve on it to protect it from rattling on anything like the engine. And also to contain drips if it leaks. You can see it here: http://www.mykitlog.com/users/category.php?user=sglynn&project=607&category=4664

Only 5 hours flying so far, but so far works perfectly.

TShort said:

Thanks guys.

Any pics? Kevin, I'm especially interested in how you mounted the cube on top of the engine.

Todd - re: the firesleeve - I think I found it on ACS; how did you secure the ends over the fuel lines coming in each side?

Click to expand...

Initially just a couple of hi-temp zip ties but later I added some safety wire just to be on the safe side.

sglynn said:

Mine is on the line after the servo on its way to the spider, right in front of the oil pan. You can see it here: http://www.mykitlog.com/users/category.php?user=sglynn&project=607&category=4664

Click to expand...

That's as good as anything I've seen, assuming the servo is installed outlet down. Adels at the pan gasket line, no load on the flow divider hardware. Good thinking.

I have an AFP purge valve attached to the flow divider, so a red cube hanging in the vertical feed hose adds to a load path cantilevered more than with just a divider alone. It's not insignificant; there's a pipe nipple between the divider and the purge valve. Long time back there was a mandatory AFP bulletin to replace the aluminum nipple with a steel nipple.

So, I opted for an hard bracket to hang the cube from a sump bolt. Will vibration kill it? I dunno, we'll see. It was on a vibrating firewall for 800 hours.

BTW, in the old location between the electric pump and the engine driven pump, it was inaccurate at idle, or with the electric pump on. No such behavior in this new location. Yes, I know the wires do not point up. Doesn't seem to care. Given the internal construction, I suspect they can't point down.

Recommended

sglynn said:

Mine is on the line after the servo on its way to the spider, right in front of the oil pan. It is suspended on the fuel line with a couple inches of play for vibrations on both sides. It is right side up with the wires going straight up as their directions say. And I put a big piece of fire sleeve on it to protect it from rattling on anything like the engine. And also to contain drips if it leaks. You can see it here: http://www.mykitlog.com/users/category.php?user=sglynn&project=607&category=4664

Only 5 hours flying so far, but so far works perfectly.

Click to expand...

Nicely done Steve! My friend mounted his in the same location and suspended the same way on his RV10. The 540 has more room up there: recommended. 300+ hours and never a hiccup.

Insulation is a very good idea, mine (-7) is not insulated, but the measurement of temperatures of fuel along it's path is not done yet. I have a couple of times where temperature may have caused a drop in fuel pressure, but believe not related to the cube.

For what it?s worth, one of the coolest places FWF you can locate the cube is in the plenum. I rigged up a thermocouple and tested air temp in a variety of flight configurations and taxi conditions, including an hour long flight followed by a long taxi when it was 104d F.
I was shocked at how little heat is gained even after shut down. Airflow from a spinning prop at idle, or simply turning the aircraft into a slight breeze, even at 104 degF day, probably more on the ramp, has an immediate and surprising reduction in plenum temps.

Firesleeve buries the fittings. I like to inspect these regularly and can see them thru the oil door. You don?t need it in my opinion in this location based on my testing, at least for heat reduction purposes.

JonJay said:

For what it?s worth, one of the coolest places FWF you can locate the cube is in the plenum. I rigged up a thermocouple and tested air temp in a variety of flight configurations and taxi conditions, including an hour long flight followed by a long taxi when it was 104d F.
I was shocked at how little heat is gained even after shut down. Airflow from a spinning prop at idle, or simply turning the aircraft into a slight breeze, even at 104 degF day, probably more on the ramp, has an immediate and surprising reduction in plenum temps.

Firesleeve buries the fittings. I like to inspect these regularly and can see them thru the oil door. You don?t need it in my opinion in this location based on my testing, at least for heat reduction purposes.

Click to expand...

FYI, my cube is covered in firesleeve for fire protection as the cube's body is made of aluminum not because of a desire to protect it from normal operating temps. Since my fuel lines are firesleeved and have steel fittings, it seemed prudent to at least attempt to protect the cube in the same fashion (minus the steel of course).

Auburntsts said:

FYI, my cube is covered in firesleeve for fire protection as the cube's body is made of aluminum not because of a desire to protect it from normal operating temps. Since my fuel lines are firesleeved and have steel fittings, it seemed prudent to at least attempt to protect the cube in the same fashion (minus the steel of course).

Click to expand...

I don?t think there is a right or wrong here, just a choice between inspection vs fire protection. I chose ease of inspection as being more important for me,
You don?t need it for temperature reduction if installed in the plenum which is a common reason folks wrap it up.
Mine used to be wrapped. At the advice of a well known fuel hose supplier here at VAF, when I converted to Teflon, the firesleeve went away.....

After the servo, suspended in front of the oil pan, not firesleeved. No problems in 250 hr.

Mine is in front of the oil pan. Excellent precision . When i talked to airowperformance, Don said that it should not be on the succion side.

Where it is now, excellent stability in the reading. Electrical Fuel Pump on or off. No regret. Before fuel flow was jumping up with boost pump ON.

I also changed for the new style of airflow performance fuel pump. A lot less fitting. Straighter fuel line.


Lan Vinh Do