Hot idle roughness solved!

[Zuldarin]

I have just turned a little over 47 hours of flight time with my RV-9A and I have learned in explicit detail what "experimental" means. I have had a few issues that I am working through (some of which I have posted about before) but one issue now seems to be solved thanks to Tom at TSFlightlines. When hot my engine would pop and sputter at idle due to fuel flashing in the supply lines. I had originally mounted my flow transducer (red cube) low on the firewall. Tom suggested I try a new configuration he was working on where the flow transducer gets relocated to the inlet of the flow divider. He sent me the parts I needed and after doing some hot taxiing on Saturday I am calling this issue solved!

Not only does this new configuration protect the flow transducer from exhaust heat but it allowed me to remove the red-cube-to-mechanical-fuel pump hose. One less hose means less air flow obstruction at the cooling air exit! I think that is a win win situation!

Here is a picture of the new configuration.

Thanks TOM!

[n700jl]

Darin,
This might of solved your vapor in the fuel problem but I don't see any support for the red cube. With out support you will break one of the fittings over time! You could either support the red cube with some sort of bracket or move it behind the firewall! It would be great if some else could chime in on this as well in the name of safety!

[cajunwings]

I fully agree with the previous post, that looks like more mass than I would want hanging off the flow divider due to vibration concerns. When I installed these on Mooneys the fuel supply line came in thru the rear baffle and the cube sat on a steel bracket that mounted to 2 case half bolts. First one still going strong 15 years later. Will do something similar on my 9.


Don B A&P, IA

RV 9 rebuild in progress.

[TS Flightlines]

When I was initially thinking about this, I envisioned a bracket to mount where the lower bolt is on the flow divider bracket. Darin will probably test that part as he moves forward.
Plug goes out to Team AeroDynamix, that tested this location in various configurations last air show season.
Tom

[rbibb]

Concur some sort of support bracket needed. It is a critical item IMO as well in that, should it break there is 100% chance of fire. A bracket from the divider mount bolt to the red cube is probably the solution. If there is any appreciable movement between the red cube and the divider you run the risk of breakage at weakest point. That would be the fitting, IMO.

I'd fix it before I flew behind it if it were me.

[noelf]

Also, I believe the red cube instructions specify that the cube mounting be oriented such that the wires exit vertically upward so that any bubbles in the fuel can flow through the cube and not be trapped within the fuel cube.

[Brantel]

Compilation of the post from the manufacturer's employee on this board.....

Originally Posted by Mathew Sharp

As far as I know Dynon distributes both the FloScan 201B as well as EI's FT-60.

The FloScan unit is much more sensitive to the angles/fittings entering and exiting the unit. EI's unit does not care. You can run 90 degree fittings in and out of ours without problems.

JPI does not sell EI's FT-60

Maybe you can get Dynon to trade you for a FT-60?

Good luck!

Matt

Originally Posted by Mathew Sharp

You do NOT want to rigid mount the transducer to the motor (any part) using just a fitting. It is a huge safety issue. The fitting could theoretically fatigue and break. You absolutely need to have flexible line on both sides of the Floscan 201B or the EI FT-60 (that Dynon now utilizes).

After manufacturing/supporting flow instruments for a good number of years we have seen that flow transducers accuracy is typically better when mounted after both fuel pumps. They simply seem to prefer to have fuel pushed through them, not pulled through. The truth of it though is that many installation drawings still read as though we were still using the older Floscan 201 transducers. I have seen installs that mount the transducer between the pumps with claimed success. The Floscan units were much more sensitive in regards to mounting location, angles of fittings in and out, and attitude. Our new design will tolerate a lot more. Frankly we don't care if the thing flows straight up, or if you put 90-degree fittings in and out (FT-60 only) of the transducer. Just don't mount it upside down or flowing sharply downhill.



Hope this helps,

Matt Sharp

Originally Posted by Mathew Sharp

Hello All!

Your friendly neighborhood EI Tech support rep here!

There are really two issues in regards to EI’s specifications on flow transducer placement.

1. Accuracy of the output of the flow transducer.
2. Safety.

Issue one is pretty basic. After manufacturing flow instruments for a good number of years we have seen that flow transducers accuracy is typically better when mounted after the mechanical fuel pumps. They simply seem to prefer to have fuel pushed through them, not pulled through. The truth of it though is that many installation drawings still read as though we were still using the older Floscan 201 and 231 transducers. I have seen installs that mount the transducer between the pumps with claimed success. The Floscan units were much more sensitive in regards to mounting location, angles of fittings in and out, and attitude. Our new design will tolerate a lot more.

The other more serious issue is in regards to safety. We want to make absolutely sure that the fittings on the transducers never are subjected to conflicting vibration planes. The engine will flex in the motor mounts creating conflicting vibration planes between the engine and the airframe. This is why the “flexible line in” and “flexible line out” is called out so often. This is also why we don’t want the transducer rigid mounted, via a fitting, to a carburetor or fuel pump. A contradicting vibration plane will focus the energy directly to the fitting. It is our sincere concern that with the two conflicting vibration planes here could cause the fitting to fatigue and crack. This would be bad…and we have seen it happen….

On the bright side, we don’t care if the thing flows straight up, or if you put 90-degree fittings in and out of the transducer. Just don’t mount it upside down, flowing sharply downhill, or before the pumps.

Please let me know if you have any questions or if we may be of any assistance.

Matt Sharp

[FasGlas]

Everything about that installation is wrong.

[DanH]

I talked to the EI engineers a few weeks ago. FT-60 is to be mounted wires UP.

[MercFE]

Originally Posted by DanH

I talked to the EI engineers a few weeks ago. FT-60 is to be mounted wires UP.

Not an expert, but to be fair... The documentation I've found states it should not be installed with wires down and that the BEST situation is wires up.

http://dynonavionics.com/public_html...v_F-7_2013.pdf