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Fuel Flow Transducer (Red Cube, FT-60)

wirejock

Well Known Member
Does anyone have experience to share on the Aircraft Specialty FT-60 mount for injected engines?
I only know one, Jereme, who has installed it. I don't believe he is flying yet.
http://www.aircraftspecialty.com/rv-7.html
Screenshot_20201229-162056_Samsung Internet.jpg
 
Lotta ways to skin that cat (apologies to cat lovers, luckily neither of mine can read English). Mine lives betwixt fuel servo and flow divider. Latter in my case is on the pilot's side of the engine. Red cube is hanging in space, supported only by hoses. Flow is vertically up, wires emerge from the unit pointed straight back toward the firewall. Hoses are supported by mounts & adel clamps secured by the engine. This was an EI-approved solution, 1025 hours now and counting, no issues.
 
Per plans...

Between the engine fuel pump and the fuel servo inlet. As shown in the RV-14 plans (attached). I did this for both of my -7s with IO-360-A1B6 (Angle Valve) engines. I used straight steel AN fittings tho..

Works well, no issues with cavitation, heat, vapor lock, blah blah blah.

Cheers!
 

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Larry, I'm currently working with Tom (TS) to get that bracket to fit the way I'd like it. He has been very patient with me and excellent to work with. Here are some of the things I've learned so far during the process:

  1. Make sure you specify Lycoming or AFP. The brackets are different. Guess what I didn't do.
  2. The Lycoming hose between the servo and fuel divider will be too long once the red cube is installed. Wait until it's mounted before you measure and get a new hose. If you guess like I did, you will get it wrong and go through several hoses.
  3. Using Tom's "v1" design, I found I needed about 1/8" of shim between the bracket and engine case. This necessitated a longer bolt. Spruce part # 08-07453 seems to be the right size for me, but I have not final installed it yet. Tom will likely weigh in on this thread to mention he has a new version of the bracket coming soon that will eliminate the need for shims, but I didn't want to wait.
  4. When mounted as in your picture, you may find the straight fitting on the inlet side of the red cube is a little far outboard, and comes very close to the cylinder fins. I plan to mitigate this with a 45 degree fitting from the red cube, plus a 45 degree hose end, to ensure clearance and a "straight shot" down through the intercylinder baffle hole. The right fitting would be AN823-4-4 (steel) which is impossible to find online. Tom can hook you up.

Remember to plug the "gauge" port on the fuel divider, per SB 18-05-21.
 
After reading many threads about placement of the red cube and heat issues, I put mine on the cabin floor between the electric boost pump and the firewall feed thru. There seem to be pros and cons on all the placements. This one avoids the heat and vibration issues and has been accurate for me. I only have 150 hours on it so gotchas might arise in the future.
 
Lotta ways to skin that cat (apologies to cat lovers, luckily neither of mine can read English). Mine lives betwixt fuel servo and flow divider. Latter in my case is on the pilot's side of the engine. Red cube is hanging in space, supported only by hoses. Flow is vertically up, wires emerge from the unit pointed straight back toward the firewall. Hoses are supported by mounts & adel clamps secured by the engine. This was an EI-approved solution, 1025 hours now and counting, no issues.

Larry, you have yours mounted like mine.

Like you guys, same location, but have a soft mount made from baffle material.
 
Mine is installed at the lower engine side of the firewall. No additional insulation and very accurate. It developed a leak at the inlet after 20 hours. Initially i used permatex #2 on the thread. I was able to make another full turn at the fitting, now it should be ok. I suggest to use straight steel fittings if possible.
 
Red cube

Mine is mounted on top of my forward facing servo with a steel 90D fitting on the in side then a 45D fitting facing up feeding the spider. Tom proved the line from the 45D up to the spider and the other steel fitting. It is supported against the top of the servo with RTV. I have about 200hrs on this setup and always check it when I inspect FWF at every oil change. It has been rock solid so far.

https://www.dropbox.com/s/89g2p0m71qwjjvj/IMG_20180907_184015781.jpg?dl=0
 
There are alot of ways to do this. We opted for the flow divider location to eliminate 2 hoses in the install. 1 of those typically was pretty short and a critical measuerment. If it was off, then the location of the transducer was off, which threw everything else off. LOL----I cant tell you how many we did with guys asking if we could cut 1/8-1/4 off the short hose to allow it to fit. With that, I took another look to see what we could do about making life easier.

NOT TO SAY that ours is the bible on how to do it---alot of your installs work just fine. We took recommendations from several respected sources and came up with our solution. And yes----its had multiple revisions. WE are always trying to improve it.

Tom
 
Her is my version with materials supplied by TS Flightlines. Old style flow divider bracket. Makes for a really clean and well supported installation.
 

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After reading many threads about placement of the red cube and heat issues, I put mine on the cabin floor between the electric boost pump and the firewall feed thru. There seem to be pros and cons on all the placements. This one avoids the heat and vibration issues and has been accurate for me. I only have 150 hours on it so gotchas might arise in the future.

That's where mine is. No issues after 1845 Hrs...
 
John---like this?
 

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Risky

Yes. Has anyone seen any problems with one installed like this?
Seems a bit risky to me. That's not a lot of mass hanging out there, and it is supported as well from below with the hose to the fuel servo, but if it fails it could spray fuel in that area and start a fire. Not to mention the engine will probably stop. I really like the installation with the bracket.
 
I am still deciding to mount my FT60 transducer next to the fuel divider or at the firewall like this RV8 recently put up for sale. I am slightly favoring the firewall mount solution due to the low vibration.
 

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There isnt a right wrong location to install the FT60. Some work out better than others for plumbing, maintenance, etc.
AGAIN----we had asked EI 9 years ago, to give us a 'recommended' install location. "Nope, its experimental," was the reply. So with the help of Team AeroDynamix, whom we we sponsoring at the time, we tested 3 different install types and locations to see the feasibility of each one. After 2 airshow seasons and no issues, we determined that the FT60 (unlike the FloScan) didnt care how it was mounted, vertical or horizontal, angled adapters, or straights, angled hose ends or straights. It just worked. Also---inverted flight had NO AFFECT on the readings---so that told us that mounting with the wires up didnt make a difference. (If youre inverted the wires would be down anyway).

So for roughly 8 years, we worked with builders that located the cube in just about every location and position imaginable. In working with them, we found that locating the cube in most areas, required 2 hose assemblies. The hardest one was the low version, above the servo with a short inlet hose, and a longer outlet hose. Almost always the short hose was either too long or too short. So we worked out a way to eliminate the short hose by mounting the cube at the flow divider. It flew that way for 8 years, no mechanical issues or failures.

Enter Chris Hrabe that wanted a support bracket. Some of you may remember the threads. WE got some engineering help from Dan Horton on the original bracket for Chris, then created the billet version we currently have.

No disrespect to anyone, but there isnt a right way, but surely wrong ways to do it. And, for the fuel spray thing---YES certainly a bad situation. So is a loose fitting on the fuel pump, servo, or anywhere else in the system that could potentially spray fuel on a hot surface and cause a fire. And yes the engine probably would have fuel starvation and stop.

Is the Vans location on the RV14 (under the #4 cylinder) any better or worse? Is a firewall location better or worse? Is a cabin location like the RV10 better or worse? All have good points and not so good points, but ALL are compromises to acheive the same goal. WE just did it a different way.
AND YES, like most things, we are continuing to do revisions to this install to try an make it better. One last minor item---we were told by a European client that their aviation authority approved the flow divider location.
The acknowledged guru of mechanical injection liked it between the servo and flow divider, and testing showed that it didnt matter if it was mounted high or low. So for ease of assembly, we chose the high mount. Your location is a matter of preference.

Tom
 
SNIP
Is the Vans location on the RV14 (under the #4 cylinder) any better or worse?
SNIP
Tom

The short answer, worse.

A stock RV-14A with the flow transducer mounted per Van’s FWF kit instructions worked either perfectly, or it just failed to ~14GPH reading no mater what the fuel flow (as in pulling the mixture all the way to cutout). On top of this the problem would only happen when climbing above ~5000’ or so.

Replacement sender, checks on top of checks, no improvement. We finally moved the sender to another location off the engine and the problem went away.

I hear rumor this was not the only RV that had this problem.

The SkyView EMS install instructions are specific on not mounting the sender on the engine.

Here is how I mounted it on my RV-8, and will do the same on the new RV-10 project. It has been flawless since first flight (130 hours now).

Carl
55-BE527-D-6936-4-DF3-A15-F-4-D3-AA37-A38-DF.jpg
 
Carl---thats good information. We know of a few cubes that had electrical failures in the RV14 location. Broken wire at the body of the cube, even though there was the factory heat shrink sealing.
The readings on some of these units on some planes is a frustrating mystery. Rare occurances, but we do have a client that had a previous firewall location install that was doing an injection upgrade. He got our flow divider install kit to move the FT60. His readings were NOT what he had previously as was expected. So we moved the cube to a location near the servo, and still didnt read like the orginal install, but did read like the flow divider install. So, he decided to do some testing, and we moved the cube to a location between the pump and the servo. It read CLOSER to the original install, but not exactly, but closer than either of the others. CHANGED the cube to a new one---NO DIFFERENCES---even installed it in the other locations, and it matched those readings.

Flow is flow, and it didnt make any sense to us, him or the guru that we contacted. I will say that in the 8+ years of putting it at the flow divider, there has been 100+ installs, and maybe 5 that had some erroneous readings. Unexplained. Several changed cubes and recalibrated and it read 'normal' whatever that was.

So all things that seem equal are sometimes not.

Tom
 
Hello Tom, you mention above about some changes in the current bracket. Can you let us know what those changes will be and when the new bracket will be available?

Thanks!!
 
Mine is mounted in the same location as the OP's photo and working well for 4+ years. Thanks to Tom (aka Hozer) for excellent lines and installation advise.
 
HI John---We extended the slot for acces to the center bolt, removed some material from the bottom, and raised the roof on the insde of the cavity for alittle extra clearance for the transducer. WE also fixed a minor mismatch angle issue where our bracket meshes with the original Lycoming 75009 bracket. (Apparently mine was bent alittle different or other wise NOT exactly the same as others. So we made a couple of shims to temporarily solve the issue, but have the CAD drawing fix to make it all fit fine now.

WE are going to do a 2nd production run, but in reality really would like to move the last ones we have of the 1st run. We also made a few minor tweeks to the AFP bracket version.

Tom
 
What sealant did you use on the pipe threads? It looks black in the picture. Just curious.

Missed this question! I used Permatex #2 to seal the NPT threads (and the plug to the right). No sealant on the flared fittings.
 
My FT-60 Mounting

I tried a couple different mounting locations that others have used for my not yet flying RV-9A. I was not really happy with them. The last one I tried was under the engine near the fuel servo. I was concerned for it being so close to the exhaust pipes and heat. I even put heat shields over it and split a piece of fire sleeve for protection. Over time, the more I looked at that the less I liked it.
My solution was to mount it on the aft side of the rear baffle next to the oil cooler on a 2” x 2” x 3/16” upside down piece of aluminum angle I had laying around. An aluminum doubler on the forward side of the baffle to help support the load was riveted on that has two 1/4” plate nuts the angle bolts up to. A couple custom fuel hoses from TS Flightlines finished it up. It’s still gonna get hot back there but it’s not sitting on top of the motor or down below it near the exhaust pipes.
 

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Without getting too deep into specifics, there are a few practical rules.

Keep hoses short and away from pipes. Long hoses are fuel heaters. Long hoses hear exhaust headpipes can be fuel boilers.

If engine mounted, keep the cube close to the crankshaft. Increasing the radius, crank axis to cube, means increased vibratory stress.

Mounting between the electric pump and the engine driven pump usually proves to be inaccurate with the electric pump running.

Tom's Flightlines setup with the cube in the servo-to-divider line nicely satisfies all criteria. No extra hose, mounted close to the crankcase, no pulse exposure.
 
...
Tom's Flightlines setup with the cube in the servo-to-divider line nicely satisfies all criteria. No extra hose, mounted close to the crankcase, no pulse exposure.
Probably runs cooler, too.
 
My FT-60 Mounting

I tried a couple different mounting locations that others have used for my not yet flying RV-9A. I was not really happy with them. The last one I tried was under the engine near the fuel servo. I was concerned for it being so close to the exhaust pipes and heat. I even put heat shields over it and split a piece of fire sleeve for protection. Over time, the more I looked at that the less I liked it.
My solution was to mount it on the aft side of the rear baffle next to the oil cooler on a 2” x 2” x 3/16” upside down piece of aluminum angle I had laying around. An aluminum doubler on the forward side of the baffle to help support the load was riveted on that has two 1/4” plate nuts the angle bolts up to. A couple custom fuel hoses from TS Flightlines finished it up. It’s still gonna get hot back there but it’s not sitting on top of the motor or down below it near the exhaust pipes.
I’m going to position my cube and n a similar position.
Would you be able to give me the part number for the 1/4 NPT fitting that goes either side of the cube please 🙏
Thank you
Chris
 
Straight nipples are AN816-4-4 steel.
Tom
Tom, the 1/4 npt that screws into the cube, but doesn't it step down a size for the flared section of the fitting for the fuel line between servo and spider?
That fitting AN816-4-4 looks to be the same diameter both ends?

Thanks
 
Tom, the 1/4 npt that screws into the cube, but doesn't it step down a size for the flared section of the fitting for the fuel line between servo and spider?
That fitting AN816-4-4 looks to be the same diameter both ends?

Thanks
The spruce picture is wrong then, just looked on another site and it does step down, DOH
 
Pretty happy with how mine turned out, too!

After 12 comments we finally have one who answered the question asked :LOL: I almost posted a picture of how I installed my red cube but then realized he was asking for specific mount directly to the spider.
 
Straight nipples are AN816-4-4 steel.
Tom, the 1/4 npt that screws into the cube, but doesn't it step down a size for the flared section of the fitting for the fuel line between servo and spider?
That fitting AN816-4-4 looks to be the same diameter both ends?

I replaced the Red Cube on my RV-7 last year, shortly after buying the plane. I ordered two AN816-4-4 fittings from Spruce for good measure.

After removing the fittings from the old transducer, I was surprised to see a difference in the orifice.

Both old and new are steel fittings. Was the old (smaller orifice) fitting not AN816-4-4?

AN816-4-4 (1).jpg AN816-4-4 (2).jpg
 
Without getting too deep into specifics, there are a few practical rules.

Keep hoses short and away from pipes. Long hoses are fuel heaters. Long hoses hear exhaust headpipes can be fuel boilers.

If engine mounted, keep the cube close to the crankshaft. Increasing the radius, crank axis to cube, means increased vibratory stress.

Mounting between the electric pump and the engine driven pump usually proves to be inaccurate with the electric pump running.

Tom's Flightlines setup with the cube in the servo-to-divider line nicely satisfies all criteria. No extra hose, mounted close to the crankcase, no pulse exposure.
I thought the red cube wanted straight segments for a few inches before and after.. in an ideal installation.. plus wires on “Top”
 
FWIW & related - there is a possible issue with the wiring out of the cube & EI appear to know as later units have epoxy resin ? around the wiring where it comes out of the cube.
There were a few posts re the EI ‘failing’ & I had my doubts until mine failed. As I fitted the new one I noticed the difference (resin, as above) to the old unit.
My contention is the white plastic wiring cover is too stiff & when bent close to the cube it stretches & possibly damages the wiring ultimately causing a complete/ intermittent failure of fuel flow indication. My solution was to use a heat gun on the wiring to achieve the bend as I needed. YMMV.
 
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