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Fuel Flow Transducer Mounting-EXP 119

I'm not too thrilled about the mounting location and method for the FT60 transducer as shown in the plans. It is to be mounted on two large hose clamps around the intake pipes on the lower left side next to the oil sump. I think there must be a better way to install the device. I've read that others have moved it up near the divider, but would rather avoid new lines, etc.

I'll try to attach two pictures of the Plans recommended install, but just in case they don't come through, here is the question:
Just behind the transducer, on the left side of the oil sump, there are two drilled and tapped holes with a machined mounting surface that was designed for something (?) by Lycoming. Why not make a bracket secured into the two holes to support the transducer? Has anyone tried that method?

By the way, Raven (makers of inverted oil systems) tells me they've never seen this particular design sump and are puzzled as to how they could build an inverted oil system to fit it. Any experience, or anybody know if Lycoming is using someone to build this sump design for them?
 

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Randy---we did this for a client in the spring that wanted a mounting bracket install. WE modified that stock Vans RV14 hose installation to move the transducer forward slightly to mount on the bracket. He built the bracket and gave us the hose lengths he wanted.

Yes it can be done.

Tom
 

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Hose secure

1) On that last picture, with that big loop of hose, does the hose need to be secured with adel clamps to the engine mount, or is it better to leave as is for engine shake? I am going to have the same routing.

2) also, the fuel pressure hose is fire sleeved, is that necessary? My Vans supplied hose is not.
 
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John---he wanted the loop, and these were preliminary pics. Yes---at least 1 adel clamp would do.
On the firesleeving of the fuel pressure hose----we firesleeve ALL FWF hoses--except the MAP hose. Vans originall did not sleeve the pressure hoses or the cooler hoses. We felt that it was prudent to protect them. Pictured are our integral versions.

Tom
 
..we did this for a client in the spring that wanted a mounting bracket install.

I like the bracket, as compared to the adels on the intake tubes. I know the plans install works, but I hate to see the hose run so close to the exhaust headers.

---he wanted the loop, and these were preliminary pics.

Let's hope he changed his mind. There is no reason to have it, and at least one good reason to ditch it...the additional length is a fuel heater.
 
After few weeks of chasing a “why does fuel flow change with altitude” problem on an RV-14A, including replacing the sender and trying a new mount as other have done, we ended up moving the sender away from the per plans location. The problem went away. As a side note it seems others had the same problem. In short, the sender work fine until passing above 5K’-7K’. At that point the fuel flow sender sent in pulses to read a constant 11 or so GPH, regardless of throttle or mixture setting. The unproven theory is the reduce atmospheric pressure allowed the engine vibration to establish a weird resonance with the little spinning sender wheel.

The fuel sender installation instructions recommend not mounting it on the engine. I agree. The attached photo is how I mounted it on the RV-8. This location has proven to work well. I’ll do the same location on the new RV-10. Note the absence of 90 degree fittings on the sender - the smooth bent tube fitting is ok.

If you like, mounting the sender in the line between the throttle body and the spider always seems to work. Just be careful of hard mounting the sender via a fitting or such to avoid potential fatigue failure. In other words, I recommend retaining a section of flex hose on both the inlet and outlet of the sender.

Carl
2-D48-E7-E0-CF3-E-4-BF8-BBC1-A12264-D46348.jpg
 
Like it

Carl,
I do like it better on the mount, away from the exhaust headers (but it is in the oil cooler outlet flow).
Do you think there is enough length for the engine SHAKES?
Regardless of where I choose to mount the sender,I will need new lines. This means 2 of the 4 fuel lines that were part of the Vans firewall forward kit will need to be changed. ugh
 
As a side note it seems others had the same problem. In short, the sender work fine until passing above 5K’-7K’. At that point the fuel flow sender sent in pulses to read a constant 11 or so GPH, regardless of throttle or mixture setting. The unproven theory is the reduce atmospheric pressure allowed the engine vibration to establish a weird resonance with the little spinning sender wheel.

This is the first time I have heard of a problem like this on an RV-14......
We have never seen this on any of our 3 (built per plans) company RV-14's

The plans recommended installation was a compromise towards minimizing the length of hose, to minimize fuel heating.
I admit it would be better if the transducer wasn't mounted directly to the engine but that is why the cushion clamps were used (A bit of vib. isolation). The specified heat shield on the #2 and #4 cyl down pipes seems to do a good job of minimizing the heat exposure (we have tested with temp sensors attached to the transducer).
 
At that point the fuel flow sender sent in pulses to read a constant 11 or so GPH, regardless of throttle or mixture setting.

Carl,

I saw this exact same problem with my RV-7, IO-360-A1B6, red cube mounted to and between the #2 & 4 intake runners.

My solution was to change the 45° AN/NPT fitting at the cube to a straight fitting, reroute/shorten the hose between fuel pump and red cube, and eliminate the hose-90° at the fuel pump.

Glad to see that I wasn't the only one that ran into this :)

B
 
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I have installed mine using similar bracket mounted directly on the engine. The CUBE is mounted solidly and a bit farther away from the exhaust but I am not flying yet so we will see how it will fare. My last one was mounted per plan and it worked flawlessly.
 
Carl,
I do like it better on the mount, away from the exhaust headers (but it is in the oil cooler outlet flow).
Do you think there is enough length for the engine SHAKES?
Regardless of where I choose to mount the sender,I will need new lines. This means 2 of the 4 fuel lines that were part of the Vans firewall forward kit will need to be changed. ugh

For my install the oil cooler is firewall mounted on the other side of the engine (see photo). But, compared to exhaust heat I'd suspect a baffle mounted cooler would not be an issue.

This mounting location is on the fuselage side of the engine, so engine vibration is much reduced (the reason for not mounting it on the engine).

Hoses are easy to make. Just buy the parts from Van's. I have never used the Van's Firewall Forward kit so can't comment on that.

Carl
20191027-152343.jpg
 
Scott---we havent heard of issues with the stock RV14 style of install either, and chose a similar location for the RV10, since the flow divider location was somewhat prohibitive to what we wanted to do. Seems to be just fine.

Carl---we HAVE seen similar anomaly readings from many different install locations, plumbing, K factors, etc, including making no difference in altitude. No changes (according to the Savvy analysis) on RPM, MAP, EGT, CHT Fuel Pressure, but the flow would drop from 6.5 at cruise to 4.7 and stay there. IO320 RV9A. This has all been fully documented in previous threads.
After moving the FT60 to different locations with assorted plumbing, things would seem normal for several flights, then just when you think that all is solved, the little gremlins come out again. Even after replacing the FT60 with another unit, and starting the location processes over again. So I'm still not convinced that one install location is superior to another or we would use it for all of our transducer installs.

Honestly, we looked at all the common parts and installs, and the only thing I personally could come up with was the ' avionics translation box" or what the real term is for the magic box that takes the cube data and translates it the EFIS screen. I say that, because the only ones we heard about had to do with a specific avionics system. I was 99% convinced it was the magic box-UNTIL, we got a report from a builder that had similar anomalous data, and he was using another well known avionics system. Shot my theory completely out of the water.

So what I'm saying from FACTS on MANY transducer installs in MANY different locations and plumbing, that it appears that the location and plumbing arent as critical and something within the avionics system. We have NO test beds---other than these particular clients aircraft to test locations and plumbing theories, but not running parallel avionics to see what the deal is. As Ive also said, we are OPEN to doing an install with someone that has a better idea, to provide a once and for all solution to all of this. Carl---you may be the guy--but apparently you too have been chasing this gremlin. I'm still pretty convinced its avionics but cant prove it.

Tom
 
Carl---you may be the guy--but apparently you too have been chasing this gremlin. I'm still pretty convinced its avionics but cant prove it.

Tom

Tom,

We are in disagreement. Of all the elements associated fuel flow measurement, the avionics (digital) side presents the lowest probability of variance with changing conditions - it either works or does not work. Note - all my experience is with SkyView EMS, so I’m extrapolating to other similar EMS systems.

I suggest that cube location has multiple variables that without dedicated and well instrumented test stands we are only guessing at. Such as:
- Hose length to the cube and out of the cube.
- Hose bends
- Hose angles (WRT gravity)
- Fittings (stay away from 90 degree as I could only assume this induces some turbulent flow)
- Back pressure from the throttle body
- Heat
- Engine vibration

My experience is the conditions established a resonance that dominated the pulse sending from the cube to the EMS (as in the little wheel going around was no longer a strict function of fuel flow). But again, only guessing.

Bottom line is the majority of RV builders have not seen this problem mounting the cube on the engine. I did, and I found a repeatable process that solves the problem that should prove good for any RV install.

Carl
 
Does anyone have a pic of the stock RV14 mount?

With my IO370, Superior cold sump, and FM150 it seems the fuel line from the pump transitions to the right side of the engine. I would like to mount my red cube down low in that line. I'm trying to figure out the best way to do that. It seems there is plenty of room to attach to the sump in some manner.
 
...
With my IO370, Superior cold sump, and FM150 it seems the fuel line from the pump transitions to the right side of the engine. I would like to mount my red cube down low in that line. I'm trying to figure out the best way to do that. It seems there is plenty of room to attach to the sump in some manner.

You are right - there are lot of ways to do it. Here's one - see post #3:

https://vansairforce.net/community/showthread.php?t=160173
 
Micky,

I'm thinking along these same general lines. Just curious, did you position the red cube that far forward just so you had better access? Also, I'm not sure how the forward most fuel line routes into the throttle body. Do you have a pic of that?
 
Micky,

I'm thinking along these same general lines. Just curious, did you position the red cube that far forward just so you had better access? Also, I'm not sure how the forward most fuel line routes into the throttle body. Do you have a pic of that?

This might help a bit, I don't have another picture of that handy.

IMG_1640.jpg

I originally had a beautiful hose that went from the mechanical fuel pump direct to the fuel servo, and then decided to install the red cube after the mechanical fuel pump. So, I just stared at it for days on end to figure out the best place to put the red cube. I think this location was inspired by the RV-14 plans, but I may be mis-remembering this. Then I tried to figure out how to mount it. I decided I'd bolt it to the sump, but wasn't sure how. I decided to order the two hoses to replace the single long hose, and then fabricate the bracket to match the exact location of the red cube.

I was hoping to not have a red cube or other fuel flow transducer, since I was certain that the kind the F1 guys use - ultrasonic fuel flow sensors - would become available for us, but that has not yet happened.
 
Carl----I agree to disagree, but thats ok too. With multiple installs in various locations and various different planes, the common factor between all of the different installs 'appeared' to be the avionics. So my theory did not match the results, so you have to believe the results and invent a new theory.

Your solution works on your plane, but as we know, experimentals have a mind of their own, and not built exactly the same.

So maybe one day we'll have a test bed plane to try ALL the variances, and see what happens.

Tom
 
Micky,

This is very helpful, thanks. I'm in the same situation. I have the hose that was delivered on the engine, but like you I'll need two new ones.
 
Fuel flow intermittent

I started a new thread on this but you guys seem to have some answers here. My fuel flow usually works at start up the sometimes on taxi, sometimes on takeoff it quits working. Indicated zero. Then sometimes it works the whole flight. I have the standard setup on the left side of the engine with Advanced 5600 EFIS and Avidyne 540. The wires all seem to be in good shape. Do I need a new cube?
 
Funny, I just had the same thing happen to me. Exact same symptoms. Checked wiring and found no issues.

Luckily I happen to have and extra cube and plan on replacing it.
 
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