Fuel Flow transducer installation

[hilltop170]

Since I can't post pictures to a PM, I was asked to post a picture of the routing of the fuel line from the firewall strainer to the carb. The picture is how the IA routed my fuel line and it has worked very well for 245 hours. And I just noticed no fire sleeve was used on the fuel lines! I'll get that taken care of at the next annual.

Click on picture to enlarge then click again to enlarge further, but not much.

Fuel line routing with fuel flow transducer installed

[hilltop170]

I'd be really careful...I think your engine might be completely out of oil. There's almost nothing splattered on the inside of the cowling (so clean!) & on the engine surfaces

What brand is your flow meter instrument & transducer?

Aryana, you just can't see the mess under #1 cylinder valve cover in that picture, it has been an ordeal to stop the leak there.

I have the EI FP-5 if I remember correctly. Look at the "EI Digital Instrument Installation" thread for a picture of the panel where it is installed.

I just filled up yesterday and added 21.0 gal. The EI Fuel Flow computer said it used 21.1 gal.

[hilltop170]

They are definitely accurate and reliable. I use three different ones and they are all just as accurate. The only problem has been loose spade lug connectors in the wiring which causes unusually high flow readings. It is easy to fix and I think EI has upgraded the connectors so it should not be a problem any longer.

[GAHorn]

I'm glad your installation shows the fuel supply line to be continuously UP-hill from gascolator to carburetor.
I've seen some fuel supply lines which seem to "dip" between the carb and firewall/gascolator.... a DEFINITE NO-NO!

LOW areas along fuel lines collect WATER and can cause a sudden loss of power while the engine tries to swallow that stuff. It typically occures immediately after top-of-descent....or power-setting change when the change of flow-rate allows the water to move along the lines.

[n2582d]

What are your thoughts about placing the fuel flow transducer in the line between the fuel valve and the strainer rather than downstream of the gascolator? EI requires that the transducer be attached between two flexible hoses so the aluminum lines would have to be replaced or modified. Having two less fuel connections forward of the firewall in the engine compartment seems like a good idea but I’ve never seen one mounted upstream of the gascolator. Here’s pictures of the line under the floor.

[Bruce Fenstermacher]

Gary, we change fuel flow transducers on a regular bases on the Cirrus we work on. I've changed it twice on the same 182. I'd put it someplace you didn't have to remove the floor like in your photo or work through a hole. A replacement of the transducer there could bump the job of removing/installing the fuel valve from its position of the most PITA.

The Cirrus Continental powered aircraft have the transducer mounted on top of the #3 cylinder under the #3 air intake tube. Between all the fittings in the fuel system forward of the firewall for the fuel injections system, off hand I can count more than 18, they probably figure whats 2 more.

[n2582d]

Thanks for the advice Bruce. It’s valuable to hear from someone who’s had actual experience with maintaining and replacing these transducers. What’s causing these transducers to fail? Could it be the heat and vibration in the engine compartment? Of course, on a fuel injected engine, mounting a fuel flow transducer upstream of the gascolator wouldn’t work because it would also be measuring the excess fuel which is returned to the tanks. (I understand, in some installations, they add a second transducer to measure how much fuel is returned so the computer can subtract that amount from the total fuel delivered). But on the Cirrus isn’t the transducer placed in the metered fuel line?

[Bruce Fenstermacher]

Gary, can't say what goes wrong in the Cirrus transducer, nor could I say what went wrong on the one in the 182. On the 182, in the bad transducer, the vane moved with seemingly no friction, could be something in the creation of the signal sent. I was told to replace it so not much trouble shooting went into it after being reasonable sure the wiring was good. Cirrus transducers are between the fuel pump and the throttle/metering assembly.

[GAHorn]

Gary, can't say what goes wrong in the Cirrus transducer, nor could I say what went wrong on the one in the 182. On the 182, in the bad transducer, the vane moved with seemingly no friction, could be something in the creation of the signal sent. I was told to replace it so not much trouble shooting went into it after being reasonable sure the wiring was good. Cirrus transducers are between the fuel pump and the throttle/metering assembly.

WHAT../? You checked out the wiring BEFORE replacing the transducer..??

This reminds me of the many times I’ve seen repairs accomplished which had nothing to do with the problem…. Proving how IMPORTANT an owner’s communication to a Service-Writers job is. I’m thinking of how the Work-Order might have been written, perhaps such as: “Replace failed transducer”…. Instead of “Fuel Transducer appears to have failed, Troubleshoot and Repair.”
This is important from the pilot/ower’s point of view as well as the technician because if the owner tries to diagnose the complaint for the Service-Writer (or mechanic, etc) …instead of simply describing the Resulting-Problem/Issue…. and allowing the shop to investigate the Symptom….. it may end up being costly and the problem continuing.

COMMUNICATION…. That is the key!

[Avee8or]

Thanks for photo. I am installing one on my 53B and planned on mounting as you did. Good to have confirmation it works! Making the hoses tomorrow.

One note--EI says to firesleeve the transducer if it is within 6" of exhaust. With the Bartone pipes, there is no way to mount the transducer with more than 6" clearance, so i will firesleeve it in addition to the fuel lines.

The EI transducer on my 195 has been reliable for at least 10years for what it is worth.

[Avee8or]

Looking closer at photo, I see you mounted using a screw through the holes in the transducer (provided for mounting via a firewall bracket). EI instructions are to support the fuel line with a clamp within 6" of the transducer if it is mounted inline with the fuel line as in your case. I think your solution would reduce stress on the fuel lines and is a better approach.

[n2582d]

Varel,
I wouldn't be too concerned about stress on the fuel lines -- the transducer only weighs 5.3 oz. I believe they call for supporting the transducer by using an adel clamp on the fuel line because this attenuates the vibration to the transducer. Their instructions for hard mounting the transducer applies only for installation on the firewall. Further vibration dampening might be insured by using a teflon hose in place of the standard Stratoflex 111/Aeroquip 303 hose. E.I. says, "The Stratoflex teflon hose can be much more flexible and easier to route than most existing hoses. If you have a hard to fit installation, consider this hose." For reference, here are several pages of E.I. transducer mounting instructions:

E.I. Transducer Mounting (A).pdf

(71.91 KiB) Downloaded 19 times

E.I. Transducer Mounting (B).pdf

(78.75 KiB) Downloaded 13 times

In the little research I've done it seems that there are two primary manufacturers of fuel flow transducers for general aviation, E.I. and FloScan. It's interesting that Insight has 201 and 231 model numbers -- numbers common to FloScan transducers -- yet their photos clearly show E.I. transducers. I think this Service Letter may explain the change in the company they sourced their transducers from.

Regarding heat shielding for the transducer, I see that Insight shows a shroud around the transducer:

tf5003.jpg (22.85 KiB) Viewed 114785 times

J.P.I. shows the FloScan transducer encased in an Aeroquip Fire Sleeve.

JPI Transducer Mounting.pdf

(85.6 KiB) Downloaded 17 times

Another thing you might consider is adding heat shields to the exhaust pipes adjacent to the transducer. Aircraft Spruce offers them here.

[mmcmillan2]

Are y’all still running the glass gascolators? That’s what I have on mine.

[Bruce Fenstermacher]

Are y’all still running the glass gascolators? That’s what I have on mine.

I would be if I still had my 170. I have the same amount of fear in an accident the thick glass cylinder would break as I do a metal can would be dented or deformed, breaking the seal and leaking gas all the same.

[DaveF]

I still have the glass. I like being able to see if anything has made it to the screen.