FT-60 Fuel Flow Transducer Bracket

Time: 1.5hrs

I made up a fairly simple bracket for the FT-60 Fuel Flow Transducer. I originally had just a temporary L shaped bracket and I was going to just replicate that in some thicker aluminum, but after looking at how close the aft mounting hole of the FT-60 sat to the bend I decided to make it a little more complex and extend the flat portion of the bracket by making a cut pretty much up the middle of the bracket so I could bend out a small section on top. I also made the bracket a little wider than the original and made the height adjustable. I noticed also that the bottom mounting screw hole so that it will slip over the screw (that mounts the Rotax 3-way solenoid to the airbox. I did this because it’s almost impossible to put that bottom screw back in with the bracket on. Now only the top screw needs to be removed (and the bottom loosened) to get the FT-60 bracket on. The only thing I have in question is that from a little more reading it seems that you’re not supposed to have a 90 degree bend in the fuel line within 6″ of the FT-60 and I have like 3 of them. The TAF way only really has one (coming off the fuel pressure regulator). I guess I’ll need to do a test to see how actuate the FT-60 is in this arrangement. If it’s not I can always reroute the fuel line to loop around rather then using the two 90 degree fittings.

I’ll be writing up a complete step by step on how to install the fuel lines and what fittings go were when I do the fuel line install.

Here’s the layout of the bracket. I cut out a 2 1/8″ x 4  3/4″ piece from a sheet of 0.09″ 6061 aluminum.

A few photos of the bracket. I notched the bottom hole so it can slide over the mounting screw. And I also made the mounting holes adjustable to accommodate the short hose run.

Side view of FT-60 on the mounting bracket.

After facing view. The bracket uses the same mounting screws as the 3 way solenoid that mounts to the airbox.

Top view

EGT Sensors and Fuel Lines

Time: 1.5 hrs

The new EGT sensors came a few days ago and today I had some time to fit them. I think the new sensors will work better. These have a shorter lead so I purchased some K Type wire to extend them. they are also a bit easier to remove since the bolt holding them in is separate from the sensor body so you don’t have to turn the whole sensor (including the leads) to get it out. The only thing I don’t like as much is that the sensor has a 90 degree bend and so I can’t route the wire the same way I had routed it with the old sensor. I think they may work better on the front mounting holes, but from what I read the rear holes have a bit more accurate reading so I want to keep them in the back. I think the way I mounted them should work OK. I don’t want to take too much of the bend out of them in fear that I’ll break it.

NOTE: I thought I had a photo of the installed EGT, but I guess not. I’ll take one tomorrow and upload it.

The other thing that came were the fuel lines. Wow these are excellent quality fuel lines. Steve even used the blue fire sleeve that I wanted. They usually use the orange type of sleeve. I think all the lines will fit fine, the only ones still in question are the ones that screw to the fuel pumps since I don’t have those built up yet, but it seems like they will all work. I’ll come up with a more detailed install of the fuel lines when I actually do the install.

The new EGT sensors have an adapter that screws into the M8 thread and then the sensor bolt screws onto the adapter. I used some high temperature anti-seize (copper color) on the threads so that they don’t rust up and are hard to remove. I don’t know what the torquing on these should be so I just got them reasonably tight.

The new EGT has a much shorter lead so it will be easier to replace it if I have to. These are made by MicroFlight (Micro-1000)

The EGT has a 90 degree bend and I didn’t want to take the bend out. Think this will still work fine running the wire up between the cylinder heads.

A short of the fuel lines running between the firewall and the gascolator and fuel pump location. These will need to be torqued and secured.

All the fuel lines in and out of the FT-60 seem to work as well. I need to make a proper bracket for the FT-60.

A few photos of the -4AN line running from the tee (connected to the fuel regulator) into the fuel flow sensor. You can also see (in the upper photo) the short connector hose that feeds the tee from from the fuel regulator.

The -6AN return run has a special banjo fitting that Steve made. You can’t buy a stainless steel 10mm Banjo to -6AN fitting anywhere, you can get aluminum one, but not stainless steel. I’ll need to get a photo of it when I do the install of the fuel lines.

Sensor Wiring

Time: 4.25hrs

Over the past few days I finished up most of the engine sensor wiring. I still need to wire up the oil pressure sender and redo the EGT sensors. On the oil pressure sensor I decided to use my own Tefzel wire instead of using the cable provided by Rotax. I found the Delphi GT-150 connector on Ebay and it looks like it will be an exact fit. I had purchased some other 3 way Delphi GT150 connectors but it seems the pins are slightly in a different place so it doesn’t connect well to the sensor. Will provide photos when I wire it up.

For the EGT sensors I had originally purchased some Aviasport IM-927 K Type sensors which seem like they will work, but I was thinking that they may be a bit hard to service if I wire them directly into the GEA24. These sensors have 6 foot wire attached to the sensor which I was going to put pins on and connect directly to the GEA24, but if I ever need to remove them I’d have to depin the connector and pull the cable out through the firewall, etc. Also since the sensor screws right into the M8 thread on the exhaust you have to turn the whole thing including the wire which makes it even more difficult to change out. I contacted Aviasport and they said that you can extend the leads using K Type wire, but you can’t cut them. So to avoid having a loop of extra wire from the each sensor I order some Micro-1000 EGT sensors that seem like they have a much shorter lead. I can then run the K Type wire from the GEA24 out to the connector near the sensor. I’m hoping this will be a much cleaner install.

Another thing to note is that I changed back to using a single 22AWG shielded wire for each of the temperature sensors. I saw on some RV-12 build pages that they just use a single wire and not a 2 wire connection where one wire goes to the sensor and another to engine ground. The sensors themselves are grounded to the engine block (some temperature sensors have a separate ground wire which would require a 2-22AWG wire) so running an extra ground wire out from the GEA24 seems redundant and not necessary. The GEA24 ground and engine block will be tied together anyways so the only reason you’d run separate grounds would be to just be sure that you have a good ground at the same potential as the sensor ground. I suppose it would be no hurt in doing this, but you could potentially cause some ground loops. even if you wanted to ground those GEA24 pins to the block you could run one ground and jumper it to each of the pins. So it seems to me that you just don’t need to use those ground pins on the GEA24 when using these types of sensors. Now I could be completely wrong on this, but from the RV-12 builds I’ve seen it seems that you don’t need the extra wiring and if I am wrong I just need to run one wire from the GEA24 to the engine block.

I found some plastic covers that I cut one side off to use as a cover for the temperature sensor connections. It’s a little nicer than the bare metal of the FAST-ON connector.

Also put on a little conducive grease to help keep the connection corrosion free.

Finished connector. The other idea was to find a small boot that could slip over the top of the sensor and connector.

Bracket installed and hoses run to the fuel pressure and manifold pressure sensors. I still need to wire tie the hoses and sensor wires. I used 4mm silicone hoses and found some Hitachi clamps on Amazon that look like the Rotax hose clamps. Still waiting on the M6 hose barb for the fuel pressure sensor so that I can connect it to the airbox.

I used Delphi GT-150 3 way connectors for the fuel flow, fuel pressure and manifold pressure sensors. Rotax uses a 3 way Delphi connector on the oil pressure sensor, but it’s a little different pin arrangement (2 on top, one on bottom (like a triangle, not straight like these). There are a few other sensors (like the Kavlico) that use the Delphi connector. Also I found there seems to even be a variation on these 3 way triangle type connectors as well. Will detail more on that when I wire up the oil pressure sensor.


Sensor Bracket and Hose Mock Up

Time: 2 hrs

As I mentioned in a previous post I’ve been working with Steve at Aircraft Speciality to come up with kit for the 914. Today I mocked up some of the hoses to get an idea of the hose length that is needed. Most of the hoses don’t need too exact of a measurement. Only the short hose between the pressure regulator and -4AN Tee (which feeds the sensors and right carb) is somewhat critical.

Also in needing to get a fairly exact hose length measurement I made up a bracket to mount the fuel pressure sensor (UMA N1EU07D) and the manifold pressure sensor (UMA N1EU70A) (which should be here on Monday). In reading the Air Master Installation docs for the propeller they say that a manifold pressure sensor is not needed when installing a constant speed prop on a Rotax (or Jabiru I believe). This goes against what the FAA FAR states, that you need a manifold pressure gauge on any aircraft with a constant speed propeller. Air Master also says that it may be required in Europe and is a good thing to have. I think it’s a good thing to have so I’ll install one. The fuel pressure sensor on the other hand is required and needs to be connected to both the fuel system and the airbox to calculate the pressure difference.

Made a bracket out of anodized aluminum that will hold both the fuel and manifold pressure sensors.

Mocked up some of the -4AN hoses that are needed to connect the various fuel sensors. Also in the photo is the fuel flow sensor (FT-60). I need to make a proper bracket out of .09″ (11 gauge) aluminum. There is a short hose that connects the fuel regulator to the -4AN tee. It uses 2 90 degree fittings (one of which I had to steal to mock up another hose).

Fuel line that will feed into the fuel pressure sensor from the bottom. The airbox pressure is feed into the top 90 degree hose barb fitting (waiting on the 6mm hose barb fitting that screws into the airbox).

Engine Sensors and FT-60 Placement

Time: 1.5 hrs

I purchased most of the engine sensors needed for the Rotax 914. The engine comes with a few, but there are also a few that needed to be purchased separate. Here what I ended up purchasing:

VDO 323057 – Airbox Temp, not absolutely necessary but nice to have.

UMA N1EU007D – Fuel Pressure, Reads differential pressure between the fuel and airbox so it has both a wet (fuel) and dry (air) side to the sensor.

Electronics International FT-60 (Red Cube)– Fuel Flow, Inserted between fuel regulator and right carb to measure fuel flow.

UMA N1EU70A – Manifold pressure, Taps off of manifold tube. There is a Kavlico sensor that is viable with the Garmin GEA24 Rotax kit, but it’s very difficult to find from another supplier. The UMA was listed as an alternate to the Kavlico. You could probably use other absolute pressure sensors as well. (Still waiting for this sensor from Aircraft Spruce)

IM-927 EGT TYPE K – Exhaust temperature, As far as I can find I only need to install 2, though you could technically install 4. They typically are mounted on the rear cylinder exhaust (I believe 100mm from the cylinder). These have a nut attached and mount to the exhaust by removing the hex bolt and using the hole that hole so no need to drill a hole for the bayonet. (still waiting for these sensors from Aircraft Spruce)

So now on to the real headache. One of the goals I wanted to meet was to reduce the amount of rubber hoses used in the engine compartment since Rotax mandates (though it is not mandatory for experimental aircraft) to replace all rubber hoses firewall forward every 5 years. With that in mind I wanted to use PTFE (teflon) steel braided hoses for the fuel lines. In my Googling I came across Aircraft Specialty that has a full kit for the 912, but I didn’t see anything for the 914. I emailed Steve a few weeks ago and he was eager to want to put together a kit for the 914 and even help figure out how to plumb up a few of the fuel related sensors. Steve is builder and pilot and is extremely knowledgeable about the Rotax engines. He shipped out some parts for me to try a day or two after I first spoke to him and now that the Rotax mandatory service bulletin issue has been sorted out I wanted to get back to working with Steve to come up with an offering for not only the 914, but also some things that might make the Sling 4 build a bit better.

The FT-60 install was the first area I wanted to see if it could be improved. TAF has you cut and solder copper hose barbs onto the existing hard line between the fuel regulator and the right carb to insert the FT-60 into the fuel line. Steve felt like this could be better done with flexible lines and AN fittings, so he shipped me out some fittings to try. The space between the regulator and carb is maybe 5-7″ of straight fuel line and once you put the 1/4″ NPT to -4AN fittings on the FT-60 it doesn’t leave a lot of space. The FT-60 install instructions also impose a few restrictions: 1) Mount the sensor with the wires point up, 2) Don’t allow the fuel line to drop immediately on the output side of the sensor, and 3) Orient the sensor so fuel flows to the Inlet and out the Outlet (duh). So with that in mind I came up with a few install scenarios that I will run by Steve. I fabricated a quick bracket just to give me an idea of how I might mount the sensor. After the position has been finalized I’ll make up a proper bracket and Steve can build the hoses. BTW the fittings and hoses he sent are really top quality all stainless steel.

There really isn’t a whole lot of space to install the sensor. At the bottom of the photo (cut off) the hose drops down to the carb and only has room for a 90 degree fitting which the manual says you shouldn’t do. Plus mounting the sensor becomes an issue because there’s not a whole lot of places to mount anything.

Scenario 1: I figured I could get some room by turning the sensor 90 degrees to the fuel line run. I liked this arraignments where I could even put the fuel pressure sensor on the same bracket. The fuel regulator is to the right side of the photo, right carb is to the left. There is a tee fitting that Steve provided that would feed the FT-60 with a 90 degree fitting and a straight hose could be used to feed the pressure sensor from the bottom (using a 90 degree fitting on the pressure sensor).

So the issue with this scenario is that I have to move the FT-60 about 1 inch forward to accommodate a 90 degree fitting to feed into the sensor, plus this connecting hose is pretty short. But it may still be a viable solution.

Scenario 2: This arrangement moves the sensor further forward and a bracket could be mounted over the ignition boxes. The tee is removed from the regulator and moved to the input of the sensor. Since the sensor gets moved forward the out to the carb has a longer hose and no immediate drop. The draw back here is the out to the pressure sensor kind of is in a weird place. I suppose the tee could be put back onto the regulator which I’ll have to try.

Scenario 3: This arrangement kind of combines the previous two. By moving the tee to the in of the sensor allows a bit longer hose and flexibility in mounting height between the sensor and the regulator. The out to the pressure sensor is pointing aft which would work well if I mount the pressure sensor on the firewall or on the engine mount. On the output side a 90 degree fitting could be used or even a straight fitting with a bit longer hose run to get a gentle bend to go down into the carb. I’m kind of thinking this may be the arrangement to do, but I will see what Steve thinks.

Scenario 3 using a long hose run on the out and a straight fitting.

Sensor input side with the tee facing aft. The sensor can be mounted a little lower and the hose is a little longer then scenario 1. The run to the pressure sensor would be about 1.5-2 feet so a bit longer then expected but I don’t think it matters too much.

NOTE (1/1/2019): After speaking with Steve he thinks Scenario 3 will be the best solution. I will need to make a more proper mounting bracket and then I can mock up the hoses with some cheaper rubber or vinyl hoses. I then send them back to Steve so he can make the hoses.

Misc Engine Work

Time: 1.5hrs

I didn’t do too much actual work on the plane today. I mainly did some research to understand the different sensors and what is needed. I did make the mount bracket for my fuel pumps, and alodined a few parts. Additionally I tightened down a few bolts of the alternator bracket that I figured wouldn’t need to be removed. I left the bolts on the arm loose since I will have to tighten the belt on the alternator and can’t do that just yet. I also found that my oil thermostat doesn’t have metric threads even though the firewall forward manual calls for 6mm (12mm long) bolts they’re actually 1/4-20 bolts. 6mm and 1/4 are very close and the 6mm bolt threads in a little, but the threading is different. Fortunately I had a few bolts lying around so I was able to find one that fit and now I just have to order them from Bolt Depot.

What I mainly did today was look through the Garmin and Rotax manuals to figure out the sensors that I need to get. The newer Rotax engines are referred to as “Suffix -01” this is because they have a -01 at the end of their model numbers, for example mine is a 914ul2-01. The reasoning was because Rotax made a change to the cylinder heads to make all the parts the same. So with that there are no longer cylinder heat temperature sensors on the bottom of the cylinder heads, rather there are now 2 coolant temperature sensors on the top. This caused some confusion for me since both are shown in the Rotax install manual. Garmin sells a Rotax kit for use with the GEA24, but there are a few things that you pay for that you don’t use on the 914 and you still need to purchase a few other sensors so I’m thinking I may just skip it and get everything separate. I have detailed my findings in the following table.

Sensor Part Number Comments Wiring
Coolant Temperature Rotax 965531 Supplied with engine (Located on cylinder #2&3). Use shielded 2 conductor wire 22AWG cabling terminate with 250 Faston and ring terminal (for ground) onnector
Coolant Pressure KAVLICO P4055-50G-E4A Saw this mentioned in Garmin manual, but not sure if it’s applicable to the 914, may be 912IS only Use 3 wire 22AWG shielded cabling
Oil Temperature Rotax 965531 Supplied with engine (Located on oil pump). Use shielded 2 conductor wire 22AWG cabling terminate with 250 Faston and ring terminal (for ground) connector
Oil Pressure Rotax 456180 Supplied with engine (Located on oil pump). Use supplied cable and connector. Wiring is long enough to reach GEA24
Mechanical Rev Rotax ? Supplied with engine (Located on generator). Use pins  26&11 from TCU along with zener diode, diode, and 300ohm resistor (comes with Garmin kit or source yourself)
Manifold Pressure KAVLICO P4055-30A-E4A or P500-30A-E4A Can’t find this sensor, Also may be available from Dynon. Comes in the Garmin Rotax 912/914 kit. Use 3 wire 22AWG shielded cabling
Airbox Temperature VDO 323057 This is not required, but will try this sensor. Sourced from Amazon and looks like it should fit (1/8 NPT -27 threads). Use shielded 2 conductor wire 22AWG cabling terminate with 250 Faston and ring terminal (for ground) connector
Fuel Flow FT-60 Aircraft Spruce has these (part # 10-01196) Use 3 wire 22AWG shielded cabling
Fuel Pressure UMA N1EU07D Aircraft Spruce has these (part #10-00980) Use 3 wire 22AWG shielded cabling
EGT TYPE K TERMOCOUPLERS Aircraft Spruce has these (part #15-09438). They can be ordered with 6 or 9 foot wires so no need to buy special K type wire. Also should mount to M8 threads in exhaust. Use supplied wire