K5054

19 hours ago, cscotthendry said:

I just reread the fc10 manual. It seems like adding a second sensor should be pretty easy.

The cube has 3 wires, 2 are for powering the sensor and the other wire is the signal back to the FC10. The second cube gets its power from the same connections that power the first cube ie, their power connections are paralleled. Then the signal wire for the second cube connects to pin 8 of the FC 10.

But now you have two k factors to adjust. One for the supply sensor and one for the return sensor. The K factor is like a “slippage” or fudge factor for the sensor. 
Since you say you get accurate numbers by turning the return off, I'd guess you have the K factor about right for the supply sensor. If you mount a second return sensor near the first one and in a similar orientation, you could use the same K factor for the second sensor as a starting point.

By leaving the number of engines set at 1 in the FC 10 setup, I'm guessing that it will subtract the second sensor's readings (adjusted by its K factor) from the first sensor's readings.

HTH

The fuel pressure is at the higher end when return line is closed but gets close to limit when boost pump is on. With return line open it sits about 3-4 and 5-6 with boost pump on

7 hours ago, cscotthendry said:

Good stuff.

I still think your return quantities bears investigating. From the figures you quoted, it sounds like more fuel is bypassing the carbies than they're consuming and that doesn't sound like it should to me. I'd check that the restricter is there, that it is the correct size, and is in the correct path.

BTW, the local Rotax dealers suggest a carby jet insert as the restricter. From memory, it is an M5 thread and will fit nicely in the end of a brass T that has been threaded with an M5 tap. Rotax sell a cross connector with the built in restricter, but it's very expensive!

Good luck.

5 hours ago, Thruster88 said:

The fuel pressure produced by an engine driven diagram pump is done by the internal spring, it cannot be to high if it is the correct pump. Are you sure of the accuracy of your instrumentation? 

The engine is 2018 so the pump is new and correct. The fuel pressure gauge is and old one direct reading though. Can’t really tell how accurate it is. It takes its pressure from Y fitting just before the 1/3 carb

I tried a number of different size restrictors in return line starting with the recommended size but that back pressure pushed the fuel pressure too high, so I started increasing size incrementally until it was within limits. This ended up being quite a large bypass hole. Recommended factory return line restriction is 0.35mm

mine is 1.5mm in order to keep fuel pressure  in limits which is over four times the normal. On the up side, there is less chance of getting a blockage 🤔

Actually I had a read again and I think you are right. I have to add another pin to the gauge plug. 
I was wondering if I just pigtail the power from the existing wires and you think I do 👍

I also am guessing that leaving it as single engine makes it subtract 👍

it means I can save a lot as a second cube is only about $250

I will try it out. I’ll let everyone know how it goes. 
thanks for the help 👍👍

Mine is very accurate if I close return line off. It’s the fuel flow when return is open that it cant cope with. I would get a second transducer if I knew how to wire it into my gauge as it says you can (pin 8 but it’s not clear how to.

it would be a lot cheaper to just get another transducer 

The k factor can’t go low enough to cater for the return. 

I think I will sell it and install this

https://www.scintex.com.au/products/engine-fuel-consumption-gauge-supply-return?_pos=30&_sid=a33b01d08&_ss=r

I did try a few locations in the engine bay but now it is on the floor below the tank in cool non vibration area with straight hose before and after on cabin side of firewall. It’s a 912ULS. I could try a different return orifice which would bring fuel pressure higher but still in limits. 
If I adjust k factor for cruise rpm, wouldn’t that change with altitude as power drops off making the readings only accurate for where I set it at low altitude? 

Thanks I appreciate your response. I’ve tried that technique before though over a year or two. I tried various k factors to accommodate the return line but the fuel flow varied too much throughout the rev range. At the moment my fuel flow is say 20lph but total with return line is 53lph. This is with the return line orifice that gives the correct fuel pressure. I have also tried putting the transducer on one carb and doubling amount. Again, not accurate. I’m not sure what else to try. At the moment I can get accurate reading by manually shutting return off in flight.

Does anyone have a diagram on how to wire a second “red cube” onto the FC-10 meter for the return line on a rotax. The instructions are too vague

Hi,

can anyone tell me if I am allowed to hire out my aircraft to someone for private hire as in they can use my aircraft but pay me an hourly rate for its use? (VH rego)

The wing bug software only allows setting altimeter in inches. I have written to them and he said he should be able to put hectopscals in and will let me know. You should send a similar email as they are cutting themselves out of the austrAlain market and the more enquiring about it, the quicker they will fix it. I have a similar problem. Can’t put mounted instruments in without big expense (VH rego) and really old instrumentation. So I’m currently looking at the wing bug. BOM is the alternative. I think they are both great product. Wingbug a bit cheaper and doesn’t self charge but I would take it home to charge anyway. 10 hours battery is pretty good. but they seem to do the same things. Both have A of A by the way. I do like the wingbug six pack presentation and as I have a portable ADSB in device, I don’t require it.

I have single seat which I love as I enjoy the solitude of flying. It is rare I need to take a pax but I have a share in a two seater I can use if needed.

Mine in my savannah used to do the same on a hot day. If CHT/water temps are ok (as well as oil temps) it should be fine. Detonation is the main concern but it is to a lesser extent on water cooled heads. Use as high an octane as you can (98) to help against detonation and monitor engine temps.

I would suggest that it would depend on what sort of aircraft it is. LSA require manufacturers approval for the smallest mods, If you're 19 rego, then it could be an owner modification.

That said, it's only likely anyone would find out if things go pear shaped and the level of risk would need to be assessed.

Thanks. Yes I’m 19 rego owner/builder.

Howdy, Can anyone Help me with this question?

my VHF is in shop being repaired. I have an Icom portable that works well connected to my headsets and transmitting through the Aircraft external Antenna. Battery lasts over Six hours.

is it permissible for me to use this set up in the interim while my built in is repaired? I can’t find any Raaus reference. Aircraft is Raaus rego.

yes I will be flying in class D airspace.

I had my exhausts coated in the highest heat resistance. I did it to keep heat down under cowl. It didn’t make a scrap of difference and I have had to wrap them again. If you are going for looks it’s good and will preserve the pipes but don’t bother if you are primarily going for heat reduction

My sender is in the line between the Facet pump and the mechanical pump (which is the longest straight line), with the return line after the mechancial pump. It is important that the return line fitting is after the mechanical pump (I think most engines have it in the 4-way joiner from the pump to the 2 carburetors). I haven't seen any installation where the sender is on the mechanical pump outlet?

How do you account for the returned fuel which would be included in the fuel flow?

I’m relocating a fuel flow (red cube) sender in my rotax. I think the current set up is too close to the fuel pump on rotax 912ULS and pulses are giving erroneous readings. So I’m lengthening the fuel hose so it has 6 inches of straight hose before and after it (as recommended)

My return line has to be upstream of transducer (so I don’t have to buy two) but I’m wondering how far upstream is allowable.

Not sure if by having a long length of hose between the return tee and the transducer would defeat the purpose of the return line and allow vapour lock as there would be a fair distance of hose to be heated. (maybe 1200mm)

It will all be fire sleeved

Ok. Might have to put smaller oil cooler in. That will bring temps back down I think

No wires are the same. With the bigger oil cooler the radiator has less area/airflow than it did

Hello all,

I have recently changed my oil cooler in new (150hours) rotax 912ULS as the temps were slightly high. Oil temps are now good but the CHT’s are higher than before (expected) due to positioning.

my engine has the newer CHT limit of 120°

my question is are these temps ok. Or should I be concerned and try to lower them?

(°C)

OAT    CHT.     OIL

17°        94°      88° (Cruise)

22°      100°     90° (high speed cruise)

20°      110°    105° (extended climb)

my CHT temps used to be 70-90°

Need more details.

landing on grass?

carrying too much speed on touchdown?

where was touchdown?

did they fade or fail?

how long is runway?

what is pilot skill level?

is there grass on side of flightstip?

Landing weight?

headwind/tailwind.

braked and non braked performance?

etc etc

with all the variables you have to make the call at the time.

Empty is about 420kg. Will be something like that. I haven’t got all the details yet

Yes it might lose 6 kts at 600kg. Not sure how to drop that much weight though, unless it’s simply restricted to that.