[drill_and_buck]

O360 and Vans FWF kit

I am installing a TMX O360 CS on my RV-8 and using Vans FWF kit. I was connecting the fuel system this evening and was disappointed to find out that I could not make the connection between the gascolator and the engine driven fuel pump.

The plans call for installing KBO45 fitting, which is a 45 degree fitting, on the right side of the fuel pump. The problem is that you can not screw in the 45 degree fitting. It hits the case where the prop governor gets installed.

My plans are to return the fitting and the VA-129 fuel line and use a straight fitting and order a fuel line with a 45 degree end. I have to believe that there are a lot of other O360s being installed. I am not sure why Vans includes these in the kit if people end up returning them. If you are planning to install a O360 CS, save yourself the aggravation and delete the above two items from your FWF kit.

Anyone else install a O360 CS and run into this? If so, what was your solution?

-Mke
RV-8
Finish

 

[Davepar]

Unfortunately, a common problem. I installed a 90 degree fitting in the pump. The fuel line from the firewall to the engine driven pump (fuel injection--no gascolator) then ended up being too long. I'm paying $50 to get it cut down. Actually more than that because one of the ends was screwed up by Vans (or whoever makes their hoses) and couldn't be re-used.

Using a 90 degree fitting in the pump will probably be cheaper than a 90 degree hose end. Those things are expensive.

Dave

 

[mburch]

Hope I'm not hijacking the thread too bad, but I swear it's germane to the discussion of firewall forward issues with the TMX IO-360.

Dave - How did you end up making out with your throttle quadrant? Is it worth it in the end? I just ordered my engine (same basic M1B setup as yours) and I'm wondering which way to go.

thanks,
mcb

 

[drill_and_buck]

Dave:

Great idea.

Glad to hear that the 90 degree fitting fits. Yes, that is a lot less expensive than a 45 or 90 degree hose fitting.

Thanks!

-Mike

 

[Davepar]

Don't ask me if it's worth it yet. So far I've only been able to make airplane sounds with it. Maybe once I'm flying it'll seem worth it. Of course, I'd probably be flying by now if I skipped it.

It is working well now. One of the levers is a bit stiff, but that's only because one of the dust boots is a bit tight. With some lube on there, it works well and will hopefully break in over time.

The additional complications with the throttle quadrant that I found:

1. Custom cables required. If needed, I can provide the lengths I used. The cables from Vans are the only ones I found that will work with their engine mount points, unless you want to spend hundreds at Spruce and wait a few months. The primary drawback to the Vans cables are that they are too fat to work with the non-aluminum firewall eyeballs. Also, the Vans custom cables say "not for use in aircraft." Comforting. They try to cover this up with their part number tag, but the wording was still visible on one of mine.

2. Difficult cable angle. The quadrant wants the cables to enter at about 2:00 looking from the side. However, the cables actually enter at 3:00. The cables have a swivel end, but not enough to make up the difference. You have to kind of mount the cables high and angle them in. Also, altered or special clevis ends (see Bill Repucci's site) are needed. Standard clevis ends will hit the lever arm.

3. Throw adjustment. With knobs, you don't need to worry too much about throw. As long as the mixture/throttle/prop arm moves from stop to stop, you're good. With the quadrant, it looks kind of goofy if the levers don't all hit the bottom or top of the arc. This involves drilling new holes in the lever arms to tweak the throw.

4. Lever arms close together. Even if you don't care about the lever arm throw, the clevis pins will interfere with each other using the stock mount location in the arms. The arms are just too close together.

5. Bulkhead mount point. Mounting the quadrant was fairly simple, but figuring out how to make a bulkhead for the cable bulkhead nuts was tricky. In retrospect, I wish I would have spaced them further apart.

Ok. Now we've really hijacked this thread.

 

[frankh]

Back to UN hijacking...

Remember your local hydraulics shoppe!

I had them shorten an Aeroquip hose by lopping off the end, shortening the firesleeve and crimping a new fitting on the end which they keep in stock.

Total cost about $8 I think.

They can also make new hoses but they probably won't have any firesleeve...WAAY cheaper than so called proper airplane hoses and they look exactly the same and have the same or better temp/pressure ratings.


Very useful place and they love a challenge.

Frank

 

[mahlon_r]

Could you remove the prop gov drive assembly, from the accessory housing and install the fuel pump fitting in the fuel pump and then reinstall the prop gov drive on the engine?
There is nothing different there, as compared to an engine from Lycoming, so I would think the problem is universal to any 360 engine with a prop gov drive on it, regardless of the source.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

 

[rgbewley]

90 Degree Fitting on Fuel Pump

Be careful about putting a 90 degree fitting on your fuel pump. The fuel will aspirate on the sharp 90 degree curve and could result in insufficient fuel flow. Better to put in a straight fitting with a sweep, although more expensive (probably about $40.)

 

[Captain Avgas]

No redundancy

Remember your local hydraulics shoppe!
They can also make new hoses but they probably won't have any firesleeve...WAAY cheaper than so called proper airplane hoses and they look exactly the same and have the same or better temp/pressure ratings.
Frank

The problem is they "look" the same...but they're probably not. You're most likely getting hose fittings produced in China without any QA control.

There's absolutely no redundancy on fuel lines FWF. One strike and you're out. It's one of the places on the plane where aviation quality components are a very good investment.

And coming down suddenly might not be the worst scenario....there's always the prospect of a fuel fed fire to contemplate.

Incidentally, many builders believe that swaged end fittings are the best. However this is a misconception....Aviaquip reuseable hose fittings are in fact more reliable than swaged fittings.

In short, it's the Experimental Category.... but I wouldn't be too experimental with fuel lines.

 

[Davepar]

I know next to nothing about fuel hoses, so went conservative with a reputable local aviation shop for the modifications.

That's an interesting point about the 90 degree fittings before the pump. I think you mean vaporize, not aspirate. However, there are at least a few other 90 fittings in the fuel line before the pump on the standard setup from Van's, although all aft of the firewall. I could wrap it in firesleeve as added insurance.

 

[rgbewley]

Although vaporization can occur, I really did mean aspiration -- drawing air in or through the fuel principally by suction. When the fuel hits the 90 degree turn, it slows down. The fuel pump is still trying to pull fuel in at the same rate, creating a void for air to enter the fuel flow, resulting in a drop in fuel pressure and possible engine sputter/stoppage due to lack of fuel.

 

[drill_and_buck]

Thanks Rhonda. I had a nagging feel about 90 degree fittings in fuel lines but I couldn't recall the particualr issues.

Sounds like this might be the weekend to remove the pro gov drive assembly and go with the 45 degree fitting.

To Mahlon's point if every Lycoming case has the same profile then Van's should give people a heads up that you will need to remove the prop gov drive assembly or they just provide you with a fuel line with a 45 degree fitting. They already ship a straight fitting in the FWF kit.

They ship you a 45 and a straight fitting for the fuel pump. You only need one, go figure.

Thanks everyone for the feedback. It has been very helpful.

FWIW, I sent a question to Van's support the same time I posted the question here. I am still waiting on a response.

Mike
RV-8
Finish

 

[Davepar]

Although vaporization can occur, I really did mean aspiration -- drawing air in or through the fuel principally by suction.

Where is this air coming from?

I counted in my plane which is Van's standard fuel injection set-up. Between the tank and the mechanical fuel pump, there are two 90 degree AN fittings (3 for inverted fuel pick-up) and 2 right angle turns through T's. Why is the fitting going into the fuel pump any different than all those right angles?

Here's a pic of the hose from the firewall to the pump in my setup.

 

[rgbewley]

There is a certain amount of air dissolved in any liquid, the amount depends on the pressure. If a restriction to flow is present in the line and a reduction in pressure (suction) is applied to increase the flow rate, some of the dissolved air will come out of solution because the pressure will decrease in the line. The same situation as popping the cork on a champaigne bottle.

Vaporization, as you know, is when a liquid is heated to its boiling point. In operating conditions, both events occur given the opportunity. As totally eliminating the heat source is not practical it is better to have as few
restrictions as practical. Sharp cornered 90 degree fittings introduce a restriction and when the suction is high enough for the required liquid flow to approach the limits of what the supply line can flow the liquid will aspirate, forming small pockets of no fuel.

To detect this proplem, turn the boost pump on while the event is occurring and see if the problem goes away. If the normal pump output pressure is returned there is aspiration and/or vaporization taking place in the supply line. A -6 unmetered fuel line has plenty of flow capacity but the capacity decreases with each turn, reduction in diameter of the line when compared to a straight, constant cross section line. Aspiration is not likely to occur except at high flow rates.

Some installations require a sharp 90 deg. fitting but they should be kept to a minimum. The discharge side of the pump is at a higher pressure and therefore will not as readily aspirate. But, if air is present in the line the pump will pass the bolus of air thru but reduce its volume.