R

ron sterba

Well Known Member
Rv9A. IO-320 Everything is wired and complete firewall forward. Have Andair electric pump and filter installed just below Andair selector valve. My ONLY place to drain fuel from the fuel system is under the tanks. I'm so use to draining the C-172 tanks and carb drain that I was wondering should I install the fuel/filter drain or a gascolator (2013-14 Page 12 Vans catalog) on the firewall? Again my engine is injected. Seems it would be awkward to clean a filter thats in the cockpit or does it even matter?

Ron in Oregon
 
Ron,

I'm putting a similar set up in an RV-6 I'm building. IO-320 and Andair pump/filter. My research indicates that no gascolator or filter forward of the firewall is best. Heat soak of the fuel is a problem, and injected engines don't have a float bowl to fill up with water like a carburetor. The water just goes through the injectors. I am however planning on pre-filters in the wing roots. Andair makes a nice one (GAS375) that can be drained. They would act as a pre-filter before the fuel pump.

spark68
 
please someone explain the difference between a big slug of water in the bottom of a float bowl or a big slug in the bottom of a fuel tank.thanks
 
ron sterba said:
Rv9A. IO-320 Everything is wired and complete firewall forward. Have Andair electric pump and filter installed just below Andair selector valve. My ONLY place to drain fuel from the fuel system is under the tanks. I'm so use to draining the C-172 tanks and carb drain that I was wondering should I install the fuel/filter drain or a gascolator (2013-14 Page 12 Vans catalog) on the firewall? Again my engine is injected. Seems it would be awkward to clean a filter thats in the cockpit or does it even matter?

Ron in Oregon
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bobnoffs said:
please someone explain the difference between a big slug of water in the bottom of a float bowl or a big slug in the bottom of a fuel tank.thanks
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Ron has drains on the tanks but his injected engine has no float bowl.
 
I think that is the point being made. The lowest point in the system is the fuel tank drain. No need for other sumps. Cessna and other similar have more than one low points in the system and need drains at each low point.
 
spark68 said:
Ron,

. Heat soak of the fuel is a problem, and injected engines don't have a float bowl to fill up with water like a carburetor. The water just goes through the injectors.
spark68
Click to expand...

Not quite true. Enough water will stop the engine. We totaled a fuel injected Cessna Agwagon as a result of water-contaminated fuel....yeah, water will go through the injectors but then combustion ceases, no?

Best,
 
Gascolator/drain

If you choose a gascolator (I have one on my-4) and it stays stone cold even between the pipes, make sure it has an accessable drain, and use it. We witnessed a nearly disasterous Lancair deadstick landing that totaled the aircraft because it was built with a gascolator that had no access with cowl installed. There was 8 oz of water in it when we pulled it apart, although he had just sumped wings,and done full run-up, and even flown the day before. The engine quit during climb out/departure turn.
 
The reason you get water 99% of the time is condensation. It's why you fill the tanks if the airplane is sitting, to minimize that void and reduce ability for condensation to collect. A fuel injected system has no void beyond the tanks for air/moisture to collect so no I would not, and don't have a gascolator.

If somehow a small amount of water is able to collect in the lines, you would have pulled it through the engine between start up, taxi, run up. Water in the tanks is the threat.

As far as the gascolator above the exhaust pipes, I would be more worried about it developing a leak right onto the hot exhaust. Drains have little rubber o-rings that can wear, fold over, or get debris stuck under them preventing a good seal.
 
spark68 said:
Ron,

I'm putting a similar set up in an RV-6 I'm building. IO-320 and Andair pump/filter. My research indicates that no gascolator or filter forward of the firewall is best. Heat soak of the fuel is a problem, and injected engines don't have a float bowl to fill up with water like a carburetor. The water just goes through the injectors. I am however planning on pre-filters in the wing roots. Andair makes a nice one (GAS375) that can be drained. They would act as a pre-filter before the fuel pump.

spark68
Click to expand...

At least one fuel injection manufacturer requires a fuel filter either immediately before or after the mechanical fuel pump. That could be FWF on a RV.

Bevan
 
Low Point Drain

Bevan said:
At least one fuel injection manufacturer requires a fuel filter either immediately before or after the mechanical fuel pump. That could be FWF on a RV.

During the pre-cover inspection of my RV9A, my MDRA inspector brought up the following issue with my fuel system:
All went well with the exception of the lack of a drain on the section
of fuel line that runs between the High Pressure Boost pump (fuel
injection style) and the gascolator on the firewall. This section of
line runs parallel with the brake lines on the cabin floor. The
inspector pointed out that this section of line represents the lowest
point in the fuel system and could accumulate water. He felt that I
should elevate the fuel line to the same elevation as the discharge of
the Boost Pump (Fuel Injection Boost Pump, not facet style) and run
this line at this elevation to the cabin side of the gascolator,
therefore making the gascolator the low point drain,
OR
Install a "TEE" fitting with ?" branch on the section of line in
question and use this branch with a quick drain fitting as my low
point drain.
I sent this info off to Vans support and received the following response:
We regard the tank drains as the low point in the system. So far as we know, it hasn't been necessary under any licensing authority to add more drains, or raise the fuel lines in the fuselage. I'm sure there are plenty of RV- 9As flying in Canada without any mods like that, and I would be cautious about modifying a proven system which has worked well in practice.
Vans

I have added a gascolator as it is required in Canada. I have added a drain fitting to the gascolator and can drain it without removing the cowling.
I am wondering how this will pan out during my upcoming final inspection next month.
Cam Andres C-FTLL
RV9A with IO360
Almost there..
Click to expand...
 
GENTLEMAN! I Am ahhh-ed at the educational line of thinking. Each time a post came up it opened a avenue of either or possibilities of events! I couldn't have posted a thought because each one held its own validity. I can only say that by the time these posts conclude it should be archived in VANSAIRFORCE library. I look at HOW you installed a system and then articulate the WHY! You builders are amazing! In a day or two I will post again as I enjoy the comradery. Thanks so much for the thought process to help me make the right decision. I'll print these posts for a folder for ALL ITS OWN. These are as I see it a MUST HAVE for for any builder of any plane.

Much appreciated guys! Gals too!

Ron in Oregon
N421HJ RV9A
 
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Cam

I completely disagree with adding the Tee and/or raising the fuel line. Water could accumulate in a fuel tank where there is a large volume of stagnant fuel and/or air (condensation). However, I do not see how water will accumulate in a fuel line where the fuel is usually flowing and contains no air. Especially for such a short section of fuel line as this. If this was the case, you would need a tee for "each" section of "low" fuel line. It just isn't going to happen. It's going to get pumped through the line quicker than it can accumulate.

I slug of water may get picked up from the tank (assuming it wasn't completely sumped prior to engine start) and pumped through the lines. Some of that water may get trapped in the gascolator. But it also might just get pumped through. Are you using a fuel return type system or purge valve?

Let us know how your final inspection goes. I'm not too far behind you.

Bevan
 
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Lower point

My MD-RA inspector juste leave my shop half an hour ago and tell me the same thing than Tailcreek_flyer. We want a drain valve between the fuel selector valve and the boost pump (I will have a carb engine). It's not very complexe to put a valve here, but all thing added are something more who can fail... I will have the gascolator with a drain on it. Tailcreek_flyer, please report us the result of your final inspection !
 
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