Two of us early 12 fliers have had sudden psi fluctuations in our fuel pressure on the Dynon. Turns out, in these two cases it was trash on the gascolator screen from hastily cleaned out fuel tanks or not screening fuel before we sent it down the funnel. Yes we were told...by Van's and by friends. But like "get home Itis" there is "fly-your-project Itis". Lots of us use fuel that we pour in from gas cans which compounds the problem of course. So I've learned two things: screen everything (the Spruce funnel?) and clean, clean, clean that tank spic and span before filling. Actually, I've learned three things: the Dynon glass screen alerted me to the problem...the engine never sputtered...but it would have no doubt...thank you Dynon.
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
RV-12 Gascolator
- Thread starter Peterk
- Start date
More info please,
Pete, so was it bits of fuel tank sealant on the screen?
How do you clean out the fuel tank?
Tony
Pete, so was it bits of fuel tank sealant on the screen?
How do you clean out the fuel tank?
Tony
Geico266
Well Known Member
Typically, the screens in the gasolator are only cleaned once a year at CI annual. It maybe be a good idea to clean the screen (spray can brake cleaner works good) at the first oil change of 20 - 25 hours to look for construction debris.
I cleaned my tank by adding a gallon of two of fuel and shaking it for 2-3 mins and letting the fuel drain out of the tank and screen the gas in a MR. Funnel. Repeat 2-3 times. until there is no debris in the funnel.
Good catch Pete.
I cleaned my tank by adding a gallon of two of fuel and shaking it for 2-3 mins and letting the fuel drain out of the tank and screen the gas in a MR. Funnel. Repeat 2-3 times. until there is no debris in the funnel.
Good catch Pete.
Last edited:
Not a bad idea at all, but their can still be debris within the rest of the fuel system (from making the lines, etc.)
This why the production acceptance checklist has a procedure for flushing fuel through the majority of the system and then inspecting/cleaning the gascolator before the first flight.
Just curious, how do you take a fuel sample from the RV-12 tank before each flight? I didn't notice a drain under the fuselage when I saw the RV-12 prototype.
There is a drain check on the bottom of the gascolator under the engine. I really think most of my "junk" was from not pouring my gas can product through a screen first. We'll see how things go now that I do. I think Larry's program is probably the way to go but Scott is right too...you have to clean the line as well.
fuel sample
What tool is everyone using to sample fuel from their gasolator? I noticed this weekend when I tried to sample fuel the bowl is about 2" up under the lower cowling with the only access hole the small opening the overflow tube exits or by reaching in through the rear opening of the lower engine cowling by laying on my back. Am I missing something here?
What tool is everyone using to sample fuel from their gasolator? I noticed this weekend when I tried to sample fuel the bowl is about 2" up under the lower cowling with the only access hole the small opening the overflow tube exits or by reaching in through the rear opening of the lower engine cowling by laying on my back. Am I missing something here?
Tip: Make sure the hole is big enough to take the sample tube before you paint the cowl.
RFSchaller
Well Known Member
I replaced the gascolator drain valve with one that locks open with a twist. I like it for several reasons: it prevents a vacuum lock when you are removing the bowl for insp Cotonou, it makes draining your fuel system easy and I don't need the stem that protrudes above the tester tube. You do have to remember to verify the valve shuts after taking a preflight sample, but that has only happened once in over 100 samples and it was obvious.
Not always obvious.....
There is at least one RV take-off accident caused by the use of a locking drain ion the gascolator.
RV owners usually learn early on that almost no fuel comes out of the gascolator drain unless the electric pump is on.
If someone is unaware of this detail, it is possible to accidentally leave it open with little to no indication, if the electric pump is off.
Once the engine is started the large leak will obviously have a major impact on engine performance.
RFSchaller
Well Known Member
Scott, the one time I inadvertently locked it open while sampling the trickle was pretty obvious, and as I said ensuring it is in the correct position is an important part of my preflight. I've owned a Cherokee 180 with this type of drain valve on each gas tank as well as the gascolator for 31 years, so it is second nature for me to check the valve status after sampling. I think the advantages I mentioned make the twist-to-lock valve a good choice as long as reasonable care is taken. You can't eliminate every possible bad scenario with design without losing some desirable features.
scottmillhouse
Well Known Member
I flushed my system as per instructions when doing the PAP procedures and at 103 hours have had no debris on the screen, bowl or with any fuel samples.
At risk of a thread drift, thought I'd post my recent experience. Just did my first annual and was unable to remove the right rear gascolator screw. There is a nut plate for a clamp inside the airplane that holds the fuel return line as shown on drawing 22-02. I had too much thread showing through the nutplate adjacent to the screw and the extra was just enough to block screw removal. No problem when trimmed flush. In final assembly I probably used too long a screw. This error made a 10 minute inspection take several hours.
At risk of a thread drift, thought I'd post my recent experience. Just did my first annual and was unable to remove the right rear gascolator screw. There is a nut plate for a clamp inside the airplane that holds the fuel return line as shown on drawing 22-02. I had too much thread showing through the nutplate adjacent to the screw and the extra was just enough to block screw removal. No problem when trimmed flush. In final assembly I probably used too long a screw. This error made a 10 minute inspection take several hours.
My comment wasn't really for you Rich.... just mentioning it for others since I can confirm the potential for it causing a problem is real (I saw the wreckage that was the result of the forced landing it caused.
BTW, this was on an early RV-6 where someone had used a cherokee gascolator / fuel pump assy.
RFSchaller
Well Known Member
Scott,
Yep, each builder should definitely consider your position and beware of the issues before they decide what's best for them.
Rich
Yep, each builder should definitely consider your position and beware of the issues before they decide what's best for them.
Rich
