Quiz - What's wrong with this Gascolator installation?

I stumbled across this during a condition inspection, can you spot the problem with this install? (Ignore the wires, thats not the issue here).

The letter 'T'

I've never built an RV.....yet but as a former jet engine mechanic I'd say that is a major risk for chaffing against the firewall.

Teflon Tape!

Doesnt that unit feed from the back??? Note arrow directions in image below.

The first things that catch my eye is that the fire sleeve on the inlet side has no clamps. One end has a tywrap, but that might as well not be there unless it's fireproof. None of the fire sleeve ends are "sealed". Teflon tape on the pipe threads.

That was quick and Mike wins a beer at Osh!
This picture makes it a little clearer whats going on... the feed is from the back like Mike indicated, this was just acting large pass through heat sink, with no filtering.
The worst part is this was on a very old RV6 with sloshed tanks and this was the only filter except for the carb inlet where I found debris, been overlooked for probably 20+ years
(true teflon tape is also a good find and missing firesleeve clamps)

Sorry I couldn't make out the arrows in the picture.

Thanks Walt, I bought one of those units thinking it was dual input, single output--------was going to use it on a high wing project.

You dirty coppa

Copper line on the top. (for a primer?) ....Can work harden

I took a shot. I'll um.....be back in the corner reading if ya need me.

IN and OUT on the primer solenoid are reversed from recommended directions.

Copper Tubing

Copper tubing was used extensively by light aircraft manufacturers well into the 50's maybe later. Perhaps most commonly found on Pipers. Nearly all the Piper hoses, lines fittings etc in the 40's and 50's was non aircraft.

the solution???

...so, if all my primer lines are copper, what's the better practice?
Is aluminum better somehow?

seems other hi-temp materials are already 'hard', stainless, steel....so should they be tiny firesleeved flex lines?

inquiring minds need to know!

Walt said:

That was quick and Mike wins a beer at Osh!
This picture makes it a little clearer whats going on... the feed is from the back like Mike indicated, this was just acting large pass through heat sink, with no filtering.
The worst part is this was on a very old RV6 with sloshed tanks and this was the only filter except for the carb inlet where I found debris, been overlooked for probably 20+ years
(true teflon tape is also a good find and missing firesleeve clamps)

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Either the airplane isn't actually 20 years old or the fuel system has been upgraded, because that version of the gascolator has only be availabe for about 10 years or so.
Regardless, I guess who ever installed it was totally blind to the arrows.

jrs14855 said:

Copper tubing was used extensively by light aircraft manufacturers well into the 50's maybe later. Perhaps most commonly found on Pipers. Nearly all the Piper hoses, lines fittings etc in the 40's and 50's was non aircraft.

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Actually Piper was still using it at least into the early 80's on there primer systems.
Installed correctly, it is a valid method, though it seems to always require more than its share of repairs/maint.

Is that Teflon tape on the connections?

I was about to make a snide comment, but then I realized I learned a thing or two (or three ) on this thread.

Note to self: hold the snide comments until you have been turning wrenches on airplanes more than a couple years, noob!

Gascolator

The fix would be to install a decent filter and eliminate the un-necessary gascolator. On the trail dragging RV-6 the low point in the fuel system is the tank drains, so a gascolator mounted anywhere on the firewall is up-hill from the low point and only serves as a poor filter and a heat sink for vapor lock.

There is a lot of grandfather worship in what some builders do. Certified Grumman aircraft, like the AA1-A Yankee I owned for 23 years, do not have gascolators for the same reason. The low point in the fuel system is the tank drains.

Danny King said:

The low point in the fuel system is the tank drains.

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On an RV-7 or 9 with a fuel system built per plans the system low spot is the line running between the fuel selector valve and the gascolator (on airplanes with carbed engines).
Gascolators were never specifically designed to only be installed at system low points (though they are sometimes installed that way). By design, they induce an artificial low point in the system. The tank drains are the best first line of defense for removing water and contaminants but it is not a guarantee because water and contaminants can get trapped in outer bays of the fuel tank and only makes its way to the area of the tank drains in flight. It is for that reason it is a good idea to have something downstream in the fuel system to capture water, etc.

Good point Scott, I knew I installed the gascolator for some reason. Thanks.

Jim Fogarty
RV-9A Flying

jrs14855 said:

Copper tubing was used extensively by light aircraft manufacturers well into the 50's maybe later. Perhaps most commonly found on Pipers. Nearly all the Piper hoses, lines fittings etc in the 40's and 50's was non aircraft.

Click to expand...

True dat! With respect to the fuel line plumbing on my 1950 PA-20, the local auto parts store has become my best resource! I have always wondered if someday I should change it over to AN fittings? But, then again it has been working for 65 years!
All the primer lines are indeed copper, and I have only had one broken line in the 12 years that I have owned the plane. This is likely due to the fact that all the lines are very well secured to prevent vibration.

Danny King said:

There is a lot of grandfather worship in what some builders do.

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That's not exclusive to homebuilts--give the systems parts of the certification standards a good read sometime.

I think what happens is that someone comes up with a good/simple/effective way of doing something on an airplane, that's better than other ways that are feasible within the limitations and assumptions valid at that time.

Over time, especially if the pertinent technology is relatively stagnant, that way of doing things becomes the de facto industry standard, maybe even becoming part of the certification standards. If the underlying assumptions don't change for a while, people and industry gradually forget the reasons why it became the standard in the first place--"this is the best way to do it right now" becomes "this is the best way to do it", which in turn becomes "this is how it will always be done".

That's all well and good so long as the assumptions and conditions continue to hold true. But when something comes along that changes or invalidates those underlying assumptions--whether it's new knowledge/understanding, or a new/better technology, or something else--you have a problem. Sometimes it's a regulatory issue--a really simple example is 23.1557, which requires all "reciprocating engine-powered airplanes" to have their fuel filler openings marked with the word "Avgas" and minimum grade, which was great when all piston airplanes burned avgas exclusively. But these days, not all piston-engine airplanes do--if my airplane has a diesel engine and therefore runs on diesel/Jet-A, I've got a problem, albeit one that is relatively easy to get around.*

Now that's a simple example, but when you start looking at more complex things related to avionics, or to engine control, the waters quickly get muddier and hotter. In the interest of civility I'm not going to get into specifics, but I'm sure all of us here can think of cases where an older, established practice has been put up against a newer one. I'm not saying that the new practice/method/technology must necessarily be better--I just ask that, before immediately falling back to the older "proven" practice by default, take a moment to ask yourself a couple of questions: Why did this method become the standard? What made it better than the other ways? What things were taken for granted or assumed then that aren't now? What has changed between then and now? and If I didn't know about this older way, and was trying to start from scratch today, how would I do it? Do some research if you have to. If you really sit and think about it, and answer yourself honestly, you might change your mind. Or, maybe you won't. Either way, you've learned something And now, you're making an informed choice rather than blindly adhering to the past or slavishly following the latest trend.




* I bring this example up because it's one of the many things we've run into in the ASTM groups looking at the new Part 23 standards. It was relatively easy to fix, but we've run into a whole bunch of situations where the question to the FAA participants of "well, why is that the rule? It doesn't make sense/is outdated/is based on assumptions that aren't valid any more" is met with answers like "well, when we wrote the rule 40 years ago nobody imagined there would be another way to do it" or "well, we don't really know why it's the rule, but we're sticking to it". Nobody has been able to explain to any degree at all why position light lenses need to be "flameproof" but landing lights need only "not present a fire hazard", but they won't consider changing it, either.

Multiple issues that have all been identified above but I would add the fact that it has one at all.

Oops, I just noticed Danny had already made this point.

I think the main point I'd like to see folks take away from this is that every time you do an inspection, especially if you're looking at your own aircraft, is that you really need to take a step back and try to look at things with a "fresh set of eyeballs".

This aircraft was built in 1992 and I have no idea when this part was actually installed, but I can assure you it wasn't recently so it has been overlooked for quite some time.

This is an excellent example of how having someone else do your condition inspections every now and then can be a good thing, owners/inspectors will get complacent if they see the same aircraft every year, it's just human nature, they stop looking like it was a first time inspection which always has a higher level of scrutiny than a repeat aircraft. Builders are especially vulnerable to this type finding, they "know" they built it correctly so why would they need to scrutinize it?

Your life and those of your passengers depends on sound maintenance practices, make sure you give it the time and attention it deserves!

Good post Walt. I couldn't agree more!

And I emphatically agree with Mel's agreement.

Insp.

Walt said:

I think the main point I'd like to see folks take away from this is that every time you do an inspection, especially if you're looking at your own aircraft, is that you really need to take a step back and try to look at things with a "fresh set of eyeballs".

This aircraft was built in 1992 and I have no idea when this part was actually installed, but I can assure you it wasn't recently so it has been overlooked for quite some time.

This is an excellent example of how having someone else do your condition inspections every now and then can be a good thing, owners/inspectors will get complacent if they see the same aircraft every year, it's just human nature, they stop looking like it was a first time inspection which always has a higher level of scrutiny than a repeat aircraft. Builders are especially vulnerable to this type finding, they "know" they built it correctly so why would they need to scrutinize it?

Your life and those of your passengers depends on sound maintenance practices, make sure you give it the time and attention it deserves!

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I wholeheartedly agree! Every other cond. insp. at least, I would have my good friend, (who holds an A&P with Inspection Authorization) follow up my Cond. Inspection. Sometimes he would find something that I had missed! Another set of eyeballs with no "no skin in the game" can save your bacon!

Just a few more observations. Walt you are holding the gascolator in question. What was used to plug the aft port? I can't understand why a builder would do the install this way, however, it has worked for a number of years. I would think the two outlets on the gascolator are to serve two engines and/or one could serve as a primer feed. Do most primer installations come off the top of the gascolator? I have the same gascolator without a primer.

Jim Fogarty
RV-9A Flying

jfogarty said:

Just a few more observations. Walt you are holding the gascolator in question. What was used to plug the aft port? I can't understand why a builder would do the install this way, however, it has worked for a number of years. I would think the two outlets on the gascolator are to serve two engines and/or one could serve as a primer feed. Do most primer installations come off the top of the gascolator? I have the same gascolator without a primer.

Jim Fogarty
RV-9A Flying

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The outlet ports, including the primer port, are both ported out from above the filter screen, the aft inlet ports fuel into the bowl and then fuel flows up thru the screen to the outlet ports. The way is was installed bypassed the screen totally, debris would just pass right through like a piece of tubing. That's why I found debris in the "last chance" carb inlet screen which is what tipped me off to the incorrectly installed gascolator (it was clean).

A hex pipe plug was stuffed in the inlet port and then ground smooth so it would fit flush on the firewall.

The dual outlets I suspect are there so the unit can be mounted on the left or right side of the firewall.

Walt said:

The dual outlets I suspect are there so the unit can be mounted on the left or right side of the firewall.

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Correct.

An earlier version of this gascolator only had a single outlet port (to the right).

Thanks guys, appreciate the post.

Jim Fogarty
RV-9A Flying

Another one!

Thanks Walt for the eye opening tip!
Guess what I found on the latest plane in for panel upgrades & 100hr insp! There will be a bit of plumbing reworks happening too!
If not for your timely post, I might well have not seen this gascolator installation error either, as had happened on this plane's prior 11 builder & A&P annual inspections.

Cheers