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Hose change and Safety

Roger Lee

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Just my personal FYI and trying to help,



Due to the few that have had issues with carb debris and no absolute proven cause I would highly recommend a safety carb bowl check for the owners.


After a hose change I would pop the bowls at 5 hrs and then at 20 hrs and check for debris. You can have debris sit for months and not cause an issue or it can happen right away. Use the carb removal procedure like it is shown in the maint. video section and it will only take about 15-20 minutes to do them both. I try and take a better video. I know some have used it and it works easily and it's quick. Also remove the banjo bolt that this hose connects to on the cross over balance tube and make sure it is clear. Debris can collect there and not pass through which will cut fuel flow.


Not all hose changed aircraft have carb debris, but it's been a few too many for me around the US.

This is just a piece of mind and safety check that shouldn't cause you any grief, but maybe make you sleep a little better and head off any uncomfortable drop in engine rpms at the wrong time.



The second thing I'm going to try is switch to Aero Quip 1/4" fuel hose for the outlet line off the fuel pump to the cross over balance tube. This is about 14" long.




I have no good information or data to back this up about using this hose here, but I'm have hopes that all debris will disappear. This is the only hose (fuel pump outlet) that can actually introduce debris into our carbs because there are no filters after the pump outlet. Everything else has filters. I have not found any debris in our regular fuel filter in the panel and none in the gascolators and none in the pumps, but for some reason we do at times get a flake or two from this one hose. It is only one of two that we get pressure that feeds the system. One off the bottom of the fuel pump to feed the carbs and the other is the re circulation line, but that one has a .035 orifice in it so debris can't flow down stream.



This will take some time to collect any data so it's a work in progress for a while.



Hey, I guess we could call this a forum SB. ;)

For you legal eagles it isn't even mandatory. :lol:

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  • 3 weeks later...

Here is a thought, what about a secondary inline filter between the carb inlet and the fitting that the hose has been attached to?

The screen mesh would have to be finer than the smallest debris found to date. And would need a bypass in order to maintain fuel flow if the screen should become blocked.



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A standard fuel filter would stop anything big enough that would cause an issue in the Bing main jet and what about the 2"-3" piece of hose after you put in the filter? It would take an LOA. Most of the time filters are upstream of fuel pumps and or other fuel equipment so it doesn't clog them up. I have only seen a couple people with a filter after the pump. If you aren't having an issue then don't worry about it.


I would recommend checking the carb bowls after 5 and then 20 hrs after a hose change. It only takes a few minutes.

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I think I've mentioned before that BMW airhead motorcycles can have similar problems with crud in their Bings.


Many choose to place an inline filter right before the carb (this on an R100GS I had):




Being transparent, you can keep an eye on debris. But being plastic, I might not put it under the cowl of an aircraft, though I have seen similar on Experimental.

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  • 2 years later...

CT's at one time had a plastic inline fuel filter behind the panel near the fuel shut off valve. When FD approved ethanol that filter was replaced with a metal filter that could be taken apart, cleaned, and re-used. Ethanol apparently was causing the plastic filter to deform.

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