FYI Interval for cleaning the breather tube on a CubCrafters Carbon Cub FX-3 with Lycoming 363i

[Neal]

The guidance which I believe comes from CubCrafters is to clean the breather tube inside the exhaust pipe with the provided wire brush at each oil change. I cannot stress enough that is too much time between cleanings. I do mine about every 10 hours, if not more frequently, and today prior to flight I decided to do mine and it was clogged.

Clean it frequently!

P.S. I don't know the official name for that tube we clean out. And when I was at CubCrafters for the 10 hour they had theirs on the end of a drill for even better cleaning capability.

 

[Tsquared]

When I took delivery of my FX3 I was told to clean that tube every 5 hrs, 10 hr at the most. On the few times I’ve exceeded 10 hrs between cleanings mine has been seriously junked up.

Protip - after cleaning the tube, clean the brush with some Avgas and a screw driver tip.

 

[Neal]

Here is the cleaning brush from CubCrafters:

7353T12-Hand-Held LT Breather Tube Brush with SS Bristles

store.cubcrafters.com

I think the important part is this is a tube brush vs. rifle cleaning rod. We don't need bristle brushes coming off inside that tube

I did a quick search on Amazon for tube brushes but if I needed another I'd just get the one from CubCrafters with other parts such as a new ignition backup battery when that time comes, etc.

 

[Neal]

Is this breather tube specific to CubCrafters or do other engines such as the IO-360 have it?

 

[Neal]

A thought comes to mind in that if you intend to fly across the country such as when I brought my FX-3 home you should have this cleaning brush on board. It was 28 hours of flying for me to bring it home.

 

[Tsquared]

Agreed. And when I flew mine home to MN I cleaned it after every other leg. approx 2.5 hr legs. 11.5 hr tt

 

[Hunter]

Are y'all taking the cowling off and removing the hose during each cleaning? When I took delivery of the plane, I was told to just stick the pipe cleaner "up there" and loosen the buildup. Is the concern that you could poke it up too far into the hose?
I've read the service instructions released by cubcrafters, but I'd also like to know if cleaning in a pinch without a full inspection is possible.

I've been running into elevated oil pressure lately, and I'm wondering if this could be a result of buildup.

 

[Neal]

No cowling off, I use a flashlight up the exhaust to find the breather tube and use the tube brush to ensure it's not obstructed and try to clean the soot out as good as I can. I don't think the tube brush is long enough to go "too far" but you'll feel the constricted area if you have build up.

What oil pressure are you seeing? Last night I flew and watched it carefully post oil change and I was at around 81 psi for the flight. I'm using Aeroshell 15W50. What oil is in your engine?

 

[Tsquared]

I’m just pushing the cleaning brush up the tube a few time until I feel any crud loosen up. you can’t push the brush up very far and you will hit enough resistance that will indicate it’s far enough.

I’ve never pulled the cowl or tube off to clean it.

 

[Hunter]

No cowling off, I use a flashlight up the exhaust to find the breather tube and use the tube brush to ensure it's not obstructed and try to clean the soot out as good as I can. I don't think the tube brush is long enough to go "too far" but you'll feel the constricted area if you have build up.

What oil pressure are you seeing? Last night I flew and watched it carefully post oil change and I was at around 81 psi for the flight. I'm using Aeroshell 15W50. What oil is in your engine?

During the run up high 80s (87-89). With oil temp in the green mid to high 80's (85-87)

I use 15W50 and recently did a fresh oil change.

 

[Hunter]

I’m just pushing the cleaning brush up the tube a few time until I feel any crud loosen up. you can’t push the brush up very far and you will hit enough resistance that will indicate it’s far enough.

I’ve never pulled the cowl or tube off to clean it.

Ok, good deal. That's what I've been doing. Last flight I also noticed a small drop in RPM on the right side ignition. Dirty plug? After running it at 2000 rpm and leaning it out for a bit, the drop was minimal (I think around 10-20), but it's at the top of my list next flight to do a thorough check on the ignition (watching EGT change) and oil pressure after a thorough cleaning of the breather.

 

[Neal]

With oil temp in the green mid to high 80's (85-87)

I think you have the numbers wrong on this, green is 122 and above I think, can't remember top of green value. As long as it's in the green.

Last flight I also noticed a small drop in RPM on the right side ignition

I've been hypersensitive about this and had an issue at my first condition inspection where the A&P had an oops on my ignition circuit when we swapped out the seat for the 3rd time due to upholstery issues. Anyways, what I learned is yeah the allowed drop is 50, I've seen 70-80 but the drop really occurs when the key is in between BOTH and L and R, etc. In those transitions you're essentially killing the ignition then enabling it again and that causes a RPM drop. It's also odd that I can hear the RPM change but I don't see it when going between BOTH, R, L in runup tests. Moral is don't be overly sensitive about it, there's nothing you can really do to fix it, I think it's just a test to ensure it's working as expected, what that expectation is really isn't in black and white as to go / no-go. I can tell you that when it's not right you will know which happened from the incident mentioned above.

I replace my plugs at every condition inspection, we're lucky, they're cheap. And after my first condition inspection with the CubCrafters "" service center "" (I put that in quotes for a reason) I wasn't happy with the gapping of the plugs so when I got home I replaced them again. With that said I just replaced mine and they looked terrible and I run LOP and lean at idle. Last night I did a further test of how far I could lean at idle (1000) before the engine got rough and I'm going to be leaning more aggressively at idle/taxi to again try to keep these plugs in the best shape possible. Maybe it's normal that plugs look like this after a year but I'm going to do my best to keep things in top order.

 

[Hunter]

I think you have the numbers wrong on this, green is 122 and above I think, can't remember top of green value. As long as it's in the green

Let me clarify. With my oil temperature in the green arc, oil pressure is measuring in the amber high 80’s (84-89). I reference temp so that you know I’m not reading pressure on a cold-soaked engine.

I've been hypersensitive about this and had an issue at my first condition inspection where the A&P had an oops on my ignition circuit when we swapped out the seat for the 3rd time due to upholstery issues. Anyways, what I learned is yeah the allowed drop is 50, I've seen 70-80 but the drop really occurs when the key is in between BOTH and L and R, etc. In those transitions you're essentially killing the ignition then enabling it again and that causes a RPM drop. It's also odd that I can hear the RPM change but I don't see it when going between BOTH, R, L in runup tests. Moral is don't be overly sensitive about it, there's nothing you can really do to fix it, I think it's just a test to ensure it's working as expected, what that expectation is really isn't in black and white as to go / no-go. I can tell you that when it's not right you will know which happened from the incident

Good to hear. I’ve noticed the same thing. Inbetween positions is where the dip occurs. However, right is lower than left. Much to test out before freaking out phase occurs.

I replace my plugs at every condition inspection, we're lucky, they're cheap. And after my first condition inspection with the CubCrafters "" service center "" (I put that in quotes for a reason) I wasn't happy with the gapping of the plugs so when I got home I replaced them again. With that said I just replaced mine and they looked terrible and I run LOP and lean at idle. Last night I did a further test of how far I could lean at idle (1000) before the engine got rough and I'm going to be leaning more aggressively at idle/taxi to again try to keep these plugs in the best shape possible. Maybe it's normal that plugs look like this after a year but I'm going to do my best to keep things in top order.

Interesting. Are you running the iridiums? I believe they include them now. Thanks for sharing your experience. You’ve calmed me down a bit!

 

[Neal]

Are you running the iridiums? I believe they include them now.

Yes, just ordered another 8 as I keep a set in the toolbox at all times, and two are in the plane in my spares kit.

Amazon product ASIN B000CIY4FM

 

[Hunter]

Thanks! I’m grabbing them. I’m always playing catch-up with parts