RV-8 and the 2026 Condition Inspection, Continued

To see how this whole thing started, start here. At the bottom of each post is a link to the next one, until there isn't.

Looks like it shrunk in the dryer.

4/25/26 - 5/3/26 The span on this post is longer than the others because I have actually made significant progress and there is less to report.

The last weekend in April I was finally able to get almost everything back together. Now that the new shock mounts are installed, I removed the last two intake tubes (#2 and #4) and replaced the O-rings on them, then reinstalled them. I then reinstalled the #3 and #4 tubes that had been removed to Facilitate Other Maintenance (FOM).

The next task was to reinstall the exhaust system. I had removed three of the four pipes plus the collector. It wasn't too hard getting them off, they weren't frozen, but it did take some tug of war. Applying some penetrating oil, in this case Mouse Milk, helped make getting them off easier.

I know that the pipes should be installed with some sort of Anti-Seize compound, but I was never sure exactly what to use. McFarlane came out with their own lube that they call D A M Exhaust Lube which was created specifically for aircraft exhaust systems. It comes in a small can with an applicator in the top. It is very thin and runs all over, but they say to apply it to both sides of a joint before assembling.

It dries quickly and leaves a grey powder behind. That makes sense, since they call it a dry lube. They say that you can thin it and apply to the assembled joints periodically to keep them lubricated. I tried this once and it is very messy, so I went back to using Mouse Milk. There is much debate on the interwebs as to how effective, if at all, Mouse Milk is in this application. It is essentially a penetrating oil and mostly cooks off when the engine is started, but I think it may help because I have never had a frozen joint and my exhaust system has almost 2,500 hours over 25 years and it comes apart easily and there have been no cracks.

The next thing that I tackled was to inspect and clean the gascolator filter. I have the Andair gascolator that uses a filter rather than a screen like most gascolators.

Gascolator, bowl, and filter.

I usually take the whole thing out to do this on the work bench. The first time I did it, I tried doing it on the airplane. It worked OK until I tried to put the bowl back on. Since it sits so close to the firewall, there is very little room to get hold of anything and I managed to cut the O-Ring putting the bowl back in and that led to a whole thing.

Not much room there to grab anything.

Now, doing it this way has also lead to a thing. When I went to put the Gascolator back in, I couldn't get the fuel feed line nut onto the fitting. The nut wouldn't slide over the flare at the end of the tube.

The flare should be a bit smaller than the threads on the nut.

In fact, as I was digging out the tubing tools to make a new one, I found a chart that showed what the correct diameter of a properly made flare should be. For 3/8" tubing, which I am using, it should be between .046" and .049". The one that I had was almost .053". Well, no wonder it doesn't work.

It's a little hard to see in this photo, but the sleeve had dug a groove in the outside of the flare.

It turns out that I had been over-tightening this nut for the last several years and it had actually caused the flare to deform and get wider. I also found torque specs for the aluminum fittings and for 3/8" lines, they are only supposed to be torqued to 75-125 inch pounds. I had been using more than that. I have to be more careful in the future.

I had considered trying to whittle the flare down to where it would fit, but in addition to the size, the sleeve had dug a groove in the back of the flare and I was afraid it would crack over time. I didn't have any 3/8" tubing around the hangar, so I had to order some more, which means it will be next week before I get this all put back together.

Once again I was faced with an issue getting needed supplies. In years past, with Van's being so close, I could place an order for small parts over the weekend and have them by the following weekend. Alas, that is no longer the case. As of the end of the week, they still hadn't shipped the tubing I ordered. I ordered some from Aircraft Spruce and had to spring for 2-day delivery to have it by Friday.

Fortunately I had the nuts and sleeves on hand. I could have cut them off of the old line and reuse them, but I didn't.

Fuel line "kit".

I knew that once I started, it wouldn't take too long to make, so I wanted to get to it. The plans call for using 3003-O soft aluminum tube for this type of line. Because it is soft, it is easy to form, but also because it is soft, it comes rolled rather than straight. My Dad pointed out that there is such a thing as a tubing straightener, but I didn't learn this in time to use on this one. I will go ahead and get one to have for next time.

I ended up using the old school, low tech method of straightening. I got it as straight as I could by hand and then used a scrap piece of 2X4 and rolled the tube between the wood and the table. This gets it about 98% straight. Since I am just going to bend it once it is straight, this is good enough.

Manual tubing straightener.

The folks at DarkAero put out a good video on bending and flaring tubing for aluminum fuel lines using the exact tools and methods I use, so I didn't document that part. I did what he did.

The new line installed and ready to use.

Once that was done, I finished up the tail and put the panels and fairing back on then started in on the fuselage. I think I should be ready about the time the propeller is finished. I hope.

The next exciting chapter can be found here.