<Archive Thread> Building the EX3 - Tips & Hints

[Daveembry]

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Thanks for the warning. From the symptoms I would suspect a fractured rather than blown fuse. Slight heating from normal current and the fuse expands opening the fracture. Cool down and it works again.

yeah....i guess that would make sense. After it starting to work again the first time, I was very wary as to what was going on as normally, these things don't "fix themselves". I probably had it on after the first time that it started working again.....for 45 minutes or more with all the data base, software updates, etc. I turned it on the next to last time and it worked and 15 minutes later turned it on again and this time is was out for the count. Hard to see but here is what it looks like.....

[PBY Catalina]

FITTING INTERIOR PANELS

Next you will be glad you jumped ahead and fitted the interior panel now instead of on Page 59 of the FINISH MANUAL. .......

Thanks for the advice to pre-position the panels before covering because I’m facing big adjustments needed, and I wonder how I could have done this later!
(cfr:https://forum.cubcrafters.com/showth...or-side-panels)


But questions, Dave: why removing them?
And why not adjusting them and definitely leaving them in place before covering?
What other difficulties should I anticipate if I do this?
At least the right center and front ones ?
(I'm building an EX2)

Thanks !
Y.

[Daveembry]

You are really moving along on your build!!

OK.....

1. There is alot of building you will be doing between now and the finish of the airplane. If you haven't noticed yet, the carbon fiber floorboard and interior panels scratch very easily, so removing them will protect them.

2. Also, you have to cover the fuse yet......so the fabric will be wrapping around these interior areas where the panels sit. So be sure and don't install any of the velcro yet on the top areas. You will then also need to apply the polybrush/spray/paint on these areas.

3. One last thing.....I install the interior panel as the very last thing I do before flying it. I like to get the airplane to the point where the wings and fuel lines are all connected. I then put fuel in (see my post on that subject) to measure the true "unused" fuel and to also check for any leaks in any of the connections. I don't install any of the wing root pieces that would cover up any of this either. I then take the fuel selector and rotate it around in all the different positions. I do this many times and leave the fuel always either on both, left or right for periods of time (like days) to be sure that the fuel selector valve does not leak in any position and over time. Since the left interior panels are not on yet, you can simple look or touch all the fuel line connections and the fuel valve to see if any fuel as seeped or leaked out. I even leave a blue shop paper towel under the fuel selector valve until the time I install the interior panels right before my first flight or inspection fy FAA.

The reason is that out of the 6 airplanes I've built.....2 have had very slow fuel seepage out of the fuel selector valve that did not show up for months!!! It did't drip...it "seeped" very slowly. When rebuilding the selectors.....both times I've found the orings were dry and had a white powdery substance and this was causing the leaks. I replaced and lubricated (with oring grease) the orings. Since then, I check every new fuel valve FIRST to be sure they are lubricated and not dried out. I also found out that is a common problem and on many of the new valves as they may have been sitting on a shelf for a long time. Also.......many mechanics will tell you to never drain your fuel dry and leave the selector valve dry as this will happen.

When the fuel "seeps" over weeks or months, it will go down and hit the side, carbon fiber longeron there where it meet the forward part of the fuse and inside the left fabric spacer where it will collect until the blue fuel will eventually seep through even polyurethane paint and then bubble. Then you get to touch up the polyurethane which is not fun.

I have even gone so far as to now install a heavy piece of plastic sheeting between the fuel valve and the fabric that drapes down and overlaps the floorboard. It's sandwiched between the floorboard (where it rises) and the interior panel and cut off flush with the bottom of the panel. Then.......if the valve ever does leak....the blue stain will appear on the floorboard where you can detect it instead of marring your paint job. (right Chuck?)

Hope that helps!

Thanks for the advice to pre-position the panels before covering because I’m facing big adjustments needed, and I wonder how I could have done this later!
(cfr:https://forum.cubcrafters.com/showth...or-side-panels)


But questions, Dave: why removing them?
And why not adjusting them and definitely leaving them in place before covering?
What other difficulties should I anticipate if I do this?
At least the right center and front ones ?
(I'm building an EX2)

Thanks !
Y.

[PBY Catalina]

You are really moving along on your build!!
OK.....
....
Hope that helps!

A lot !

[ceslaw]

Yup. That's right!. Turned out the wrong thickness O rings had been used. I will indeed take the fuel selector apart and check it before final installation, which is not a difficult task.

Curious as to what you use to lubricate the O rings?

Deferring placement of the interior panel until everything has been confirmed leak free is an excellent idea.

[Daveembry]

EBE0BA57-090F-44CF-BD9D-1B3C832C355A.jpg

this is what was recommended.

Yup. That's right!. Turned out the wrong thickness O rings had been used. I will indeed take the fuel selector apart and check it before final installation, which is not a difficult task.

Curious as to what you use to lubricate the O rings?

Deferring placement of the interior panel until everything has been confirmed leak free is an excellent idea.

[ceslaw]

Excellent. Amazon will deliver a tube to me tomorrow. Thanks.

[PBY Catalina]

... I will indeed take the fuel selector apart and check it before final installation, which is not a difficult task....

Too late for me... installed !

I'm going to stop building and wait you to overtake me !

[Daveembry]

Its pretty easy to do and you don’t have to remove the fuel selector. Here’s a couple screenshots from the Maintenance Manual (page 185 of pdf). Just take a plastic bag or something and wrap around it when sliding it out. Those “little balls” like to fly everywhere if they get away from you.

I use Parker O-Lube to lube orings. All the ones I've checked has some white "chalky" powder on the orings. Looks like a grease that dried out. The orings have seemed to be fine and I just cleaned and relubed them and put them back in.

Orings: If you need to replace the orings, Aircraft Spruce has them. The larger ones are #6 MS29513-114 and the smaller ones are #5 M83248/1-011.

Here is a parts list from the manufacturer (Thanks Trey Hayden for finding this).


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Too late for me... installed !

I'm going to stop building and wait you to overtake me !

[c130jake]

Excellent. Amazon will deliver a tube to me tomorrow. Thanks.

Chuck, you building another one? I’m helping my buddy build an EX3. Not sure what I will build next now that Vans announced the RV15.

Jake


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