Chuck and Ryan's Build Tips

[aeroaddict]

For clarification, maybe mine was binding and I didn't notice when system testing.

My point being that the motor is very difficult to R&R when the plane is covered.

Builders or future builders should check alignment and consider the possiblity of the trim motor failing.

[ceslaw]

Three people with similar misalignment problems for the stab drive system. Did anyone tell CubCrafters about this and, if so, what was the answer?

Andy

Per Pete at Cub Crafters no reports have been received of any issues with the trim system.

[ceslaw]

For clarification, maybe mine was binding and I didn't notice when system testing.

My point being that the motor is very difficult to R&R when the plane is covered.

Builders or future builders should check alignment and consider the possiblity of the trim motor failing.

Dan:

Good point. That motor has so much torque that I suspect it overcomes a bit of misalignment and most builders may never be aware of it.

I suspect it is not necessary, but I can see a couple of ways of smoothing beyond what I did. First a connection between the jack screw and the motor that had a bit of flexibility rather than being so rigid would help. Alternatively, the motor assembly could be mounted with rubber spacer or something that would flex a bit. I was not inclined to pursue either option since I prefer not to deviate from CC design on flight related parts.

Your idea of something other than the roll pin to make replacement down the road easier is a good thought.

[ceslaw]

I had exactly the same difficulties and I brought more or less the same solutions. I will write a detailed post on this subject.

Looking forward to your post!

[ceslaw]

Continuity

Dave Embry has underscored the need to check wiring to assure it is working before covering the aircraft in his excellent build posts. Good advice.

Checking continuity after the wire harnesses are in place assure they were not damaged during installation. Here is a simple way to do it. On one end two of the wires are clipped together.

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On the other end a VOM is used to check for a closed circuit – zero ohms – for the corresponding wires clipped at the other end.

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This is repeated for multiple pairs. Non shorted connections are also checked to make sure they are open circuits. When finished the plug is marked so we won’t forget this task has been done. Continuity confirmed.

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[ceslaw]

Boot cowl.

After the Cub has been flying for a year or so, the insulation and vinyl on the top inside of the fire wall will start to separate and the top section of black vinyl will flop aft. It is not a big deal since the thin bit of insulation is likely of limited value and all the grommets hold most of it in place, but we found a simple way to keep that top portion secure.

Click Bond makes threaded screws with large flat heads that glue into place to provide convenient screw locations without having to drill holes. I used them on the rear clip of the GT-40 directly above the headers to hold an insulated panel and they have worked well despite exposure to extreme temperatures. We decided to try them on the inside of the boot cowl.

The Click Bond kit we used comes with six studs, 23/32” long, 10/32 threads. All six were used, spaced around the top and upper sides, adjacent to the outer perimeter. The kit is available from Aircraft Spruce for around $33. Part number 04-06020.

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Once glued in place matching holes were cut in the vinyl with an Xacto knife using a quarter inch washer as a guide. The insulation was slit with an Xacto knife. One and quarter inch nylon washers were used since they weigh virtually nothing compared to fender washers. The Nyloc nuts that come with the Click Bond kit will be tightened just enough to hold the vinyl and insulation in place without squishing it when the final assembly is completed.

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[ceslaw]

Extra rivets

The aft end side of the wing ribs have a pair of holes on the top and bottom that look like they should be match drilled and riveted. Cubcrafters advised, however, that no rivets are used in this location on the EX2; rather they are used only on the heavier gross planes. But not wanting to let a good hole go to waste we decided to go ahead and add the rivets acknowledging this will add a few grams to the total weight.

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The rivets are AN470A-3-3.

[ceslaw]

Inflation Update. The balloon technique for determining the integrity of the fuel system was first described more than seven years ago. https://forum.cubcrafters.com/showth...ll=1#post10727

Back then we were satisfied that remaining inflated for three or four days was sufficient to confirm no leaks. Later when the plane was flown a very slow seepage of fuel from the selector valve became apparent leading to the discovery that the valve had been manufactured with wrong size O rings. Several other builders made the same discovery.

On our current build, per Dave Embry’s suggestion, we dismantled the fuel valve, checked the O rings size, lubricated them with O ring lube, and only then was it installed. Next, we extended the balloon test to a full thirty days. Party balloons inevitably deflate over time, but these remained nearly fully inflated for that time, so the fuel system should indeed be free of leaks.

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Time to pop the balloons.

[ceslaw]

Extended Baggage. Long ago on this forum tips were posted including adding additional tie downs and a simple floor mat. https://forum.cubcrafters.com/showth...ll=1#post10790 https://forum.cubcrafters.com/showth...ll=1#post10838.

Here are a couple more tips.

1. A pair of nut plates (MS21059L08) were installed at the aft end of the baggage compartment floor. Why you ask? Because experience revealed that floor mats may shift slightly and it is best to anchor them. We prefer not to use tape or glue.

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Menards stocks a very light unbacked carpet material which we opted to use in place of the rubber mat described in our previous post. The color match is ideal.

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2. The Carbon Cub EX2 now comes with attachment points for a ballistic parachute. Since that is not an option we ordered, it would be a shame to let those attachment points go to waste. One is nicely centered on the left side and two are along the left side top edge. So why not add another tie down connection? The threaded connection matches that used with the Cubcrafter’s tie downs. Or at a minimum add screws to those locations to add mechanical attachment points tying the panel to the frame.

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[PBY Catalina]

Very good Chuck, thanks.

About those two ones ? How did you attached them :

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