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Old 12-05-2011, 08:30 AM
Rick6a's Avatar
Rick6a Rick6a is offline
Join Date: Jan 2005
Location: Lake St. Louis, MO.
Posts: 2,346
Default Ease of Access

Originally Posted by DanH View Post
......Honestly, I have no idea why folks don't finish structure before rigging......
No idea? Obviously, different strokes for different folks. The following thoughts do not apply to quickbuilders. I found that while comfortably seated on a shop stool outside the standard kit airplane, it was far easier to complete the rigging...specifically installing the fuel vent and brake lines before installing the outer skin. Later, the addition of wiring routed through the gear towers easily adds to the clutter making access increasingly difficult. The simplest "workaround" I know of involves the installation of a few structural blind rivets after the side skin is permanently attached. That is a small price I enthusiastically pay. On the other hand, if any talented builder feels more comfortable running, routing and attaching those aluminum lines and all wiring while gaining access through the small lightening holes on the gear towers on a standard, not quickbuild kit....all the while crouched inside the cramped confines of the cockpit, well sir, I freely admit they are more dexterous than I am.

Rick Galati
RV6A N307R"Darla!"
RV-8 N308R "LuLu"
EAA Technical Counselor

Last edited by Rick6a : 12-05-2011 at 09:35 AM.
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Old 12-05-2011, 09:47 AM
mlwynn mlwynn is offline
Join Date: May 2005
Location: San Ramon, CA
Posts: 402
Default Preparation for -4 Cherrymax

To answer Dan, the instructions with the fuselage kit said to delay installing the forward skin until all the wiring was done. I can see in retrospect that the access is not all that bad, especially with the modification of making a door in the rear baggage bulkhead. Still, I think wiring would have been quite a lot more difficult.

To use -4 cherrymax rivets, I can see the ease of reaming the hole to #30. What is the best way to enlarge the dimple? I clearly can't do an additional countersink in the longeron and then dimple the sides. Use a countersink? That would take a little metal off the forward skin. The skin is pretty thin. Suppose that will be structurally sound? Is that how others have handled it?

The -3 cherrymax rivets are available but are not very robust looking. Advice?

I reviewed Rick's previously site post on this. Looks like it worked out okay for him to do a slight machine countersink on the skin. Everyone okay with that?


Michael Wynn
RV 8 finishing
San Ramon, CA

Last edited by mlwynn : 12-05-2011 at 12:07 PM. Reason: More information available
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Old 12-06-2011, 11:20 PM
Join Date: Mar 2008
Location: Seattle
Posts: 1,374

If I recall correctly, the CR3214-4-4 rivets have a small head that fits the original dimple. You only need to enlarge the hole to #30 to fit the rivet body.
The link is an offer for 10 ea CR3214-4-3 with a picture. The head looks small, as I mentioned.
I'm with the structure first, wiring & systems after, but I admit the fuel tank vents were a pain and yours look very nice.
I just feel that you want to add wires etc. after you build structure so you can access them later if needed. After all, working on built-in items you can't get to....would be frustrating.
Scott Emery
EAA 668340, chapter 326 & IAC chapter 67
RV-8 N89SE first flight 12/26/2013
Yak55M, and the wife has an RV-4
There is nothing-absolute nothing-half so much worth doing as simply messing around with Aeroplanes
(with apologies to Ratty)

Last edited by SHIPCHIEF : 12-06-2011 at 11:33 PM. Reason: ad link & detail
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Old 12-07-2011, 08:20 AM
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Rick6a Rick6a is offline
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Location: Lake St. Louis, MO.
Posts: 2,346

Originally Posted by SHIPCHIEF View Post
.....I'm with the structure first, wiring & systems after.....I just feel that you want to add wires etc. after you build structure so you can access them later if needed......

I am not sure what point you are making. You say you prefer the "structure first" approach but as it turns out, for lack of an appropriate bucking bar, you chose to install blind rivets along the upper gear tower anyway. What am I missing? So I am asking. Finding yourself needing to install blind rivets anyway, did you or did you not install the skin first? If you did rivet the skin on (structure first) and needed to use blind rivets anyway, do you not see the irony?

In the end, whatever approach you used (skin on, skin off) really doesn't matter unless you put a premium on much easier access and the undeniable convenience of working from the sitting position on a stool as opposed to folding up the body and finding yourself contorting about the internal structure. Strictly your choice. The quickbuild fuselage does not give you that option because the only choice with the quickbuild fuselage is to fish, route and securely attach those aluminum lines all the while working through small lightening holes. I don't know how you can feel your way through those lightening holes with that soft aluminum tubing without risk of kinking it at some point and then there is the question of neatness. You want those lines to be secure and you don't want anything loose, rubbing or chaffing. A flashlight and mirror becomes your chief means of verifying quality. Obviously, that awkward approach must work because people successfully do it all the time as your average quickbuilder can attest. Personally, when assembling a slow build kit, I'd rather work smarter than harder.

You may have slightly misinterpreted my prior post because I did not suggest nor did I route wires through the gear towers prior to riveting the side skins into place. In my experience, at that point in the assembly process I had little idea what wires or the number of wires to be ultimately routed through the towers. The only prep work I did for that eventuality was to drill a couple of entry and exit holes in the gear towers for the routing of wires to come much later in the assembly process. Yet again, I should point out that not having the skin nailed on (structure first) made drilling the upper regions of the gear towers a much easier task because.....yep, you guessed it.....better access.

You are reasonably correct that the head diameter of the CR3214-4 rivet *will* fit in the original dimple....marginally, I suppose....but it will sit a bit proud. Stickler for detail that I am, achieving optimum surface flushness requires the #40 dimpled hole to be very slightly machine countersunk. A few turns with a hand deburring tool is all it takes, very little material is actually removed. A few shavings at most. Only then will you find that that blind 1/8" dia. Cherry rivet will achieve optimum surface flushness while sitting in an existing #40 dimple just as smoothly and unobtrusively as all the other surrounding rivets.

One last note: For the benefit of other builders who at some point may wish to use CR3214-4 rivets on the gear towers, above the instrument panel or anywhere else, take note. It is easy enough, very easy in fact to quickly test the technique without touching the airplane. First, drill two #40 holes in a scrap piece of .032 aluminum, the same substantial thickness the side skins are. Dimple both holes with a #40 dimple die. Now ream both holes up to #30. Slightly machine countersink one hole, leave the other hole just exactly the way it is. Now test fit Cherry rivets inserted into both holes. Set the fasteners if you want to. Compare the side by side results. Draw your own conclusions.
Rick Galati
RV6A N307R"Darla!"
RV-8 N308R "LuLu"
EAA Technical Counselor

Last edited by Rick6a : 12-07-2011 at 04:16 PM. Reason: clarity
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Old 12-25-2011, 08:21 AM
phapp phapp is offline
Join Date: Mar 2008
Location: Walpole, NH
Posts: 44
Default Aircraft Spruce - Wrong Rivets


For the first time in many years, I had a problem with my Aircraft Spruce order.
Things, happen, so I'm not too upset. I am upset that despite the holiday hours listed on the website, yesterday, Saturday 12/24, I could not get through to customer service despite multiple calls and after 1/2 hour on hold and repeatedly being caller #1 and next in line.

The thing that may be of concern is that they sent the wrong / mismarked rivets. I ordered the 25 pack of CR3212-4-4 and that's what the package said, but they sent the oversize versions: CR3242.

That's only a 15 thousands (.1440 - .1285 = 0.015) difference.

Does anyone see a problem going with them for those too tough to buck rivets on the top skin in the gear tower area? They require a #27 drill.
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Old 12-25-2011, 01:39 PM
CMW CMW is offline
Join Date: Mar 2007
Location: Livermore, CA
Posts: 165


You don't want to use either of those rivets. As Rick pointed out above, the rivet to use is the 3214-4-4. The 3212 has a standard head size, while the 3214 has a reduced head size that is very close to an ad3 rivet. You can get them in packs of ten from General Aircraft Hardware.

RV-8 Wings
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Old 12-25-2011, 06:00 PM
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DanH DanH is offline
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Location: 08A
Posts: 8,076

Originally Posted by Rick6a View Post
... the only choice with the quickbuild fuselage is to fish, route and securely attach those aluminum lines all the while working through small lightening holes.
Not quite. You're aware of the tower access mod.....and the requirement to re-torque gear bolts on a regular basis, standard or QB.

You may have slightly misinterpreted my prior post because I did not suggest nor did I route wires through the gear towers prior to riveting the side skins into place.
So in the context of gear tower access you're only talking about placing the aluminum tubing?
Dan Horton
Barrett IO-390

Last edited by DanH : 12-25-2011 at 06:03 PM.
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Old 12-26-2011, 07:55 AM
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Rick6a Rick6a is offline
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Location: Lake St. Louis, MO.
Posts: 2,346
Default A Tale of Two Towers

Dan H,

I hope I can answer your question satisfactorily. For the sake of clarity, I’m glad you included a pic of a modified gear tower, presumably installed on your quickbuild with its side skins already riveted into place, in the process the factory relieving you from having to complete a substantial amount of sheet metal work yourself. Your detail photo helps make a direct comparison with my unmodified gear tower easier to visualize. Thank you. The quickbuilder realizes that because the factory already installed the forward fuselage side skin, there arises a technical obstacle that must be dealt with later. You see at some point in the instruction manual, standard kit or quickbuild, Van’s will direct the builder to size, route, fit and secure one hydraulic and one fuel vent line co-mingling inside each gear tower. What we all know is that access to complete that plumbing work is severely limited and normally, that work can only be accomplished by gaining access through a series of 3 small lightening holes, often working and assembling components by sense of feel. Challenging task. Not quite as challenging as drilling holes in the canopy or building a leak free fuel tank but it is a challenging task to do right knowing there are a number of ways to complete that job less than correctly.

Now I can easily imagine it was a quickbuild guy who originally came up with the popular gear tower modification (was it you?) if for no other reason than to assure long lasting high quality results with an important section of aircraft plumbing that will forever be obscured from plain view. Pretty simple mod really, in essence, making one lightening hole out of two. I’m all for ease of access. If I purchased a quickbuild, I’d likely do the same thing. Being able to more easily retorque the gear leg bolts is a nice bonus.

But it is important to understand that while my comments, including those words you thought to quote may not be relevant in your experience, those words are entirely consistent with construction realities faced by RV builders choosing to forgo any such modification work, preferring instead to adhere to the directions and specifications called out by the factory drawings and builders manual.

Rick Galati
RV6A N307R"Darla!"
RV-8 N308R "LuLu"
EAA Technical Counselor
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Old 12-26-2011, 09:12 AM
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Capflyer Capflyer is offline
Join Date: Feb 2005
Posts: 1,055
Default Gear Leg Bolts Torque

Sorry this is slightly off topic. I have heard this ocassionally but cannot find it documented where there is a manditory gear bolt torque inspection. Nothing listed on the mother ship site unless I missed it. Can someone please point me in the right direction? I'm trying to decide if the tower mod is something I want to do and now is the time on the current project.
Based in the DC SFRA where the Forces of Darkness gaze upon our every move
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Old 12-26-2011, 08:56 PM
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GAHco GAHco is offline
Join Date: Dec 2006
Location: Paso Robles, CA
Posts: 1,177
Default Stock Items! CR3214-4-*

This is what got us into small packs of Cherrymax and we sell alot!
Here was our post in the thread that started it.

We are working on a new Webstore and it is not out yet.

The current one is still serving, here are the cherrymax that rv8 guys have bought so many of.

You may call us or order from the webstore.
Get em in the Sky!
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28th Anniversary of GAHco March, 2012
Thanks for being part of our success
Dues Paid November 2012

Last edited by GAHco : 12-26-2011 at 09:06 PM.
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