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  #1  
Old 09-30-2021, 09:51 PM
claycookiemonster's Avatar
claycookiemonster claycookiemonster is offline
 
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Location: Old Saybrook, CT
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Default Van's Fuel Tank Sealing video vs my reality

Firstly, the video (easily available on You Tube) is wonderful! No hedging my appreciation for seeing before doing. I watched and rehearsed several times before doing it.

Secondly, just an FYI, I was finishing up project tanks which were completed up to the baffle installation. I attempted to "leak test" just the nose of both tanks before the baffle installation by resting them in the assembly cradles, surrounded by brown craft paper with water up to the vent line. The water was dyed red to make leaks more obvious, but none were found. Not much hydrostatic "head" but better than nothing.

I used 50cc veterinary syringes to hold the mixed Proseal. They are fine, and the exit of the nozzle is 3/16ths, so - perfect. They are a bit cumbersome to fill, and then initially really a two hand job to squeeze a bead out of them. I found that each tank baffle installation could be done in less than 90 cc of Proseal. So, I mixed up 1 1/2 syringes and got busy.

Be ready: have your garbage bags or bins open and ready so you can throw sticky things adhering to you there without having to hold anything else. Have boxes of rubber gloves opened and ready. Have several rolls of paper towels ready. Have all the popsicle sticks or tongue depressors ready. I'd recommend a small open jar of MEK because your squeezer dies will get sticky and dropping them in MEK will help. Set the music and put your phone away. Go to the bathroom. I found that each baffle installation from start to finish took about 3 hours. Forewarned.

The initial move of laying down the perimeter bead and dropping the baffle on it was fine. Just as the video shows. All parts were cleaned ferociously first and all points where Proseal might want to adhere to aluminum were scratched up with Scotch Brite Pads first.

The next step was challenging. The video talks about "twirling" the AD-41H closed-end rivets into the holes with a bit of Proseal on the shafts to create a seal.My frustration was that they didn't actually easily "twirl" into the holes, despite clecoes in all other holes from baffle to rib. These rivets are NOT tapered, but rather sharp on the edges, so they do not help aligning rib to baffle. What do you do? The baffle has been dropped in place. It's aligned by other clecoes, and yet the AD-41H's (with a coating of Proseal) do NOT want to go easily into the hole. I'm not sure if Van's reamed or relived these holes prior to installation. All I can say is that some FORCE was required via the rivet puller to get them down into the holes. It worked, but I'm going to lay a dome over these rivet heads as I finish up. Because.

The AN-470 AD-4-4 solid rivets on the outer ribs generally went well, though I think the previous owner of my project did not drill out these to full size. Did you remember to do this? What's one more #30 drill covered with Proseal?
At this point, with pull rivets on the baffle to rib, and solid rivets on the outer rib to baffle, I turned the tanks baffle-side down to encourage the Proseal to ooze down. It's a bit of a PITA to rivet upside down, but laying the tanks across the cradle (actually both cradles) allowed me to get the skin-to-baffle 426 AD 3-3.5 rivets while imagining the sealant flowing down perfectly to cover all sins. (Leak testing not done yet. Stay tuned)

Seriously, other than the unexpected drama of the closed end rivets not wanting to easily "twirl" into their homes, all went well. Daytime temps here in UT are mid 60's, so I'm giving the baffles a week to get to know their new neighbors.

Tomorrow will be "Z" brackets, and I'm anticipating the same problems with the longer AD 44-H rivets to attach the "Z" brackets to the baffle. I do not know what help that anticipation will be, other than to minimize the nervous breakdown I experienced yesterday.

After that will be access plates and senders. Yes, I know: "twirl" the screws through Proseal so the threads are sealed too.

Tanks. Tanks a lot.
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  #2  
Old 09-30-2021, 10:48 PM
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Bernardo Bernardo is offline
 
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I'm firmly in the camp that Van's sealant gun is well worth 17 dollars.

Scott's video is full of terrific insights and is a must-watch... but I'd also recommend these two videos: a quick one showing how the pre-packaged tube is mixed for the gun, and this one (skip to about 13:30) about how easy it is to use the gun and not make a giant mess.

The disadvantage is that you can't really use it for small jobs (unless you find a small disposable container that fits in the gun, and a nozzle for it). But for doing something like a whole fuel tank, it makes life easier.
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Last edited by Bernardo : 09-30-2021 at 10:51 PM.
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  #3  
Old 10-01-2021, 10:47 AM
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wcalvert wcalvert is offline
 
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Small batches of sealant mixed on a metal plate with a spatula, then scooped into a zip top bag (lots left from parts packaging), snip the end and squeeze away. Toss when complete.

Cost is 0, mess is small, and a smallish bag is easy to navigate in any tight spot.

Like the OP said, just like painting etc., it's super important to have your setup ready to go, Mise en place style.

Have a good stand to hold the tank, and expect to take an hour or so for each rib ... think I would do 3 a session and be done for the day.

Wipe your rivet gun tool often to prevent slipping on the ooze out.

Very doable, best of luck on your pressure tests!
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  #4  
Old 10-01-2021, 02:20 PM
Presmini Presmini is offline
 
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Great tips and wonderfully visual story telling. I’m still a few months away from this work but will bookmark for future anxiety reducing tips before starting. Good luck and I look forward to hearing about the end results!
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  #5  
Old 10-01-2021, 04:24 PM
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wirejock wirejock is offline
 
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Default Tanks

Excellent tips and nice writing style.

I too used the syringes. I put it in my caulk gun for some extra torque. Mostly I just mixed in a cup and applied with tongue depressors. Amounts per rib were almost exactly the same.
I noticed the baffle rivet issue early and used a bunch of rivets to hold position. Apparently the clekos were allowing some alignment drift.
For those coming behind, there are sealed nut plates. Very handy. Install them, seal them and screws can't leak past threads from inside. No problem removing screws.
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  #6  
Old 10-01-2021, 04:45 PM
nohoflyer nohoflyer is offline
 
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Quote:
Originally Posted by wirejock View Post
Excellent tips and nice writing style.

I too used the syringes. I put it in my caulk gun for some extra torque. Mostly I just mixed in a cup and applied with tongue depressors. Amounts per rib were almost exactly the same.
I noticed the baffle rivet issue early and used a bunch of rivets to hold position. Apparently the clekos were allowing some alignment drift.
For those coming behind, there are sealed nut plates. Very handy. Install them, seal them and screws can't leak past threads from inside. No problem removing screws.
Where do you recommend that we install the nut plates? Are you suggesting using screws instead of the pop rivets on the baffle? Iím right at this point.
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  #7  
Old 10-01-2021, 05:43 PM
David Paule David Paule is online now
 
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Have a look at this post.

Dave
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  #8  
Old 10-01-2021, 06:13 PM
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wirejock wirejock is offline
 
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Default Nut plates

Quote:
Originally Posted by nohoflyer View Post
Where do you recommend that we install the nut plates? Are you suggesting using screws instead of the pop rivets on the baffle? Iím right at this point.
Sorry, no. NAS1473A08
They take the place of the standard nutplates for the Access Panel. Since they're sealed, the screws don't need proseal. They have an integral rubber seal but I prosealed them and added proseal around the outer edge. My Mentor gave me the tip.
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Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #9  
Old 10-01-2021, 07:15 PM
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claycookiemonster claycookiemonster is offline
 
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Day 2 of Tank sealing.

All "Z" brackets are now sealed and riveted in place. One T-708 access plate is in place as well. Ran out of time and sealant to do more.

Be EXTRA careful that your "Z" brackets are oriented correctly! Between the "relative to the spar, or relative to the tank?" question, there's "top down, or bottom up?" too. Just take your time.

The closed in rivets did much better today, maybe they heard me crying in my sleep last night. The video shows placing two rivets, swirled in sealant, into the end holes of the "Z" brackets to act as "pins" to locate things, and this worked like a charm! It's tedious, but not overly challenging. Most rivets did indeed twirl into their holes. A few resisted, but resistance was futile, and eventually they submitted. I used the wedge tool I made from the trailing edge piece, and it was fine.

I had enough sealant to place one access plate. Twirled sealant into the threads of the socket head cap screws I substituted for the supplied screws. (When was the last time you heard the word "twirled" this many times on this site?)

Finding the receiving holes on the end rib is harder than you'd think once everything is gooped up, so go easy on the sealant or mark them or something. You will generate a big build up on sealant that does not go down into the threads when you screw the cover down. So, the screws will be sealed no problem, but be careful to remove sealant from the hex head or screw head so they're not caked with cured sealant the next time you need to unscrew them. Q-tips with MEK did the trick.

After I was done, and just before I walked away, I remembered all the trouble I went to orient the tanks so that the baffle sealant would sink back into the joints. Which way to orient the tank now? I decided that sealant inside the tank is my best friend, so I placed the tank on end with the access plate down. Hopefully whatever sealant oozed out on the inside will settle down against the T-708 and fall asleep there. Forever.

One more day to finish up and then I'm done with Proseal FOREVER. (jinx)
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USAF: T-38, F-111F
American Airlines: 727, MD80, 757, 767, 737
RV8 #81751 project sold
RV8 #81651 project acquired
https://theonceandfutureflyer.wordpress.com/
Donations up to date thru December 2015

"...serenity...courage...and wisdom..."
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  #10  
Old 10-01-2021, 07:24 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
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Default Tank tip

Here's another tip.
Sometimes theres a bit of excess sealant that can interfere with the tanks fitting against the spar cap. Let the sealant cure a couple days. Place some strips of wax paper along the spar cap where the baffle sealant fillet gets close. Mount the tank with 1/2 the screws. Leave it overnight. Next day pull the tank and allow it to finish curing. Fillets should be shaped to fit perfect against the spar cap.
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Estes Park, CO
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Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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