VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-9/9A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-28-2018, 05:38 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default Extending My RV-9A Fuel Tanks: Documented

I posted before how concerned I am over the quality of Van's quick build tanks due to all the reports I have read over the years of leaks developing, along with fuel vent lines dripping, some puking large amounts of fuel after fueling, so I decided right off the bat that I was going to do a preemptive strike by opening up all the bays on mine and resealing them. I also decided that since I am in the process, I may as well extend the tanks by 12" for about 3.5 more gallons per side. I would not fill them completely on a regular basis, only for XC trips where I want the extended range for longer legs or longer reserves for weather diverting or other reasons. Looked into the extended range tanks but they are pricey and more complicated due to additional plumbing and transfer pumps. I originally wanted to extend the inboard end of the tanks, and then shifting the tank outboard. Once I got the tanks off I realized that would not be possible without drilling all new Z bracket holes in the spar, along with the fact that the tank skin screw holes are spaced closer together on the inboard end. Nothing would line up! I decided to remove the filler, use a couple small pieces of skin aluminum and plug up the hole flush and relocate the filler in the new bay.

The wings are unpainted and still in the rack, so it only took an hour to remove the tanks. Ready for surgery.
[IMG]DSC02024 by David C, on Flickr[/IMG]
Parts needed arrived from Van's. Unfortunately the packers missed packing several items in the wood crate, including the tank skin! Something to do with the flu going around at Van's and everyone pitching in to fill the voids. Oh well, the missing stuff is on its way.
[IMG]DSC02025 by David C, on Flickr[/IMG]
I centered a 1/4" pilot hole in the outboard bay baffle and used a 5" hole saw to open it up. The tank is upside down in this photo and I measure the distance from the top tank skin to the bottom of the vent line. No wonder people complain about dripping fuel vents. Any fuel above the lowest part of the vent line opening is going to come out. That's about 5/8" on this tank. Over fill the tank and its going to come out!
[IMG]DSC02029 by David C, on Flickr[/IMG]
Just an example of a possible leak source in the first bay. You can see an air bubble that formed in the sealant next to the rib flange.
[IMG]DSC02030 by David C, on Flickr[/IMG]
No filet of sealant extending over the rib flange onto the tank skin. You can also see the shine of the rivet shop head the sealant is so thin.
[IMG]DSC02031 by David C, on Flickr[/IMG]
The outboard end rib and filler flange. Again,,, air bubbles/pin holes in the sealant, the fillet is pretty much wiped away, and you can see the rivet shine right through the sealant on the filler flange rivet.
[IMG]DSC02032 by David C, on Flickr[/IMG]

Continued,,,,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #2  
Old 02-28-2018, 05:48 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default More info

Drilled fuel flow holes in the outboard end rib to match those in the inner tank ribs. May as well use it,,,its already there.
[IMG]DSC02033 by David C, on Flickr[/IMG]
I drilled out the rivets on the filler flange, dug a 1" wide sharp putty knife under the sealant covering those rivets for a start, reached in with my hand and peeled the sealant off with little effort. Hardly ANY mechanical bond!
[IMG]DSC02036 by David C, on Flickr[/IMG]
I flipped the tank over so the filler was on top and warmed the area up good with my heat gun. Slipped the putty knife between the tank skin and the flange in a couple spots and the flange popped right off,,,,,again with very little effort. You can see that there mas no scuffing of the aluminum flange or tank skin to assist in making a good mechanical bond. Did the even clean the parts first with solvent to get rid of any oil or contaminates? Makes me wonder. Tank interior side of flange.
[IMG]DSC02037 by David C, on Flickr[/IMG]
Tank skin to flange mating surface. Smooth and shiny as a wet babies butt. Hardly any adhesion.
[IMG]DSC02038 by David C, on Flickr[/IMG]
Aircraft Spruce carries a sealant remover,,,$24 for 6 oz! Wonder what this stuff will do to get rid of the old sealant. Its made for airplanes and I already have it in the shop.
[IMG]DSC02039 by David C, on Flickr[/IMG]
Covered the sealant with a thick layer of remover and let it dwell for 15 minutes. I could see it starting to work in just a couple of minutes but let it do its thing before attempting to remove the mess.
[IMG]DSC02040 by David C, on Flickr[/IMG]

Continued,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #3  
Old 02-28-2018, 06:02 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default More Info,,,,,,,

15 minutes of dwell time pass and I used a razor blade as a scraper. After a couple minutes work it was all removed. I wiped everything down several times with acetone and water to make sure no stripper remained on the aluminum surface. Look at that shine on the mating surface. Absolutely no preparation done for a good bond. The only marks in the skin are from the razor scraping the sealant off. I will cut out an aluminum patch for the filler hole and use the filler flange to match drill it. I'll prep the mating surfaces with a scotchbrite pad and get that sealed and riveted in, then cut out and install a skin circle to make it flush again. This won't happen though until I have everything else opened up and need to get into the FlameMaster.
[IMG]DSC02042 by David C, on Flickr[/IMG]

I will start opening up the other bays tomorrow and report what I find.

To be continued,,,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #4  
Old 03-01-2018, 06:10 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default Update: 03/01/18

5 hours logged in the shop today working on the tanks. I gat all 12 bays opened up, cleaned up, match drilled the cover plates, de-burred it all and prepped the mating/sealant surfaces with 200 grit paper. I removed the filler flange from the other tank easier than the first. I did not even bother trying to remove any sealant first. I just drilled out the rivets, heated the area up gently with a heat gun, slipped the putty knife in two times and gave it a twist. Popped right off with little effort at all. Once again, no signs of any prep work for the sealing/mating surfaces.
[IMG]DSC02043 by David C, on Flickr[/IMG]
I cleaned up the filler flange sealant same as before with the Aircraft Stripper. Great stuff! So now I turn my attention to the vent line and fitting. Disconnected it from the inside and pulled the line out. This is an older Quick Build kit so there is no anti-rotation clip for the bulkhead fitting nut. After I removed the nut and backing washer, you can see in the photo that it was not even tightened down enough to lay flat on the end rib. Look at the area with NO sealant! No sealant on the nut to prevent it from loosening either. It is of no wonder there are so many reports on the forum here of them coming loose and/or leaking. Just a little bit of sealant where the fitting passes through the rib may have created a seal,,,,,but for how long?
[IMG]DSC02044 by David C, on Flickr[/IMG]
Photo of the vent line bulkhead fitting as removed. I have no idea how this tank passed any kind of a leak test.
[IMG]DSC02046 by David C, on Flickr[/IMG]
[IMG]DSC02047 by David C, on Flickr[/IMG]
A photo of a typical rib in both tanks. Most have voids of sealant in the filets here and there . There may, or may not be sealant under the ribs in these areas that isolate the rivets from fuel, but all ribs and surrounding tank skins will get prepped and cleaned for a nice filet of sealant. Man am I glad I decided to do this now before I had to later.
[IMG]DSC02048 by David C, on Flickr[/IMG]
The tank skins are .032", as is the rear tank baffle, so I used part of the new baffle to fab up the backer circles and filler slugs for the now vacant filler holes. A couple minutes on the drill press with appropriate sized hole saws, with the pilot drill removed, gave me perfectly sized backers and fillers. The baffle was clamped to the drill press table with a plywood backer to finish the cut. I match drilled the backers to the filler flanges and dimpled the holes. It won't be as pretty as a tank without a patch, but it will look "Aircraft Grade" and "professionally" done.
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #5  
Old 03-02-2018, 09:35 AM
airguy's Avatar
airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,139
Default

Wow.

The QB proseal work evident there is .... troubling.

I'm very glad now that I built my own tanks. I kept the standard inboard tanks and simply converted the entire outboard leading edges to another set of tanks, 15.5 gallons each side.
__________________
Greg Niehues - VAF 2018 dues paid
Garden City, TX
N16GN flying! http://websites.expercraft.com/airguy/
Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
Reply With Quote
  #6  
Old 03-02-2018, 10:32 AM
RVbySDI's Avatar
RVbySDI RVbySDI is offline
 
Join Date: May 2005
Location: Tuttle, Oklahoma
Posts: 2,484
Default

Interesting reports of quick build tanks. The amount of work you have already put into these tanks hopefully shows that it would not be that much more difficult for anyone building to build their own tanks.

I recall when I built my tanks I was extremely nervous and concerned about building the tanks. I was concerned about the mess, whether I was adequately mixing the sealant correctly, whether I was using enough/too much sealant. In other words, I had very little confidence in my own abilities. But then, a funny thing happens with confidence.

Once one just dives in and starts doing the thing that frightens us the most, we find out it really wasn't as bad as we had led ourselves to believe it would be. That is exactly what happened to me. Yes, the sealant was messy. Even so, it still wasn't as bad as I convinced myself it would be. Yes, it was a learning experience finding out how just exactly I needed to mix the two part sealant. Yet, when I did it a few times I devised a system that worked for me. I learned how much sealant was enough. I LEARNED! And you know, it really wasn't that bad after all!

It is really interesting to see what you are finding in your pre-built tanks. There will always be times when it might be wise to have someone else do the work for you. In the case of these tanks though, I would say, it really is not all that difficult to do once one gets started. Just go for it and before one realizes it, the task is completed. True there is a lot of new technique to learn, new things to understand, new experiences, but hey that really is one of the important reasons why we are choosing to build our own airplanes. At least that was, and still is, my belief about the building process I undertook.

So, for anyone reading this thread who was thinking they should just buy tanks already built instead of building their own, well, maybe you might reconsider and do the NIKE thing! For those out there old enough to remember JUST DO IT!

"And it wouldn't hurt to stop eating like a pig either!", PRICELESS!!
__________________
RVBYSDI
Steve
RV9A
Live Long And Prosper! 🖖🏻

Last edited by RVbySDI : 03-02-2018 at 10:37 AM.
Reply With Quote
  #7  
Old 03-02-2018, 11:11 AM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default

You are so right about the "fear Factor" getting in the way of a builders progress. It does not matter what part of the build, if a builder has no confidence or is apprehensive about tackling that part of the build because it is something they are unfamiliar with, they tend to keep putting it off to the point that they literally come to a stand still. One of the biggies on this forum is when folks get to the fiberglass phase of their project. Some people freak out and are afraid to even make an attempt at it. Fiberglass is in fact a very EZ medium to work in. You can fix virtually any mistake instead of throwing parts away! I am VERY concerned over the poor quality of workmanship I have found so far on these tanks in so many areas,,,particularly on that vent line fitting. Van's website states that these factory workers in the Philippines, where the quick build kits are assembled, make the equivalent of about $8 U.S. dollars an hour,,,,,and it shows!
Quote:
Originally Posted by RVbySDI View Post
Interesting reports of quick build tanks. The amount of work you have already put into these tanks hopefully shows that it would not be that much more difficult for anyone building to build their own tanks.

I recall when I built my tanks I was extremely nervous and concerned about building the tanks. I was concerned about the mess, whether I was adequately mixing the sealant correctly, whether I was using enough/too much sealant. In other words, I had very little confidence in my own abilities. But then, a funny thing happens with confidence.

Once one just dives in and starts doing the thing that frightens us the most, we find out it really wasn't as bad as we had led ourselves to believe it would be. That is exactly what happened to me. Yes, the sealant was messy. Even so, it still wasn't as bad as I convinced myself it would be. Yes, it was a learning experience finding out how just exactly I needed to mix the two part sealant. Yet, when I did it a few times I devised a system that worked for me. I learned how much sealant was enough. I LEARNED! And you know, it really wasn't that bad after all!

It is really interesting to see what you are finding in your pre-built tanks. There will always be times when it might be wise to have someone else do the work for you. In the case of these tanks though, I would say, it really is not all that difficult to do once one gets started. Just go for it and before one realizes it, the task is completed. True there is a lot of new technique to learn, new things to understand, new experiences, but hey that really is one of the important reasons why we are choosing to build our own airplanes. At least that was, and still is, my belief about the building process I undertook.

So, for anyone reading this thread who was thinking they should just buy tanks already built instead of building their own, well, maybe you might reconsider and do the NIKE thing! For those out there old enough to remember JUST DO IT!

"And it wouldn't hurt to stop eating like a pig either!", PRICELESS!!
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #8  
Old 03-03-2018, 08:45 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default Update: 03/03/18

I put 5 hours in today on the tank project. Both filler plugs are finished and ready to install. Removed the second tank vent system. The fitting on this tank was at least fully tightened and flat to the rib, unlike the first. There was even less sealant than the first though. Nothing but a couple drops around where the fitting passes through the rib. Nothing on or around the nut.
I sprayed on some layout blueing on the end of one tank to mark a cut line where the new bay will be added. I tried to flatten one of the screw dimples with the squeezer to see how that worked to give me another 1/8" on the joint flange. It distorted the metal so I abandoned that idea.
[IMG]DSC02050 by David C, on Flickr[/IMG]
I used a 1/4" rubber mat I have been cannibalizing for projects as a straight edge for my mini Dremel saw. I used carpet tape to hold it right on the line. The Dremel saw worked great using an abrasive cut-off wheel, and made a nice straight cut. I cut right to the edge of the screw dimples to give me the widest flange possible for the mending strap.
[IMG]DSC02051 by David C, on Flickr[/IMG]
The cut was clean and straight requiring minimal effort to clean up. Unfortunately even after cutting right to the edge of the screw dimple, it only left me with a 3/8" flange to attach the mending strap.
[IMG]DSC02052 by David C, on Flickr[/IMG]
I used the outside of the tank to pre-bend the mending strap. These come four to a bundle in the "wing trim bundle" from Van's.
[IMG]DSC02053 by David C, on Flickr[/IMG]
Knowing I was not happy with the narrow flange, I went ahead and did a trial run anyway. (Waiting for back-orderd parts). I marked, drilled, and dimpled the tank skin flange and the mending strap.
[IMG]DSC02054 by David C, on Flickr[/IMG]
[IMG]DSC02055 by David C, on Flickr[/IMG]
I want the mending strap centered between the original tank skin and the new bay skin. I am going to re-cut the tank INBOARD of the filler opening, then install a new inner tank rib 2" inboard of the new cut line. This will eliminate the filler opening patch ad give me plenty of tank skin flange material for the mending strap.

To be continued,,,,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018
Reply With Quote
  #9  
Old 03-04-2018, 09:40 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default Update: 03/04/18

I got a solid 7.5 hours working on the tanks today. I am only doing one tank at a time right now. This is the right tank. If I make a mistake its better to be on only one tank.
My first step today was to remove the the outboard end rib. Again, the stripper works magic loosening up the sealant to scrape away and get to the rivets for drilling out. I will also be drilling out a run of skin to baffle rivets extending 2 rivets inboard beyond the new tank skin cut line. This will allow me to slip a .014" piece of stainless steel between the tank skin and baffle to protect it from getting cut by the blade.
[IMG]DSC02059 by David C, on Flickr[/IMG]
Cut and saw guide line layed out. I decided to extend the tank by a total of 13". This will give me an additional 4 gallons per tank.
[IMG]DSC02060 by David C, on Flickr[/IMG]
Here you can see that the Dremel saw with an abrasive cut-off wheel did a great job. I put a 90* bend on the .014" SS baffle to protect the baffle flange and wall. I stopped the cut with the saw right before it hit the baffle and finished the cut with my oscillating multi tool equipped with a half moon BI-Metal blade. I let the blade cut with little pressure and it just skipped over the SS when it made it through the aluminum skin.
DSC02061 by David C, on Flickr
The SS shield in place.
[IMG]DSC02063 by David C, on Flickr[/IMG]
I cleaned it all up and set the new interior baffle in place 2" inboard of the cut line. Put a sharpie line along the 2" recess and used that to center the rib rivet holes on.
[IMG]DSC02064 by David C, on Flickr[/IMG]
The gold colored circles are my finished alodined access hole covers. I matched drilled the rib to the baffle first. There is a .032" strip spacer/filler between the rib flange and access cover. I then match drilled the rib centering the flange holes over the line, clecoing as I drilled working towards the leading edge.
[IMG]DSC02065 by David C, on Flickr[/IMG]
I then marked a center line on my .032" X 1-1/2" wide mending strip. I feel good having a 3/4" overlap on both skins for mending. With the baffle extending out into the new tank bays, this will stitch everything together nicely.
[IMG]DSC02066 by David C, on Flickr[/IMG]

Continued,,,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018

Last edited by 9GT : 03-04-2018 at 10:27 PM.
Reply With Quote
  #10  
Old 03-04-2018, 10:20 PM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,421
Default 03/04/18 continued:

Rib, mending strap, and access cover clecoed in place.
[IMG]DSC02067 by David C, on Flickr[/IMG]
I cut a baffle piece 13" long to butt and splice onto the end of the original tank baffle. You can't beat a high quality miter saw with a fine tooth carbide blade for making accurate cuts in aluminum.
[IMG]DSC02069 by David C, on Flickr[/IMG]
The Z bracket I removed when I took off the end rib will be reinstalled in its original rivet holes when it all gets riveted together, so no problem getting it where it belongs. I will add 2 more Z brackets on the new baffle to mount to the spar also.
[IMG]DSC02070 by David C, on Flickr[/IMG]
I cut a 4.5" wide section of new baffle material to mend the two baffles together. I will also cut out a couple pieces of the baffle flange and wall to make a doubler under the aft baffle flange. I will rivet it to the baffle and baffle mending plate wall first, then match drill using the new tank skin through the baffle flange and the doubler,,, riveting it all together when I get to that point. I will also use the baffle mending plate flange to get a few rivets into the tank skin there also, top and bottom. I am able to get my hand in both sides of the new rib that splits the access hole so I will have no issues getting everything sealed up in those bays.
[IMG]DSC02068 by David C, on Flickr[/IMG]
I can't do much more work until I get the back ordered parts from Van's and I am heading out of town for a week Tuesday. Will post an update when I get back at it.

Too be continued,,,,,
__________________
David C.
Howell, MI

RV-9A: Under Construction. N161RV (Reserved)
RV-10: N959RV Completed 12/29/2013 SOLD 08/23/2016

"Donor Exempt" but donated through Dec. 2018

Last edited by 9GT : 03-04-2018 at 10:32 PM.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 02:40 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.