Archive for category Fuel Tanks
Right Tank Leak Test Take 2 and Back to the Leading Edges (11/25/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Leading Edges, Wings on November 25, 2010
1.5 Hours -
Its Thanksgiving Day, and I had a little time to work on the plane before we head to my parents for dinner.
I started off the morning, by retesting the right fuel tank for leaks. I really didn’t have very high hopes for the quick fix on this tank, but it was worth a shot. Unfortunately, the quick fix made the leaks even worse. Instead of leaking at the baffle/skin seam, the sealant filets just redirected the leaks so that the air now comes out of the skin/baffle rivet row.
Since the right tank still leaks, I’ll go ahead and do the major fix that is recommended by many builders. To do this, I’ll cut 3″ holes in the baffle using a hole saw. I’ll have to cut one hole in each bay of the tank, then reach in and reapply sealant to the inside of the skin baffle joint. I’ll put it on very heavy this time. Once the new sealant filet is in, I’ll cover the holes with 4″ diameter pieces of aluminum and some closed end pop-rivets (which I already ordered, since I didn’t think my first fix would work anyway).
Once I finished the leak test on the right tank, I removed the right leading edge from the wing and started to disassemble it for final prep. The only part I managed to finish was the joint strip. I had to drill the strip for nutplates, then deburr, dimple and prime the strip. Finally, I riveted the nutplates in place using some 3-3.5 “oops” rivets.
I used the actual nutplates as guides for drilling the joint strip.
Here the joint strip has been primed, and all the nutplates are attached.
I used oops rivets to rivet the nutplates to the joint strip.
Left Tank Closed (11/22/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 22, 2010
1.0 Hours -
Most of the time spent working on the plane this evening was used to clean up my clecos. Some of them were getting quite a build-up of sealant, so I soaked them in MEK overnight, and then wiped off as much as the sealant as I could. Most of it came off fairly easily, and what’s left won’t really affect their function. At least they look better now.
After playing with the clecos, I mixed up a small batch of sealant, and used it to seal on the tank access cover and fuel level sender. As with the right tank, I’ve opted to toss out the gaskets supplied with these and just use sealant. I’m also using the supplied screws rather than “upgrading” to stainless steel screws that use allen wrenches.
I’ll wait about a week before testing the left tank and retesting the right. Hopefully, there will be no leaks present…in the meantime, I’ll move on to the leading edges.
Left Tank Baffle Riveted (11/21/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 21, 2010
3.0 Hours -
Although it feels like I’ve been working on these fuel tanks forever, the end is in sight. Closing the left tank definitely felt like a milestone!
I started the day by deburring the edges of the left tank baffle. This was pretty easy and only took a quick pass on the Scotchbrite wheel. After the deburring, I thoroughly cleaned the baffle with MEK and then prepared a batch of tank sealant.
As with the right tank, I used about 110 grams of sealant for the baffle. However, for this tank, I used a little more sealant for the skin/baffle joint, and I placed the bead of sealant over the rivet line instead of on the forward edge of the rivets. Hopefully, this will prevent the leaks that occurred on the right tank (I still need to retest the right tank as well).
Once all the sealant was in place, I lowered the baffle, lined up all the holes, and then clecoed everything together. To rivet the baffle, I started by squeezing all of the skin to baffle rivets, then I installed the rivets and z-brackets for the outboard and inboard ribs, then I installed all the pop rivets and z-brackets for the interior ribs. For some reason, the pop rivets seemed much more difficult to install this time around. Oh well, they all went in eventually!
Sealed and clecoed, the left tank baffle is ready to rivet.
Another view of the left tank baffle.
Finally, I cleaned up the tank a bit, and then mixed up another small batch of sealant just to do some touch-up work. I could have used the sealant that I had left from the first batch, but it was starting to get a little rubbery and difficult to work with.
Once everything was finished and cleaned, I sat the tank vertically on the bench with the baffle/z-brackets facing down. It probably won’t do anything, but maybe gravity will help ensure that the skin to baffle bead of sealant is constant.
The key parts of this picture are that the z-brackets are on and the tank is finally out of the cradle.
Hopefully, I’m almost done with the tanks and working with sealant. In another week, I’ll test the left tank and retest the right. With any luck, my fuel tank building days will be behind me and I can, finally, move on to something else!
Soaking my clecos in MEK for awhile should make it easier to clean the sealant off of them.
Left Inboard Tank Rib Riveted (11/20/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 20, 2010
2.2 Hours -
Even though I can squeeze the rivets attaching the inboard rib to the tank skin, it takes longer to attach the outer ribs, compared to the inboard ribs, since the reinforcement plate and bracket also have to be attached. However, this rib, along with the plate and bracket, seemed easier to assemble than on the right tank.
Now that the left inboard rib is in, I only have to attach the baffle and I'll be done with the left tank.
Once the rib, plate, and bracket were all riveted in place, I went ahead and attached the vent line fittings to the rib and connected the vent line. In retrospect, I should have waited until tomorrow to do this because I ended up getting sealant everywhere. If I had allowed the sealant on the rib to set overnight, this would have been a lot less messy!
The internal connection of the vent line. Not much to see after it is smothered is goop...I mean sealant.
Test Fit Left Fuel Sender, Float, and Vent Line (11/17/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 17, 2010
0.4 Hours -
I feel like I’ve been neglecting the airplane project for the last couple of weeks, so I spent a little time this evening working on the final touches that need to be completed in the left fuel tank prior to closing it.
First, I test fit the tank access panel and fuel level sender in the tank. This was done mainly to make sure that the bend I made in the fuel float wire was correct and provided the necessary range of motion for the fuel level sender. In addition to checking the range of motion, which was good, I also performed one more electrical check to make sure the sender was actually sending!
I temporarily installed the access plate and fuel sender to check my bend on the fuel float. The empty position is barely touching the bottom of the tank.
The full position is just shy of the top of the tank. I'm more concerned with accurate readings at empty than at full.
With the fuel level sender situated, I removed the inboard rib, and inserted the vent line as well as the snap bushings that hold it in place. Once the vent line was in the tank, I reinstalled the inboard rib and attached the vent line using the appropriate hardware. The fit and length of the vent line was perfect. The only adjustment I made was to give the outboard end of the line a slight, upward bend, ensuring it was in the high-point of the tank.
The vent line installed in the vent clip.
The inboard end of the vent line test fit to the inboard rib.
The left tank is now ready to have the inboard rib and baffle installed.
Only One Rib Left In the Left Tank (11/14/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 14, 2010
3.2 Hours -
Earlier in the week, I received my second quart of tank sealant from Van’s. However, I didn’t have any time to work on the plane until this weekend. With a new batch of sealant, I’ll have way more than I need to finish the tanks…at least it is relatively cheap stuff.
My new batch of sealant arrived earlier in the week...I'm gonna have a lot left over now!
I pretty much have a system down for riveting the tank ribs to the skin. It is now taking me around 40 minutes per rib with almost no bad rivets. The last two inner tank ribs were easy to rivet, and I then moved on to working on some of the finishing touches that must be completed before closing the tank.
Since I’m using the pre-fabbed fuel pick-ups from Van’s, the only thing I have to do is test fit the pick-up to make sure it sits in the correct place in the tank. Once I had it oriented correctly, I went ahead and installed the pick-up on the tank access panel using the appropriate AN hardware, anti-rotation bracket and sealant.
I had to make sure the pre-fabbed fuel pick-up fit properly before attaching it permanently.
Here, the fuel pick-up is attached and sealed.
I also put some sealant on the outside of the pick-up...why not, I have a whole lot of sealant now!
Finally, I pulled out the fuel level sending unit for the left tank and bent the float wire. This one went much more quickly than the right float. Of course, when you are using a mallet and a vise as your primary tools, it is difficult to go slow. However, I still have to test fit the sending unit to make sure the float reaches the top and bottom of the tank.
Bending the fuel float wire seemed much easier this time around.
Two More Ribs In Left Tank (11/7/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 7, 2010
1.8 Hours -
I really wanted to work on the plane longer today, but after riveting two more ribs into the left tank, I was out of sealant. Fortunately, I placed an order from Van’s for more sealant earlier in the week and it should be here by Wednesday.
Two more ribs riveted...three to go!
Outboard Rib Riveted In Left Tank (11/3/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 3, 2010
1.5 Hours -
I didn’t really feel like banging away with the rivet gun tonight, but I still wanted to get an hour or two of work in on the plane. So, I decided to rivet the outboard rib on the left tank since it’s rivets could be squeezed instead of bucked.
Five more ribs to go…
First Rib Riveted in Left Tank (11/2/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on November 2, 2010
1.9 Hours -
I had just about forgotten how much fun it was to rivet ribs coated in sealant (sarcasm)!
The ribs for the left tank still needed to be scuffed and cleaned, so I started the evening by doing those tasks. It is a good thing that I always take a close look at my parts during this stage or at some point right before final assembly…I had managed to miss three holes in one rib when I did my dimpling. At least this is a quick fix, as all I had to do was pull out my squeezer, turn on the air, and pull the trigger three times.
Once everything was scuffed and thoroughly cleaned, I clecoed the ribs into the tank skin.
After scuffing and cleaning the ribs, I clecoed the left tank back together.
After the tank was assembled, I removed the second most outboard rib and then mixed a batch of sealant. At this point, I’m starting to run low on sealant. I may have enough to finish the tank, but it will take a lot of scraping of the can. I’ll go ahead and order another quart kit from Van’s to make sure I have more than enough. Since I may still have leaks to fix in the right tank, and who knows on the left, I’m better off having plenty of sealant on hand.
Once my 44 grams of sealant was well mixed, I spread some on the rib flange and reinserted the rib with clecos in every hole. I then removed the outboard rib to allow better access for riveting.
Finally, I riveted the rib working from forward to aft, one side at a time. After riveting, I did some clean-up on the tank and my tools, but I really didn’t make much of a mess this time…I even managed to keep my gloves clean.
Once the factory heads are cleaned up, the rivet line looks pretty nice.
The sealant filet on the inboard side of the rib.
The sealant filet and rivet encapsulation on the outboard side of the rib.
One rib down, six more to go.
Right Tank Tested; Left Tank Riveting Started (10/31/10)
Posted by Ethan Jacoby in Construction, Fuel Tanks, Wings on October 31, 2010
2.5 Hours -
Its finally time to test my first fuel tank for leaks. I have one of the fuel tank test kits form Van’s, which consists of a cap for the fuel pickup line and a inflation stem that screws into the tank drain flange. After the pickup line and drain are plugged, a balloon is placed over the vent line fitting to act as pressure relief for the tank and give a visual indicator of air pressure.
Once everything was ready, I sprayed the tank down with some soapy water and then started pumping air into the tank. All of the rib and stiffener rivets checked out fine, as did the fuel cap and drain. However, I found four small leaks on the baffle to skin joint. After cleaning up the tank, I made my first attempt to fix these leaks by smearing some sealant on the outside of the joint. I’m hoping this is all it takes since the next step may be to cut access holes in the baffle. Because all of the leaks are in the baffle/skin joint, I’m also going to change the way I seal the baffle when I get to this stage on the left tank.
The right tank had four leaks in it...all in the baffle to skin joint.
To fix the leaks, I tried spreading some sealant over the baffle/skin joint. Since the leaks are small, I'm hoping this will be all that is needed.
After testing and, hopefully, fixing the right tank, I started to work on the left tank again. I thoroughly cleaned the tank, stiffeners, fuel cap flange, fuel drain flange, and a bunch of rivets with MEK. Then, I taped all of the stiffener rivets into place, mixed up some more sealant, and back-riveted the stiffeners to the skin. After each stiffener was riveted, I made sure it had a solid filet of sealant around the edges and then encapsulated the shop heads in sealant.
I cleaned the left tank skin and stiffeners with MEK before riveting.
The left tank stiffeners have been back-riveted to the skin.
Once the stiffeners were done, I went ahead and riveted the fuel cap flange in place. This flange can also be back-riveted, and I even remembered to place the vent line clip on the correct side of the flange this time!
The inside of the fuel cap flange...riveted and sealed. This time, I place the vent line clip on the correct side!
The top of the left fuel cap flange.
Finally, I used my squeezer to set the rivets for the drain flange and then cleaned up the outside of the tank.
I made sure to leave paths for water to reach the drain when I encapsulated the drain flange rivets.
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