Leaky Bladders…
February 26, 2016
If you haven’t heard, probably the least loved task to do on a Cessna Skywagon is replacing bladders. Fortunately for me, I was happily tapped by fate to take this dive after springing a leak.
Since I started on the resto of the Wagon, I knew that I was going to have to face this at some point, but have been pushing and pushing it off until finally my number was up.
My 66 has extended tanks, which is both a blessing and a curse. Curse because the tank is bigger. Blessing because there are two ports to allow just a bit better access.
First step is pull the bung and drain all the fuel. (This is a great time to order new sump drain valves and stainless steel safety wire screws)
Next, pull the ports and caps. Also a good idea to order new stainless fasteners here as well. On my airplane, the large machine screws are MS24694C48, the small ones are MS24693C293, and the stainless safety wire screws for the drain are AN500AD8-7.
Be very careful removing the screws as chances are they are in there good and solid. Get some penetrating oil on and let them soak overnight. Use the CORRECT screwdriver, and take your time.
If your unlucky enough to round out the well, don’t fret as you can use a Dremel and cutoff wheel to carefully make a slot in the head for a regular screwdriver. Takes practice, but doable without getting into the surrounding alum. (Just make sure there are no vapors kicking around!)
With the caps out, a good idea is to line the edges of the cavity with duct tape to protect both the tank AND your arms. You will thank me later…
With the caps out, take your time and remove all fittings. This will be fuel outlet screens (forward and aft in later models) crossover vent, fuel sump, fuel sending unit, and outboard vent.
The fuel outlets are the trickiest because they are delicate. Once out, it’s a good time to give em a real good inspection. Although not always possible, I am a big fan of replacing parts with new. The problem with these screens is (like everything) Cessna wants an ungodly chunk of change… Have a late mode bird and you have now doubled that ass raping cuz you need two.
The good news is that Burl’s Aircraft in AK has a fantastic solution. Their STC’d spun aluminum screens are not only cheaper, but they provide a much better flow rate. Worth checking out!
Anyway… reach in the cavity and roll the bladder into a nice tight sausage, and then CAREFULLY work it out the port. This part sucks for sure, but enjoy it cuz getting her back in will make this part feel like cotton candy and prancing unicorns.
With the tank out, get her in a box and ship her out. There are two big places to send out the bladder. Although their website is cerca 1990, I have had great luck with the service from Heartwig. Eric is a good dude and worth a phone call.
If you weren’t having fun yet, strap it on…
Lots of AP’s lazy-out here because when it comes down to it (you know who you are,) it’s really tough to send the customer a bill for all the time it actually takes to clean and prep a tank bay. But if you want it done right, make sure you take your time and get it clean enough to eat off. (Took me 9 hrs of labor to remove tape & clean.)
Start by pulling the old tape that you can grab. Heating it up with a heat gun makes this a bit easier and if your lucky, you will be able to get most out without falling into small strips.
Once the tape is off, you will be left with the dried glue. I find that the best solvent to get this stuff off is called “Goof Off.” Stuff works fantastic, but a real killer… so make sure you have good gloves and a solid respirator.
Now that you have cleaned the bay, you can start laying in the new tape. The point of the tape is to protect the bladder from chafing on corners and rivet heads. Some think that you can just use Duct tape, but this is not the case. Tell Eric at Heartwig you need a roll, and he will provide you with one on return of the bladder.
Laying the new tape in perfectly is next to impossible, so don’t get too bent if it isn’t 100% pretty. Just take your time, and do your best. If you did a kick ass job with the prep, the tape will hold solid for another decade and the next guy wont shake his head at you when he gets back in here.
Sometimes they are too far gone, but with some luck, Heartwig will be able to repair the bladders. They will come nice and shiny and oiled. If you can, put the bladder in a heated room overnight to get it nice and playable. You will also want to crank the heat in the hanger.
Lay out the bladder, roll it up into a sausage again, and start sliding it in.
Once in, lay it flat and start asking Job for patience. First, connect the snaps (bottom of the tank) to their position in the corners. Once you have these, patiently work the top fittings, getting the furthest ones first. Ain’t gonna candy coat it… this really blows.
Truth be told, this isn’t the hardest thing to do, but there is no doubt that this is the most trying task one can undertake. All I can say is know it can be done. You don’t need to take the damn wing off, remove any ribs or skins… Just take your time, don’t get frustrated, and motor thru. Oh… and if you have short arms your F’d.
With the bladder in and all the snaps fitted, go ahead and reconnect all the plumbing, caps, and sending units. Make sure you use NEW gaskets! If you are really progressive, you might think about installing new McFarlane fuel sending units here, but I guess I should remember how easy it is for me to spend your money on the interweb.
If you don’t have a good torq wrench, make sure you pick one up. It’s always critical, but here, an overzealous wrist can cause a leak pretty fast… And that blows.
At any rate, that’s a quickie on Wagon bladders. Good luck!