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Just a -12 recover.... uhhh nope

rsrguy3

FRIEND
Really got into this over the last few weeks. Supposed to just be a recover, but oratex needs proper paint in order to use the glue... so off to the haboob...
It was a ceconite dope finish, it was a seriously sweet looking 25 footer.
There was corrosion(rust) under the paint. Whoever did it last shot it with epoxy primer(fairlycertain). Epoxy primer is good it just needs to be top coated with urethane... it wasn't topped. Anyway the epoxy is porous and it allows moisture to effect the tubes... not good, I need to replace a few more tubes.
 

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Managed to get the tail done last week. Pulled the cabin down this week and masked for blast and paint next. Pics were taken before I cut the bungees and removed the rear floor.
The headliner was installed using lacing cord.... no headliner bows... no joke.
 

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It is some extra work but if you take the time to hang and rig the wings/tail/thrustline now you will find any major alignment issues that need fixing. Easy to do without the fabric on.
DENNY
 
It is some extra work but if you take the time to hang and rig the wings/tail/thrustline now you will find any major alignment issues that need fixing. Easy to do without the fabric on.
DENNY

Can you expand on this comment? I bought wings from a PA12 to use on my J5 and have not covered them yet.


Sent from my iPhone using Tapatalk
 
I agree, put on the wings and tail surfaces and rig all cables to check for length, rubbing etc, well worth your time, some things are a bugger to fix once the fabric goes on. this also gives you a good chance for an unobstructed view of how the fuel lines should be placed
 
Basically Build the entire plane without fabric. Wings/tail/fuel lines/seats/seat belts/engine/cowling/prop/gear/panel with instruments/ELT. Put it all together and rig all the cables etc. Carefully measure and fully rig the plane. If something is wrong and need adjusting (wing fitting off)it is dirt simple. Then take everything out and paint/fabric. It really sucks to have that one simple change make you cut 3 inspection holes for that extra part or cable run you need. Use bedsheet clamped over fuselage to make sure everything will clear the fabric.
DENNY
 
Help me get my head around this... is there a better way? It doesn't look stock.
 

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Some of the early -12s had a header tank in the left cowl, like the one you showed in the pictures. Here is a parts diagram showing just that.
Later -12s eliminated the header and had a separate valve for left and right tanks.
20240104_121039.jpg
 

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Ok... is there a better way? I have a dakota valve but that doesn't seem like anything that would eliminate this mess.
 
Ok... is there a better way? I have a dakota valve but that doesn't seem like anything that would eliminate this mess.
That's a header tank for nose low fuel flow when there is only a rear outlet in the left tank. Unless you also have a front tank outlet...leave it there.
 
Rsrguy,

The above statements are all true. Let me expand on this a little:

Early PA-12s had the front header tank mounted vertically just you show in the above picture. I think what you have is stock.

Sometime in 1947, they eliminated the header tank and this caused issues with fuel tank unporting with low fuel in a nose low attitude during landing. They only had fuel feed lines from the rear of the tank.

In 1948, when they came out with the PA-14 Family Cruiser, they ran a fuel line from the forward side of the left tank (but not the right tank). This helped with the problem of fuel unporting.

During rebuild, you have the choice of original tanks (they are junk in my opinion), Univair, Dakota Cub or Atlee Dodge. I strongly recommend not using the original ternplate tanks. They are just too old and prone to leaks. Also, the sight gauge hanging below the wing is just a pain. If you go with a different tank ( I recommend Dakota Cub), you can still get rid of the header tanks and use PA-18 wing root sight gauges (again I recommend Dakota). So, Dakota valve, Dakota Tanks and Dakota Sight Gauges. All good quality stuff and approved for the -12. It’s all approved via STC for the -12 but the install diagrams are for the -18 which leaves room for some interpretation.

Here is a picture of how to plumb it on an -18 but yours will be the same.

63009621616__08FA1581-60B8-4469-BF18-2C3D3F34F9ED.jpg

The vent line between the left and right tank runs across the forward spar carry thru. Unfortunately I don’t have a good picture of that. You will need to call Airframes AK or Dakota and get the bracket for the fuel valve to weld to the fuselage. Make sure it tips forward when you weld it on so all the fuel runs downhill.

Hope this helps with some ideas.
 

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It all helps.. the vents both are plumbed (right and left) down from the carry through to the top of the header tank... which puts the rest of the plumbing as per the parts manual. The tanks are the larger fatley dodge ones. Did this left right header tank configuration do the fuel starvation, unport thing? I'm trying to determine if it's a worthwhile effort to pitch an upgrade on the fuel system based on the idea that he has a potential for issues? I'd rather just stab our new dakota valve in and call it good.
 
Ok. Atlee Dodge big 30 gal tanks will do. Use the Atlee Tube sight gauges. Maybe call and ask Atlee if they have some install instructions for those tanks. In lieu of any instructions, plumb fore and aft lines to the Dakota Valve and get rid of the header tank. The header tanks never had a problem unporting. Also, I’ve never heard of a problems as long as you have both front and rear lines out of the tanks.
 
I agree with KJC. fore and aft pick ups in both tanks and dakota valve and you are golden. I plumbed in dakota guages as well but just as isolated guages, just into the tanks, not into any of the lines like are shown on the dakota drawings and they've worked fine in the 2 12s I've done.
 
KJC, any reason you plumbed in a flex line and beaded ends on the outlet of the fuel valve line to the gascolator mid way down the run near your left foot? Just easier install?
 
Yes I agree. My guess is this was done during the ground loop repair.... (pic)I'd also agree that a zip tie in place of a properly repaired oil cooler bracket also isn't as resilient... although I'm sure it's a pma tso tie as it was signed off at annual and made the trip here from its home base.... the generator bracket also was busted up... I don't know the circumstances surrounding the annual but I do know the airplane was not flown enough for this to have happened since the last annual. The filth and hours add up to an incomplete inspection.



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I don't know the circumstances surrounding the annual but I do know the airplane was not flown enough for this to have happened since the last annual. The filth and hours add up to an incomplete inspection.
I assume the plane was flown to you in order to do the work you are doing? These days, since the FAA has outsourced and shirked their duties to issue ferry permits, it is much more convenient to perform an annual with the understanding that it will be a short flight to a facility where major work is to be done. Sometimes you do what you gotta do to get things done. You didn't hear this from me.
 
Finished attaching the skin... with bench fixtured wash.


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They use to be water jetted but we have switched to laser. PA12 kit is a little more because of the number of grommets. If you are not using the jury strut fairings I can adjust the price.
 
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