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PA12 Fuselage Modifications

Steve Pierce

Steve Pierce

BENEFACTOR
Graham, TX
So I have been tasked with the repair of a PA12 fuselage on Wipair amphibious floats. The wings are at another shop and covered. The fuselage needs some repairs in the gear area and the wing attach area and was trying to find out if there were any "Need To" mods while we are here. We would like to add weld on float fittings, call into Charlie Center on his STC, only other one I found were for EDOs. Also would like to do PA18 gear which looks like someone started but no paperwork. I see there are STCs for this from both Sullivan and Borer. Not sure pros and cons of either etc. The other question is would a GW modification be feasible if wings are covered? I see Charlie and Roger Borer have STCs for the GW increase. Any help for an uninformed mechanic on PA12s is greatly appreciated. I do have Charlie's PA12 here right now that was on the cover of Northern Pilot several years ago and have looked at some of the documentation on it and do have a call into him.

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Mine has weld on float fittings and 1935 gross wt that is just adding some tubes at the back end. Don't think the wings are different. I have AOSS and 3 inch extended gear, rear underseat storage and 18 control system. Cathedral and skylight. Right swing up door, underseat battery, side access door for extented baggage. For some reason the guy didn't want flaps----that's about all it's missing.
 
charlie's GW involves lots of welding and added tubes in fuselage... no changes in wings, if i remember right

only thing you add is cabane tabs for gear install
 
180Marty said:
Mine has weld on float fittings and 1935 gross wt that is just adding some tubes at the back end. Don't think the wings are different. I have AOSS and 3 inch extended gear, rear underseat storage and 18 control system. Cathedral and skylight. Right swing up door, underseat battery, side access door for extented baggage. For some reason the guy didn't want flaps----that's about all it's missing.
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Do you know what paperwork they used on float fittings, and GW?
 
Do you know what paperwork they used on float fittings, and GW?
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Crosswinds gross weight----installed 1935 and rear baggage access with STC SA689SL and dwg 1002. Float fittings are Atlee Dodge p/n 3143-12 STC SA00132SE instruction doc # 3143-12-I and 3143-12A
 
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Awesome, thanks guys. Just got off the phone with Charlie and he gave me some great info as well. Will look at Mike's photos and see if the customer wants to spend the money on the GW increase. Didn't realize the Atlee fittings were STC'd on the 12. Looks like Clifford my welder is going to be plenty busy. Thanks again.
 
Steve Pierce said:
..Didn't realize the Atlee fittings were STC'd on the 12. Looks like Clifford my welder is going to be plenty busy. Thanks again.
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Atlee's don't fit a -12 at bottom well.. you will have to be creative welding them on and use BIG filler rod... and don't weld them on the wrong cluster.. i had to move some on a project someone put in wrong location.. not fun...
 
I recommend the GW increase with the float fittings as it would be tough to stay 'legal' once the floats are on, especially with amphibs. On my 12 no wing changes just those fuselage tubes to get it to 1935#, I had both put in by Univair when I had to get a new fuselage, so used whatever STC they recommended (sorry I don't have my books in front of me) but I believe they are Atlee's. My gross weight increase made it difficult to put in a lower baggage door in, or the original battery door so I also recommend moving the battery forward. I put a Odyssey battery under the rear seat via a 337, (currently in for review by the FAA, I can send you a copy when I get it finalized). The float fittings will require the 1" float tube installed from the left front wing fitting to the lift strut bracket at the back of the windshield.

I highly recommend the pa-14 cathedral in the baggage area, Atlee has the STC approved now.

On one of the STC's-I think it was the GW increase, Sullivan and Charlie worked together and both submitted it so it doesn't matter which one you chose, they are the same.

Hopefully here are some pics, there rear door in the rear of the fuselage is where I installed the 406 elt, sorry I couldn't find pics of the battery relocation, I will be near the plane on tuesday if you need them: IMG_2897.JPGIMG_3347 - Copy.JPG0707161033.jpg
 

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Steve, perhaps talk with Charly in person about the cargo door, if you didn't already do so. He hand-wrote on my drawings, "approved for PA-12". Maybe he isn't permitted to do that anymore, but it might be worth the conversation.

Edit: I REALLY like that cargo door, for ease of loading stuff, and because my wife delights in the great visibility. Mine is covered with plexiglass.
 
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A timely thread! PA12 wings show up here next weekend, then fuselage when I'm ready for it. I'm interested in Crosswinds' gross weight increase and skylight. Right now he's got bolted float fittings, but welded has been discussed, along with seaplane door, cathedral ceilings and a few others.

We're starting with: PA-18 front seat, PA-18 torque tube, PA-18 gear and tail feathers, 150hp (Kenmore), Flaps, PA-18 trim, Large baggage, Cleveland wheels and brakes, Ferguson tips, pump down skis, Edo 89-2000's.

John
 
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Hardtailjohn said:
.. Flaps,
John
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if adding flaps, do the Day & night STC for the LONG flaps made out of -18 ailerons(except don't use -18 ailerons, have dakota cub make new ones with proper twist) and just move aileron bay outboard... you can even do this on covered wings with a bit of effort...
 
I just went through a fuselage rebuild on my 12. I cheated and bought a new fuse. The original fuselage had lots of corrosion. I put the very extended baggage back in with large upper extended baggage door. I really like my extended baggage but I think the best plan would be to make the regular big baggage without the extended portion. Then get a belly pod. By the time you add up door and frame, floor and floor substructure and aluminum side panels it is heavier than you would think. Put a belly pod on and you probably get more storage and all that cargo weight is now under you instead of way behind you. Belly pod is 25? pounds and extended baggage is probably 10 (hopefully less).
 
I guess the pod would probably equal the lower portion of the extended baggage. The upper portion would make it bigger than a pod.
 
There are probably some tabs and pulley mounts that could be welded in for flaps that might be really helpful in the future.


Bill
 
Bill Rusk said:
There are probably some tabs and pulley mounts that could be welded in for flaps that might be really helpful in the future.


Bill
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If welding in flap pulley bolts do NOT just do what the stc shows. Add gussets like I show on the mount bolts. I have fixed 3 planes that had the rear bolt fail and rip out of the tubes in flight/final.
 
Steve,

If he is on Wip amphibs he doesn't need a GWI tubes to get the up gross because it is included in the Wip STC.

Unless he wants 1935 on wheels, too, the extra tubes are unnecessary.
 
Paul Heinrich said:
Steve,

If he is on Wip amphibs he doesn't need a GWI tubes to get the up gross because it is included in the Wip STC.

Unless he wants 1935 on wheels, too, the extra tubes are unnecessary.
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Thanks, that is good to know. Wipaire was on my "To Call" list, that is the problem with being tasked with the repair of a component and any mods that might be needed but not having the actual aircraft paperwork. I was given a list of the STCs already installed but was not aware of the GW increase on Wips. Now to figure out some of the tubing changes and the SC elevator, flap installation and trim system modifications and what data was used since we can't find any paperwork on them.
 
mike mcs repair said:
If welding in flap pulley bolts do NOT just do what the stc shows. Add gussets like I show on the mount bolts. I have fixed 3 planes that had the rear bolt fail and rip out of the tubes in flight/final.
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Mike: Just curious ---did these failures result in accidents/incidents or a change of pilots laundry ????---geezer Dan
 
I just looked up the airworthiness on this PA12. All these mods on the frame I am working are not documented but it was imported back into the country from Canada in 2009 and issued a new Airworthiness Certificate so everything that was installed at that time is legal.
 
have you looked at the oversized pa-18 tail feathers from Atlee? they are stc'd for the 12, and only a few bucks more. It seems like the 12 can always use a little more up elevator in the final flair, and i am hoping the larger tailfeathers help there.
 
jrb said:
I just went through a fuselage rebuild on my 12. I cheated and bought a new fuse. The original fuselage had lots of corrosion. I put the very extended baggage back in with large upper extended baggage door. I really like my extended baggage but I think the best plan would be to make the regular big baggage without the extended portion. Then get a belly pod. By the time you add up door and frame, floor and floor substructure and aluminum side panels it is heavier than you would think. Put a belly pod on and you probably get more storage and all that cargo weight is now under you instead of way behind you. Belly pod is 25? pounds and extended baggage is probably 10 (hopefully less).
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Did you buy the Univair fuselage, and if so what did you think? Did you have it built the way you wanted, or did you have to do more welding & fitting after you received it?

Which seaplane door mod did you use?? STC or 337??

Thanks. I'm just getting started now with a rebuild of our PA-12-150. I'd like to keep it flying as long as possible by starting with a new fuse as well.
 
I bought and used a new Unovair fuselage. I love it and they are great to deal with. They put in all of my previously approved mods whether done in the past by STC, field approval or just log book entry, as long as it was documented. A new door came with the frame which fits perfect. They put in a seaplane door as log book had previous approval. I bought a couple stc's for it like gross weight and rear seat bar, again great to deal with and I didn't have to modify it abit once I got it, I only wish I would of had them paint it as well. I also wish I would have had them make the door a cargo door but I thought of that too late, it is shown on the green plane in the first thread. Doug
 
Thank you, Doug.

That sounds cool and is exactly what I plan to do. Placed my order a couple of days ago and Jim told me that I have a month to add any details or more mods that I want. I'm getting all that in order now.
 
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