Looking for advice for PA-12 newbie

[Kwatro]

I am a new member to SuperCub, and am looking for advice. I am purchasing a PA-12, and plan on recovering it right afterwards. I have looked over most of the PA-12 posts on here regarding mods, but what I am looking for is advice as to what mods I need to do now (at the recover), or might regret not doing them later.

It is fairly stock, with a low time O-235 by a known shop. Stock wing, tail, and gear, but has sealed struts and the Scott tailwheel. My plan is to keep the O-235 for now, and will use the plane as a "fun" plane, and hopefully to teach my daughters how to fly. Here is what my research leads me to think:

1) Float Fittings- might as well install them now at recover?

2) PA-18 horizontal stab and elevators. I don't think I need them now with the O-235, but might as well install them at recover? If so, is there an STC to install them without doing the engine mod? I can only find the Kenmore STC to do it all. Would you purchase new from Univair, or try to find used?

3) PA-18 trim system. Seems to be highly recommended, so do it now?

4) PA-18 gear. Since I don't really need it now, this could be done later without major fabric rework?

5) Flaps- since I am not building a working airplane, my thoughts are to stay "no flaps". But will I regret that since I am doing a recover now?

6) Extended baggage mods- I admit to a little confusion on this, since I don't know if this is "internal" modification, or would need fabric mods.


What other issues should be considerd during recover? Again, what I am trying to pin down is not necessarily what mods are needed (ever), just what mods are needed now at the recover. Does that make sense?

Kwatro

 

[behindpropellers]

Kwatro-

The most economical way to get the PA-12 that you are describing is to buy one with the mods already done.

Tim

 

[Kwatro]

Tim- I agree entirely about the economics side of it! Part of this PA-12 project for me is going to be the fun/experience of the recover or rebuild. I am fortunate to have a very experienced IA on the payroll who will be lead on the project, with me providing the cheap labor! Luckily I own a Stearman that I can fly in the interim.

Kwatro

 

[pa12drvr]

"5) Flaps- since I am not building a working airplane, my thoughts are to stay "no flaps". But will I regret that since I am doing a recover now?"

Yes.

Strongly recommend doing the flaps now. You don't have to use them if you don't want to

 

[MaxMotoring]

Kwatro,

If you install the PA-18 tail you will need the PA-18 trim system. The original one does not have the muscle to move the bigger tail at cruise speeds, more considering a future engine upgrade (why install the PA-18 tail then?).

I agree on the flaps issue,

Regards

Maximo

PD read my PA-12 refurbish experience on the August 2009 issue of The Aviation Consumer.

 

[StewartB]

I say you're approaching it backwards. Figure out what your ideal PA-12 is. Identify all the costs of getting your current plane to that standard. If the cost exceeds your comfort zone start value engineering it by cutting the least important improvements. Remember what those are because before you're finished you'll probably find that you're so upside down you may as well do those too.

As they say....been there, done that.

Stewart

 

[Paul Heinrich]

First, sell your stock/no flap wings and buy a new set of pa-14 wings with flaps from Univair. For all the time, aggravation, and expense you will spend trying to figure out how to put flaps on the 60 year old pa-12 wings, you could be off flying with a new set.

Do the 18 trim system and, unless you plan on going back and forth on floats every year, forget the 18 gear.

Weld-on float fittings are nice but you better be damn sure that the fuselage is square and that they are located precisely. Otherwise you will never get the float rigging attached to the plane.

And if your going to do all the things you really should do to a 12, like the extended baggage, sky-light, door post, gross weight increase, tail reinforcement, swing up doors on both sides, and headerless fuel system, you might as will buy a new fuselage from Univair that has all the mods already done to it.

If you have an IA on "the" payroll, you probably can afford to do it right and have it built by one of the experts on this site.

 

[danfena]

Will the fabric pass inspection for a couple more years?? If so, fly it, as is for at least a year. Then see what mods are important to you.

If your daughters are old enough to start lessons now, you wont feel so bad if a groud loop happens with old fabric.

 

[kevin]

I will try to answer your questions the best I can when it comes to a -12

1. Are you going to sell this airplane in the future or do you live in an area where float flying is common? If yes to these, then put float fittings on them. They will bring the value up. If you do put float fittings on, I would install the left side door post tube for strenth. I would also install the fittings for -18 gear. This is a more desireable gear for float flying as it is easier to take the gear on and off. If you are not going to sell in the future or you live in a desert, don't bother with float fittings. They will just add weight.

2.If you are going to keep the O 235, I would not install the -18 or -22 tailfeathers. A stock cub flies just fine with the original tailfeathers. Elevator authority is fine in flare with a stock motor. You can always install the -18 elevators/horizontals at a later date if/when you go up in engine size. There is an STC for this. I can't remember who has it off hand but you can easliy find it by calling Crosswinds STOL or Cub Club or do an FAA search under the TC. I would probably buy new unless I found a perfect used set. Chances are, if you buy a set of used horizontals, the mounting holes will be wallowed out and there is a good chance that the leading edges will be dinged from rocks from landing off field. By the time you find a set, have any repairs made, you are probably better off to buy new.

3. Trim system is highly reccomended. I would do it now. The stock trim WILL slip even with an O-235. If you are going to a bigger engine, you will definataly want this trim. Better to do it now than later if you do an engine swap.

4. PA-18 gear: If you are a float plane, I would put the gear on. Much easier to take the -18 gear on and off than a -12 gear becuase of the external bungees. As mentioned above, I would install the tabs for the -18 cabane so you can go to an -18 gear at a later time if you want to. Consequently, you will add extra weight. I didn't do this because I didn't know EXACTLY where to weld the cabane ears to on my frame and I didn't have a guy that REALLY knew Cubs close by to do this for me.

5. What are you going to do with the airplane. If you are going to use it to teach your kids to fly and go for a burger after church on Sundays and fly off of 2500' pavement, you don't need flaps. These airplanes were made to slip and do so very well. If you are going to be flying in and out of 300' strips all the time, I would put the flaps on.

6. There is an STC for the extended baggage mod. I think Ron Sullivan holds it. If you are not going to sleep in it and not going to put wing covers in it while you are flying, I don't think you need to go 6' back. The most I would go is to the first section behind the seat and not install the dogleg(similar to a stock SC baggage compartment). This mod will lead to another mod: you will have to use an STC to convert to an -18 elevator control system. The extended baggage will be in the way of the original elevator control horn behind the back seat. If you go all the way back, you will want the external doors installed so you can get to your stuff. This adds weight too.

In my opinion, the weak spot on a PA-12 is the trim system and the fuel system. I would definatley install the PA-18 trim system. The fuel tanks were known to leak and collect water. I would replace the fuel tanks with new model tanks, get rid of the head knocker fuel gauges, and install sight gauges in the wing root. Dakota Cub has an STC for this. I would also go to the CC fuel system so you will have forward pickups on the tanks. The original -12 tanks had rear fuel pick ups only and supposedly you could unport the fuel lines when low on fuel descending from altitude.

With all of this being said, I think the biggest think to ask yourself is what is your objective with this plane. This will tell you what kind of mods you will want or not want. I have heard a lot of people say that they have extensive rust on their frames and the frames are just plain hammered. If that is the case, it might be better to just get a new frame as others here have suggested. The sky is the limit with these things and the mods can add up.....FAST!!!

All information is in my humble opinon only. Good Luck.

 

[COFlyer]

Kevin is right about the fuel tanks. They're spot welded stainless steel and soldered to seal the joints. The solder will crack in time and start to seep. They also WILL unport when the tanks get low and the airplane is pitched down for descent. If you stay with the old tanks, keep this in mind.

As the others have said, go with the PA-18 trim system.

If you happen to have the old style gear with the flat diagonal strap, either modify it or get the gear with the streamline diagonal tube. The flat strap gear doesn't take much of a side load and will buckle under in a groundloop or during a turn if the aircraft is operated on skis.

Go with Clevelands if you have the old expander tube brakes.

Do not go by the picture in the PA-12 parts list showing the elevator trim yoke. It is shown upside down. Verify that the yoke is installed properly before you put the cover on- I learned this the hard way.

There are some rectangular plates on the bottom inboard portion of the wing that provides access to the aileron cables. These are in the propwash and vibrate enough to work loose. I made up some supports out of light alum that attach and span between the adjacent ribs so the plates had something solid to screw onto.

Do everything you can to keep the airplane light- it's far too easy to add more and more weight. The best flying airplanes of any one model and H.P are the ones with the lightest E.W.

The PA-12 has enough rudder to do nice slips- it's a fun airplane to fly.

Good luck- have fun.

Tom

 

[Kwatro]

Kevin & Tom (COFlyer)- thanks for the great response...that was exactly what I was looking for. I live in the DFW, Texas area....so there are no float or ski considerations! I plan on keeping it for at least 10+ years, and am buying it to learn how to recover......to teach my college aged daughters how to fly.....and to give rides. It won't be a working airplane! Because of all of the great advice , I have decided....

Float fittings....no
I am keeping the 0-235, so I will do the tail feathers later if I change engines
PA-18 trim.....yes
PA-18 gear....no
Fuel tanks.....I will take your advice and install new tanks with wing root guages now, with the money I save from not doing the other stuff.

Thanks again for the detailed advice.

Kwatro

 

[mike mcs repair]

Kevin & Tom (COFlyer)- thanks for the great response...that was exactly what I was looking for. I live in the DFW, Texas area....so there are no float or ski considerations! I plan on keeping it for at least 10+ years, and am buying it to learn how to recover......to teach my college aged daughters how to fly.....and to give rides. It won't be a working airplane! Because of all of the great advice , I have decided....

Float fittings....no
I am keeping the 0-235, so I will do the tail feathers later if I change engines
PA-18 trim.....yes
PA-18 gear....no
Fuel tanks.....I will take your advice and install new tanks with wing root guages now, with the money I save from not doing the other stuff.

Thanks again for the detailed advice.

Kwatro

might weld on the little -18 gear fitting adaptor plates now, i think they won't interfere with the -12 gear... but someone else needs to verify that, don't have the old 12 gear here anymore to make sure a gusset or such won't hit...

 

[Gordon Misch]

I tried it and it did interfere - but that might well have been specific to my situation.

 

[mike mcs repair]

I tried it and it did interfere - but that might well have been specific to my situation.

you are probably right, something reminds me that there is a gusset or something in the corner of the gear there....

 

[COFlyer]

Kwatro,

Here's a few more thoughts on your rebuild/recover:

The PA-12 originally had 1280 bungee cords. Most places sell the 1280HD's (heavy duty). Being that you're not going to haul large amounts of moose meat around, you'll want to get hold of the straight 1280's so the gear won't be too stiff. I got some from Univair.

Piper used aluminum tubing as an electrical conductor between the starter relay and the starter. This is lightweight and alum, by itself, is a good conductor. The problem is that alum forms an oxide insulating coating on its' surface and will make high resistance joints. Mine had arc and burn marks. You either might want to use the "no-ox" paste that electricians use or just replace the tubes with a good quality copper wire, if it's not been replaced already. There's also an AD to route the starter cable up over the bungee trunnion- you should see this on the right hand side of the floorboards.

Check the cast alum aileron bellcranks for cracks. There's an AD on this also, but they're difficult to inspect with the wing covered- one of mine was cracked. The bolts don't need to be tightened down hard, only snug.

Double up on the upper leading edge skin ahead of the fuel filler neck. The handles of fuel nozzles hit this point and it just needs a little more beef.

The lower longeron tubes are bowed out slightly- this is the way the factory set them. This way, when the fabric tightens, it will pull them close to straight.

Read the threads on the fuel valves- they need to be lubricated periodically or replaced with one of the new types.

The instrument panel is tilted forward which doesn't work quite as well for gyro instruments which are set for a vertical panel. My art. horz. works ok but the horizon adj. is out of range. Just so you are aware.

The cowling has some support tubes added, per an old AD, to keep the cowl from raising up in flight. The nosebowl will rub on the engine starter ring gear, otherwise. I also think the the "fit" of the cowl, as a whole, also wants to raise up the nosebowl. Most PA-12's have cracks in the upper aft corners of the cowl door- I think this is caused by stress from the misfitted cowls. As the mount rubbers age, the engine droops and everything just gets worse. You might want to spend a little time shimming the lower cowl support channels to get the cowl to fit properly without being "prestressed". Also, checkout the threads on the "thrustline" mod.

Get rid of the leaky old glass gascolator and get Steve's- http://www.stevesaircraft.com/gascolator.php

The PA-12 should be an excellent trainer for your girls. Stalls with one person on board is kind off a non-event but, like the rest of the flight characteristics, are straightforward, honest, and predictable.

Tom

 

[N2344M]

If you're going to have the fabric off of it, might as well install a Gross Weight Increase to 1,935 lbs....

 

[cruiser]

Those "ears" on the aileron bellcranks crack because the thin washers on either side of the rod ends are left out. Detailed in the SB. The washers can be added easily but replacing the bellcrank with fabric on will require a small hole and dollar patch. Jim

 

[Scooter7779h]

[quote/] MCS Mike Skup wrote

might weld on the little -18 gear fitting adaptor plates now, i think they won't interfere with the -12 gear... but someone else needs to verify that, don't have the old 12 gear here anymore to make sure a gusset or such won't hit...[/quote]

I am certain that PA-12 gear will not be interfered with by having the -18 gear tabs on. Not from my -12 experience as it has had -18 gear on it since the 60's but a friend of mine did the -18 gear mod, and added the actual gear and cabanve later.

 

[mike mcs repair]

MCS Mike Skup wrote

might weld on the little -18 gear fitting adaptor plates now, i think they won't interfere with the -12 gear... but someone else needs to verify that, don't have the old 12 gear here anymore to make sure a gusset or such won't hit...

I am certain that PA-12 gear will not be interfered with by having the -18 gear tabs on. Not from my -12 experience as it has had -18 gear on it since the 60's but a friend of mine did the -18 gear mod, and added the actual gear and cabanve later.

maybe different versions of -12 gear, beefups??

 

[Scooter7779h]

The only conflict potential I think is the upper gear leg where it goes into the fuselage gear bracket. I don't think the -18 gear cabanve tabs conflict with the PA-12 gear legs. But as you well know there is some crazy stuff out there on -12s, and YMMV......

Screwed up day out there flying today BTW. I am glad I have the dash that I do....... worth every ounce of weight.

Also, MTA turned on the 2G on the tower by the cabin.... Android rocks, full internet, speed not bad. Iphones sit dead with no service. Android rocking with four windows open. I used the Android also as a router, and ran the PC off of it with a wireless broadcast in the cabin. Totally rocking.

 

[mike mcs repair]

The only conflict potential I think is the upper gear leg where it goes into the fuselage gear bracket. I don't think the -18 gear cabanve tabs conflict with the PA-12 gear legs. But as you well know there is some crazy stuff out there on -12s, and YMMV......

Screwed up day out there flying today BTW. I am glad I have the dash that I do....... worth every ounce of weight.

Also, MTA turned on the 2G on the tower by the cabin.... Android rocks, full internet, speed not bad. Iphones sit dead with no service. Android rocking with four windows open. I used the Android also as a router, and ran the PC off of it with a wireless broadcast in the cabin. Totally rocking.

its probably time to call charlie at crosswinds on the gear tabs thing...

you can then use that nice router to serve wifi to your iphones and such...

how did we get along before all these gadgets & being connected....