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Pa-18 Project. It has begun!

M

Msbm4220

SPONSOR
I've made a few posts previously gathering opinions and such on this project. I have finally had an opportunity to transport all the pieces and such to my shop and have begun the inventory process. It appears I will definitely have more questions than answers.

It looks like the project started life as a 1951 L-21A with an O-290D. Records indicate that the engine was converted to an o-320 in '79. The engine log also indicates that the engine has undergone transformation up to a -C2B. The O-320 parts manual I have doesn't even mention C2B anywhere. So question 1..... Where can I find updated info on O-320 models and their specifics.

The wings appear to be 13 rib wings with fuel tanks in both wings. The left was wing was damaged hence why I believe this project even exists. The most recent project owner began to rebuild the left wing but time and interests changed. I have seen 13 rib wings mentioned in various posts and will research shortly. Question 2...All of the drawings in the Northland files show 15 rib wings...... Thoughts/concerns..???


The fuse has all the indications of a fairly decent 70 year old tube and fabric fuselage. No major corrosion and one section of lower left longeron has been replaced. Just forward of the instrument panel appears to be the plate where the data plate WOULD be attached. Either A it was painted over a couple times or B it doesn't exist, but I haven't seen an actual serial number for the fuse. I don't have an Airframe log but the engine log does have references to the N number it was installed in. It is highly possible when the aircraft was damaged it damaged the fuselage and the fuse I have is a donor from???? The fuse I have is a D window fuse whereas I believe an L-21A fuse should have the square "military" windows. Feel free to jump in here.

Looking forward to all the input I receive. Project should be fun.
-MB
 
The O-320-C2B is a certified engine per TCDS E-274

You would need the current parts book etc to find out what the difference between it and the A2B are.
An engine shop like Certified Engines Unlimited has all that data. Just getting it might be a hassle.
 
From the notes section of the TCDS


[TD="width: 171"]O-320-C2A, -C2B, -C3A, -C3B [/TD]
[TD="width: 598"]Same as O-320-B2A, -B2B, -B3A and B3B respectively, except have O-320-A series, low compression pistons, reduced ratings and lower grade fuel requirements. [/TD]

[TD="width: 171"]O-320-C1A, -C1B, -C2C, -C3C [/TD]
[TD="width: 598"]Same as O-320-B1A, -B1B, -B2C, -B3C respectively, except have been converted to low compression pistons.[/TD]
 
Best and most balanced Supercub I have ever been privileged to fly was a converted -95 with flaps and 160 engine. Two wing tanks, 13 rib wings, and Clevelands - otherwise stock. Very light.

It has since been modified - still a nice Cub, but somehow the balance is gone and it lost about 10 mph cruise.
 
Great info…. Thank you!!!

I’ve got an email into Clyde Smith with my fuse number to see where it’s from.

I intend to keep it certified. That being said, are all of the popular mods available through STC…brakes, wheels, dog leg, wip2000 of course (although I’m sure 1750 is plenty), can the -c2b change to higher compression pistons??, headerless fuel, …others..

Again, thanks for all the tips!!!!!
-MB
 
Don't know all parts changed but if the crank is still the O-290-D crank I would be reluctant to stress it more than it is already.
 
In 1994 this engine underwent what appears to be an overhaul/rebuild. Logbook entry is quite extensive and referenced work orders which I do not have. Lots of part numbers.

Crank case #L-772-39
Acc. Case. #69166
Crank shaft. #68606, Ser# 71500

Logbook states piston numbers
1. SL15357
2. Al75413p010
3. 75413
4. 75413

These don’t mean a lot to me yet, Log states no’s 1 & 2 are oversized. Is it strange to not have all 4 pistons sized equally??

I don’t really have an understanding yet of this info. Im just looking to figure out exactly what I have and determine my expectations and limitations going forward.

As always, thanks for info, tips, recommendations, and education!!!!

-MB
 
Heard back from Clyde with fuse info. It is a 1976 -150.

Appears to be in mostly stock form. There is an x-brace over the cabin. The rear seat cross bar is removable.

Where I want to go from here with help from Bill Rusks list is….
-reverse dog leg
-rear baggage door
-reinforced tail wheel attach to support baby bushwheel or similar
-dual tail lift handles
-firewall x-brace
-floor seatbelt attach points
-long step
-tail x-brace
-headerless fuel

Tires and wheels are a given. Extended gear up for debate. 2000lb gross also debatable. Thinking of using Stewart’s. This is mostly driven by the “green” products they use. My wife will definitely be on board with allowing the kids to be all hands on. (Ironically we then go and breath 100ll, go figure)

I think this list is mostly safety and functionality driven.
I printed the extensive STC list that Attlee Dodge has. I emailed them but have yet to hear anything.

as always, input is sought and appreciated. Trying to land on some STCs to get some fuse work started.

many thanks,
-MB
 
When it comes to the rear baggage door size does matter!! The bigger the better. Are you doing extended baggage or bellypod? Are you routing brake lines above the floor and out the sides for ease of matinance/inspection? Upper baggage door? Antenna mount for ELT and battery relocation? Now is the time to consider if you need extra tabs for any of the above. I would recommend the 2,000 lb weight update while wings are uncovered. Good to have from a legal/resale point, the plane will fly at 2,000 lbs just fine without it but 1750 really does not leave a lot of legal useful load. I am always willing to help increase the price of a simple rebuild by recommending mods so take my advice with a grain or full shaker of salt as needed.
DENNY
 
Msbm4220 said:
Tires and wheels are a given. Extended gear up for debate.
Click to expand...
Every time I see both the big tires and the extended gear mentioned together, I always wonder why both? The big tires do the same thing as the extended gear as far as providing a greater angle of attack when on the ground. Granted extended gear has uses if on skis.
 
Anything worth doing, is worth over-doing?

When going from 8.50s (22" generally) to 31 or 35" bushwheels you gain 6.5". 3" extended gear gets you to 9.5" more prop (and wing) clearance and more AOA on the ground roll, and as you say 3" more on skis, too. There is another benefit, which is giving you more rear cg when on the ground in full stall - more weight on the tail lets you brake a little more before raising the tail and/or nosing over. Increases castor angle for the tailwheel, as well.

More gooder.

skywagon8a said:
Every time I see both the big tires and the extended gear mentioned together, I always wonder why both? The big tires do the same thing as the extended gear as far as providing a greater angle of attack when on the ground. Granted extended gear has uses if on skis.
Click to expand...
 
Understood all that. I have seen when a plane is heavily loaded, the increased drag from that high angle of attack retards acceleration. In a tight situation it is possible not to be able to accelerate to a safe flying speed.
 
The first quest we have to ask is what are you planing on doing with the plane. I can run up a 30 grand list of "Simple must have Alaska mods" that is useless if this is going to be a weekend flyer to smooth grass/tar runways with hangers, and places to stay. So what type of flying do you plan on doing with the plane?
DENNY
 
DENNY said:
The first quest we have to ask is what are you planing on doing with the plane. I can run up a 30 grand list of "Simple must have Alaska mods" that is useless if this is going to be a weekend flyer to smooth grass/tar runways with hangers, and places to stay. So what type of flying do you plan on doing with the plane?
DENNY
Click to expand...

Very valid question. This was addressed in a different thread during the initial thought of this project.

I live in the southeast. Keep the Maule I currently fly at my home farm strip. The same will be true with the Supercub. Most flying is local to various grass strips and pastures I know are moderately improved. In the not to distant future I see camping/fishing trips with any one of my three boys all over the country. And Alaska is definitely a will-do!! People have been flying cubs to/from/in Alaska since dirt was invented. Now it's just a matter of what can make it easier, safer, more accommodating, and more pleasurable.

I guess the common approach is build to accomplish 90 percent of your missions.

Thankful for the input and suggestions.
-MB
 
If you are going to do major distance/time time trips with two people in a cub then by all means get the highest gross weight, max baggage area possible and have it pod friendly. 25 gal or bigger tanks on each side is also great to have. It is really not hard to properly adjust CG of a large load if you have a pod. 3 inch gear works great with most any tire and skis. A properly built travel cub will tend to weight a bit more but it will be a joy to fly because you can carry everything you need safely and in comfort with enough fuel (big tanks) to get to your destination.
DENNY
 
Progress report.

Since this is my first project I’m trying very hard not to lose control on mods and things but build a useful certified cub. After a significant amount of time looking at what I have, disassembling the partially assembled left wing, repairing some ribs, locating a few odds and ends, cleaning and priming both steel and aluminum parts, here is where I am.

The left wing was originally a 16 rib wing. Or at least the donated LE skins were from a 16 rib wing. The right wing is complete. It looks aged. Has the hat stiffener under the leading edge skin and a couple ribs which need replacing.

where I think I’m going is to complete the left wing as a 16 rib wing. Then rebuild the right wing as a 16 rib wing. Which require a few ribs and new skins. I can’t find the reference as of yet but I believe the LE stiffener can go away if you use .020 2024 skin. Any input on this?

I could be mistaken but this 16 rib transformation might accomplish one of the steps necessary to achieve the 1750 gross. I’ve read a few past threads about this but there are still a few lingering debates. The engine I have is an O-320 so this will definitely be 150-160 hp. Direction on STCs needed to legalize this plan??

Thank you for all the suggestions and input. This community is a blessing.

-MB
 
Msbm4220 said:
Progress report.

Since this is my first project I’m trying very hard not to lose control on mods and things but build a useful certified cub. After a significant amount of time looking at what I have, disassembling the partially assembled left wing, repairing some ribs, locating a few odds and ends, cleaning and priming both steel and aluminum parts, here is where I am.

The left wing was originally a 16 rib wing. Or at least the donated LE skins were from a 16 rib wing. The right wing is complete. It looks aged. Has the hat stiffener under the leading edge skin and a couple ribs which need replacing.

where I think I’m going is to complete the left wing as a 16 rib wing. Then rebuild the right wing as a 16 rib wing. Which require a few ribs and new skins. I can’t find the reference as of yet but I believe the LE stiffener can go away if you use .020 2024 skin. Any input on this?

I could be mistaken but this 16 rib transformation might accomplish one of the steps necessary to achieve the 1750 gross. I’ve read a few past threads about this but there are still a few lingering debates. The engine I have is an O-320 so this will definitely be 150-160 hp. Direction on STCs needed to legalize this plan??

Thank you for all the suggestions and input. This community is a blessing.

-MB
Click to expand...


pictures please
 
I could be wrong but I think you can get the 1750 gross with with fuselage and engine changes only, 13 rib wing is ok. Depending on which post you read you can even get to 2,000.
DENNY
 
DENNY said:
I could be wrong but I think you can get the 1750 gross with with fuselage and engine changes only, 13 rib wing is ok. Depending on which post you read you can even get to 2,000.
DENNY
Click to expand...

You are indeed correct. I have a '54 A Model with original 13 rib wings that I installed Wip's 2K upgross. Talking with their engineering dept prior to purchasing, they confirmed the 13 rib wing was not a factor for the upgross.
 
More ribs only raised the Vne and does not effect the gross weight. 1750 lb GW is 5/16" cabane bolts and cabane, 3 tubes at the battery box and engine. All the STC's for the O-320 that I have seen require that the airplane be upgrades to the PA18-150 configuration in regards to flaps and balanced elevators.

The outboard leading edge skin requires the stiffener if the older 3003 aluminum skin is used and the stiffener is not called out when the later .020" 2024-T3 skin is used.
 
Steve,
with regards to the flaps and balanced elevators….
I could find 12263 easy enough for the elevators. But when I start looking at flaps I see my “pa-18-150” parts manual appears to indicate the “150” has metal flaps. Is this accurate?? Can you lead me in the direction of the STC regarding flaps in this scenario?

There are a lot of penguins jumping off the ice berg!!!!!!
-MB
 
Msbm4220 said:
Steve,
with regards to the flaps and balanced elevators….
I could find 12263 easy enough for the elevators. But when I start looking at flaps I see my “pa-18-150” parts manual appears to indicate the “150” has metal flaps. Is this accurate?? Can you lead me in the direction of the STC regarding flaps in this scenario?

There are a lot of penguins jumping off the ice berg!!!!!!
-MB
Click to expand...
TC 1A2. Item 601. It's a minor alteration listed on the type certificate. No STC required.
https://drs.faa.gov/browse/TCDSMODEL/doctypeDetails

Piper drawing #12544 or #13766.

Try this: https://drs.faa.gov/browse
left side: design and production approvals > type certificate data sheets (tcds)
 
Msbm4220 said:
Steve,
with regards to the flaps and balanced elevators….
I could find 12263 easy enough for the elevators. But when I start looking at flaps I see my “pa-18-150” parts manual appears to indicate the “150” has metal flaps. Is this accurate?? Can you lead me in the direction of the STC regarding flaps in this scenario?

There are a lot of penguins jumping off the ice berg!!!!!!
-MB
Click to expand...
Piper used metal ailerons and flaps starting in about 1979.
 
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