Truss rib repair tool

Scott 2020 · Dec 21, 2020

Hi all
Got tired of waiting for a rib repair kit which is back ordered so decided to try and fabricate the parts myself. Turns out it's not that difficult so thought I'd share.

Note that this is not mass production, but works for typical repairs. Make and swage any length of truss reinforcement.

I also made a relatively simple tool that swages the truss splices nice and snug.

First the splice:
I'm using 3003H14 .020" tried 2024T3 but the truss material is not strong enough to support the bend in place.

Anyway start with a strip 1.660" wide and the length of the desired splice.

Mark .350" and 1.310" on one side and .580 and 1.080 on the other. Brake these latter two marks to form a U channel.

I use a piece of 1/2" bar stock to mount the U channel in the vice and manually brake the .350 and 1.310 marks to form the hat section.

The "swaging" tool is three pieces of 3/8" angle iron welded to a vicegrip welding clamp as shown. The center piece needs to float laterally but resist compressive loads so it's held in place by .032" chromoly. I added 1/8" aluminum spacers to improve the way it functions. see pics

Scott 2020 · Dec 21, 2020

Now for the brace section:

2024T3 .020" is used for this.

Cut a strip about 1.375" by a little more than the length of the brace you're replacing.

Brake it along the ceterline to 90degrees.

Flip it over on the brake and use your fingers or a piece of wood to hold it in position as you clamp the brake down.

Turn it end for end and brake the other side

Then brake the two side flanges and trim off the excess along the length.

There may be a need to form by hand a little to get the rivet surfaces to lay flat, but that's it.

I don't have dimensions cuz I just eyeball it but easy enough to measure the originals if you need it.

Steve Pierce · Dec 22, 2020

Very nice, thanks for sharing this. I have boxes of Piper ribs I need to start repairing in my spare time.

mike mcs repair · Dec 22, 2020

if rib is bent and not broken, form back to shape and slide a 1/2" piece of .016" or .020" aluminum into "T" section and succure with 3 spar screws. much better than the piper wrap around patch for broken sections. leaves no lumps in fabric.

cubdriver2 · Dec 22, 2020

Paul Babcock uses unrepairable damaged rib sections to repair rebuildable ribs. Cut to size then open up the T with a half inch wide pointed wood stick and splice it over where the damage is and rivit back together, no bump.

Glenn

Scott 2020 · Dec 22, 2020

Oh there's lots of options, particularly for non-certified applications, but although the piper repair is a "service memo" and therefor not nessarily mandatory, I need to be able to reference "acceptable data" which would include piper publications, AC43-13 etc.. I'm not aware of acceptable data that specifies self tapping screws for sheet metal repairs of any kind. A lot of the damage I'm repairing is actually previous attempts using pop rivets, or damage caused by Pk screws.

I do use the "web" method where the truss is not cracked and there is an exisiting web type element. For example the trailing edge area of the outboard ribs where the bow attaches.
I also put gussets where there is clearly weakness, like the ribs forward of the fuel tank area .

astjp2 · Dec 30, 2020

All of the material to build original ribs were roll formed, the new material winds up being bent in a brake. It works but not as light as a factory rib. I have a 1940 blueprint that says the rib should weigh 4.8 oz, that was a full length rib. Now I just need to figure out what 2S 1/2 hard material is and what would be a replacement modern material. I know the company who made the original T form but I am not about to spend $1500 to buy material that I am not sure if I could find a use for. Tim

Steve Pierce · Dec 30, 2020

Piper formed the T themselves. Bought the aluminum in huge rolls and ran it through a series of rollers to form it. Will post some pics tomorrow.

mike mcs repair · Dec 30, 2020

Steve Pierce said:
Piper formed the T themselves. Bought the aluminum in huge rolls and ran it through a series of rollers to form it. Will post some pics tomorrow.

PULL draw bench? like shown in the video? I thought....

interested in seeing your pictures...

mike mcs repair · Dec 30, 2020

astjp2 said:
.. Now I just need to figure out what 2S 1/2 hard material is and what would be a replacement modern material. ..

https://www.aircraftspruce.com/catalog/mepages/aluminfo.php

modern = 1100 series

astjp2 · Dec 30, 2020

mike mcs repair said:
https://www.aircraftspruce.com/catalog/mepages/aluminfo.php

modern = 1100 series

I have seen that, but it does not act like 1100, more like a different alloy like 3003 or 5052? unless 75+ years of age have changed the hardness...

astjp2 · Dec 30, 2020

Steve Pierce said:
Piper formed the T themselves. Bought the aluminum in huge rolls and ran it through a series of rollers to form it. Will post some pics tomorrow.

I have seen the video too, this company claims to have been one of the war time suppliers, they have a lot of different forms that they did probably for many companies. Its not like we can contact Piper to make us new T sections so we can repair ribs ourselves. They sure were light weight though. Total material thickness was about .025...and about 1-3/4" wide by what 12'?

Scott 2020 · Dec 30, 2020

astjp2 said:
Now I just need to figure out what 2S 1/2 hard material is and what would be a replacement modern material. Tim

2S is 1100
1/2hard is H4

Scott 2020 · Dec 30, 2020

I should also mention de-riveting cuz the stock rivets can be a pain to remove.
The "secret" is don't be tempted to drill from the upset side. It seems inviting as there's a nice little crater to guide your drill bit, but the upset (or shop) head is rarely on center.

Use a good carbide bit. Support the work. If necessary, center punch the round head, then drill the head, angling your bit to "steer" it on center. If you're on center the body of the rivet will push through when the head separates, and the aluminum won't be touched.

I use a .094" bit. It has enough of a point that I can press it into the rivet (not rotating) to make enough of a mark that I can then back off the pressure and start the drill without it slipping off the head. Note that the bit rarely starts out on center, which is why you need to "steer" it as it cuts. Slow speed works best.

Even with this, many of the holes will have been enlarged by the rivet.

mike mcs repair · Dec 30, 2020

Scott 2020 said:
I should also mention de-riveting cuz the stock rivets can be a pain to remove.
The "secret" is don't be tempted to drill from the upset side. It seems inviting as there's a nice little crater to guide your drill bit, but the upset (or shop) head is rarely on center.

Use a good carbide bit. Support the work. If necessary, center punch the round head, then drill the head, angling your bit to "steer" it on center. If you're on center the body of the rivet will push through when the head separates, and the aluminum won't be touched.

I use a .094" bit. It has enough of a point that I can press it into the rivet (not rotating) to make enough of a mark that I can then back off the pressure and start the drill without it slipping off the head. Note that the bit rarely starts out on center, which is why you need to "steer" it as it cuts. Slow speed works best.

Even with this, many of the holes will have been enlarged by the rivet.

I just grind them off with a dremel and cutoff wheel.

Sent from my iPhone using SuperCub.Org mobile app

Scott 2020 · Dec 30, 2020

Tough not to touch the aluminum with the wheel.. for me anyway drilling is much faster and more precise.
S

skywagon8a · Dec 31, 2020

mike mcs repair said:
https://www.aircraftspruce.com/catalog/mepages/aluminfo.php

modern = 1100 series

1100H4 http://www.metalreference.com/INFO_Aluminum.html
H4 is half hard. Straight 1100 is soft.

Steve Pierce · Dec 31, 2020

Here is the machine that forms the T section. To the right you can see the giant spool of aluminum used to make the T.

Steve Pierce · Dec 31, 2020

The tool used to form the leading edge sections.

Steve Pierce · Dec 31, 2020

The rib parts used to assemble.

Rivet tool in the background.

Steve Pierce · Dec 31, 2020

Another picture of the rivet tool.

View attachment 53396

View attachment 53397

Steve Pierce · Dec 31, 2020

Another picture of the rivet tool and a pallet of aluminum for making the ribs to the right.

Steve Pierce · Dec 31, 2020

The preceding photos were taken inside the Piper plant at Lock Haven, PA sometime in 1977 by Clyde Smith Jr.

Steve Pierce · Dec 31, 2020

Along with these.

Steve Pierce · Dec 31, 2020

and these.

Truss rib repair tool

Registered User

Thunder Bay Ontario

Attachments

Registered User

Thunder Bay Ontario

Attachments

Graham, TX

Registered User

chugiak AK

Attachments

upstate NY

Registered User

Thunder Bay Ontario

Attachments

Registered User

Utah/Alaska

Graham, TX

Registered User

chugiak AK

Registered User

chugiak AK

Registered User

Utah/Alaska

Registered User

Utah/Alaska

Registered User

Thunder Bay Ontario

Registered User

Thunder Bay Ontario

Registered User

chugiak AK

Registered User

Thunder Bay Ontario

SE Mass MA6

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Graham, TX

Attachments

Similar threads