Flap Skin Source

[bagarre]

I just drilled off the skins on the first flap, not a bad job.
But some of these rivets look near impossible to buck.

[c170b53]

Are we talking about those little wedges?

[bagarre]

There are 4 ribs that run to the trailing edge.
I'm not seeing how you get a bucking bar in there to get the last two rivets without deforming the skin in the process while keeping everything straight.
I guess you could put a few pulled rivets in there.

[jonesronc]

Here's a How-To:

http://www.tennesseeaircraft.net/flaps-are-easy/

HTH, Ron

[bagarre]

That article really doesnt detail how to get the rivets in the rib without bending the skin.

[DaveF]

It's really not that hard, I don't know why you're making such a big deal out of this. All it takes is skill, experience, and good tools. I'm still working on the first part.

[bagarre]

It's really not that hard, I don't know why you're making such a big deal out of this. All it takes is skill, experience, and good tools. I'm still working on the first part.

I can do most anything if there is a YouTube video showing how

[sfarringer]

Probably the certified mechanic who is supervising you, can show you how it's done!

[bagarre]

Probably the certified mechanic who is supervising you, can show you how it's done!

Pretty sure it was a certified mechanic that shot the crappy rivets that caused me to replace the skins in the first place.
Got a log book entry and everything.
Certified != Competent

[sfarringer]

Hopefully the one you've chosen to supervise your work is competent.
I certainly agree that not all mechanics are created equal.
Just a gentle reminder that working on control surfaces is not on the list of preventive maintenance tasks that an owner can perform un-supervised.

[bagarre]

Is the trailing edge of the flap supposed to have two or three rivets per 3" section (between the ridges)?
The set I'm dealing with have three on the trailing edge but the holes aren't lined up nice enough to convince me their original.
The leading edge of the flap skin mostly has two but some of them have three ¯\_(ツ)_/¯

[c170b53]

Two I believe is correct, either side of the diamond club stamp. I just noticed I have a 2" crack on the top L/E of a flap due to wear from the wing trailing edge on my XP. Err....flap buttons were missing.

[Metal Master]

Is the trailing edge of the flap supposed to have two or three rivets per 3" section (between the ridges)?
The set I'm dealing with have three on the trailing edge but the holes aren't lined up nice enough to convince me their original.
The leading edge of the flap skin mostly has two but some of them have three ¯\_(ツ)_/¯

The original flap trailing edges were not riveted at all they were Spot welded. A process that is not covered in the repair manuals. They generally had two spot welds per flat section between the raised corrugation sometimes three. They still cracked and often the trailing edges would be repaired by installing rivets. Sometimes the trailing edge where they were welded together would pop open due to corrosion and need to be reattached. The spot welds were never as well placed as rivets as in later model trailing edges. So that if they were drilled out in the center of the spot welds they would make the rivet pattern look strange. I have always wondered how one would set up a spot welding machine to do those spot welds. Something I have thought about trying to do. It is just easier to rivet them in the field. Two or three rivets would be appropriate depending on what you are trying to accomplish. If installing a bulb strip which will make keeping the trailing edge straight easier as it simplifies the issue, rivets are the only way not that spot welding would necessarily be possible. I have rebuilt 170A flaps before and have new parts I have manufactured to replace / repair the flap drive bracket. I have a pair to repair now however it is just not a front burner project or I would take pictures to show the process. The flap skins are rolled up in a box with the new parts awaiting my attention. I could take pictures to show the bucking bars I use but that is not a front burner project either. I have several thin bars welded to re-bar and long one inch by one inch bars to do the job. (Skill, experience and 47 years of doing sheet metal repair work is the trick for me)
It is strange to see an elevator spot welded on one side of the airplane and riveted on the other. Most people would never notice. For your viewing pleasure a picture my Son the just graduated A&P school 3.9 grade point average assistant helping. He's the one with the shaved head?

Lower Aileron skin peeled back during riveting RS.jpg

[bagarre]

Thanks for the info.
I need to pay closer attention when looking at 170's for now on. I've never noticed one with spot welds.

[bagarre]

Next question:
While masking off the rudder, I noticed the ribbed diamonds were cut back on the skin leading edge by bout 45 degrees.
That one is an original skin - best I can tell.

Did the flaps have the same taper originally or were they just straight cut? Odd that the rudder would be that way but the others dont but I dont have any originals to compare to.
tks