Rivet advise please

I have to replace the trailing edge end of a stamped aluminum rib from
a '47 Tcraft. I've cut away the corroded portion, bent metal to
replace that part and would like to use Cherry "N" rivets to hold it
in place.

I have some questions regarding what spec to look for when ordering.
A. Rivet Material: 5052 Aluminum or 5056 - does it make any
difference for this old a rib?
B. Mandrel Material: Aluminum or steel - am I correct that
dissimilar metals could cause a problem and I should stick with
aluminum? In that case why make a steel mandrel?

Thanks in Advance - Mike

On Aug 21, 8:32*am, mhorowit wrote:
I have to replace the trailing edge end of a stamped aluminum rib from
a '47 Tcraft. I've cut away the corroded portion, bent metal to
replace that part and would like to use Cherry "N" rivets to hold it
in place.

I have some questions regarding what spec to look for when ordering.
*A. *Rivet Material: 5052 Aluminum or 5056 - does it make any
difference for this old a rib?
*B. *Mandrel Material: Aluminum or steel - am I correct that
dissimilar metals could cause a problem and I should stick with
aluminum? In that case why make a steel mandrel?

Thanks in Advance - Mike

Is there some reason you can't use driven rivets?

On Aug 21, 10:16*am, 150flivver wrote:
On Aug 21, 8:32*am, mhorowit wrote:

I have to replace the trailing edge end of a stamped aluminum rib from
a '47 Tcraft. I've cut away the corroded portion, bent metal to
replace that part and would like to use Cherry "N" rivets to hold it
in place.

I have some questions regarding what spec to look for when ordering.
*A. *Rivet Material: 5052 Aluminum or 5056 - does it make any
difference for this old a rib?
*B. *Mandrel Material: Aluminum or steel - am I correct that
dissimilar metals could cause a problem and I should stick with
aluminum? In that case why make a steel mandrel?

Thanks in Advance - Mike

Is there some reason you can't use driven rivets?

Not really (please correct me if I'm wrong, I'm stumbling around here)
except
A. "pop" rivets seem easier to apply
B. I don't have access to the "official" tools for setting either
standard or flat head rivets.
C. I could /might be able to set a flathead rivet but insuring the
shaft is perfectly in line with the driving pin could be a problem.
Open to suggestions - Mike

On Aug 21, 6:32*am, mhorowit wrote:
I have to replace the trailing edge end of a stamped aluminum rib from
a '47 Tcraft. I've cut away the corroded portion, bent metal to
replace that part and would like to use Cherry "N" rivets to hold it
in place.

Well, I think you can get the strength you need from a reasonable
pattern of Cherry commercial rivets as you propose, but I also think
that A&Ps and IAs are going to look askance at it, and you run the
risk of having them make you redo it. That's one good reason to follow
the guidelines of AC43.13, it gives folks that warm fuzzy feeling they
need in order to sign stuff off as being something like airworthy.

I have some questions regarding what spec to look for when ordering.
*A. *Rivet Material: 5052 Aluminum or 5056 - does it make any
difference for this old a rib?

If you're set on using the Cherry commercial rivets, I'd suggest
either MSP monel rivets or the BSPQ high-shear aluminum rivets. The
MSPs have about the same shear strength as MS20470ADs of equivalent
size, and the monel is galvanically about as neutral as you can get
outside of aluminum. The Cherry aluminum BSPQs have similar shear
properties and a nice stem retension feature, and look enough like
CherryMax to the casual eye that they might pass for such under a coat
of primer, and you can honestly say "Yup, I used Cherry rivets here."

B. Mandrel Material: Aluminum or steel - am I correct that
dissimilar metals could cause a problem and I should stick with
aluminum? In that case why make a steel mandrel?

One reason to avoid aluminum stems is that they are so much weaker
than the steel stems that they have to make the rivet itself out of
very soft material in order to be so malleable that it can be pulled
into shape by the weaker stem. So aluminum stem rivets are generally
much weaker than steel stem rivets. I never use aluminum stem pops on
aircraft parts.

All told, if you're so set against hard rivets I'd suggest that you
just bite the bullet and use CherryMax or whatever at a dollar a pop
or so. They'll look AC43.13 official and that will make signoff more
likely painless.

However, if you're going to make a habit of doing riveted repairs, it
really pays to get a few simple tools to drive solid rivets. I've done
plenty of MS20470AD and MS20426AD rivets with a hammer and a drift,
and maybe a set clamped in the jaws of a vise.

Thanks, Bob K.
www.hpaircraft.com/hp-24

On Thu, 21 Aug 2008 11:26:54 -0700 (PDT), Bob Kuykendall
wrote:



However, if you're going to make a habit of doing riveted repairs, it
really pays to get a few simple tools to drive solid rivets. I've done
plenty of MS20470AD and MS20426AD rivets with a hammer and a drift,
and maybe a set clamped in the jaws of a vise.

Thanks, Bob K.
www.hpaircraft.com/hp-24


Bob - thanks for your reasoned response. I'd like to hear more about
how you lined the drift along the rivet axis so that you got a
symetrical mushroom head - Mike

On Aug 21, 2:00*pm, Michael Horowitz wrote:

Bob - thanks for your reasoned response. I'd like to hear more about
how you lined the drift along the rivet axis so that you got a
symetrical mushroom head - Mike

Just like anything, it takes a bit of practice. If your rivet is
something like the right length (I will often cut rivets so they're on
the short end of the range suggested in AC43.13) and you hit it
something like straight on you'll get a reasonably good shop tail
after a couple of strikes. If the shank tends to bend over the rivet
is too long. If it bends just a little bit you may still be able to
skoosh it into an acceptable shop tail with a little drift correction.

One of the main points of riveting is that the range of acceptable
variation is actually pretty wide. AC43.13 shows several minor defects
that are acceptable. On the Vans Air Force forums I've seen tests
cited that showed that MS20470AD rivets develop full strength even
with some pretty heinous-looking defects.

Thanks, Bob K.

On Thu, 21 Aug 2008 14:25:38 -0700 (PDT), Bob Kuykendall
wrote:

On Aug 21, 2:00Â*pm, Michael Horowitz wrote:

Bob - thanks for your reasoned response. I'd like to hear more about
how you lined the drift along the rivet axis so that you got a
symetrical mushroom head - Mike

Just like anything, it takes a bit of practice. If your rivet is
something like the right length (I will often cut rivets so they're on
the short end of the range suggested in AC43.13) and you hit it
something like straight on you'll get a reasonably good shop tail
after a couple of strikes. If the shank tends to bend over the rivet
is too long. If it bends just a little bit you may still be able to
skoosh it into an acceptable shop tail with a little drift correction.

One of the main points of riveting is that the range of acceptable
variation is actually pretty wide. AC43.13 shows several minor defects
that are acceptable. On the Vans Air Force forums I've seen tests
cited that showed that MS20470AD rivets develop full strength even
with some pretty heinous-looking defects.

Thanks, Bob K.

I better check my measurements again; could be I'm leaving too long a
shank. After you cut the rivet, you do file the cut end flat, right? -
Mike

On Aug 21, 3:21*pm, Michael Horowitz wrote:
After you cut the rivet, you do file the cut end flat, right? -
Mike-

When I cut a rivet with wire cutters or such I'll generally touch it
to the disk sander to clean it up. But a real rivet cutter will
generally leave an adequate surface finish. Unless there's a crack or
a nasty barb I generally just smash the end flat.

Most A&P's would think very poorly of any Cherry rivet used where a solid
rivet is just as easily installed. My experience has been that solid rivets
perform far better than any blind rivet if installed correctly. Consider
buying the tools, practicing, and using solid rivets.
Where I work, much of the sheetmetal jobs are replkacing working Cherry Max
or Cherry rivets that have started to work loose. They should only be used
where the back side is not accessible.
"mhorowit" wrote in message
...
I have to replace the trailing edge end of a stamped aluminum rib from
a '47 Tcraft. I've cut away the corroded portion, bent metal to
replace that part and would like to use Cherry "N" rivets to hold it
in place.

I have some questions regarding what spec to look for when ordering.
A. Rivet Material: 5052 Aluminum or 5056 - does it make any
difference for this old a rib?
B. Mandrel Material: Aluminum or steel - am I correct that
dissimilar metals could cause a problem and I should stick with
aluminum? In that case why make a steel mandrel?

Thanks in Advance - Mike

Charles wrote:
Most A&P's would think very poorly of any Cherry rivet used where a solid
rivet is just as easily installed. My experience has been that solid rivets
perform far better than any blind rivet if installed correctly. Consider
buying the tools, practicing, and using solid rivets.
Where I work, much of the sheetmetal jobs are replkacing working Cherry Max
or Cherry rivets that have started to work loose. They should only be used
where the back side is not accessible.

They can be used for nonstructural applications also. I'd go with
what the designer called for or with what was there in the first place,
but that's just me. I'm sufficiently old fashioned about things like
this I wouldn't use fiberfill nuts on flight controls either.

Dan, U.S. Air Force, retired