Vertical Stabilizer (Fin) Assembly

[Roger & Alice Hoffman]

I've riveted the Fin Stabilizer Attach Bracket (FIN-33) to the Fin Main Spar
(ST-27) with the RV-1613 rivets as called for in the manual (9.3; #3). The
mandrel head on all 9 rivets does not appear to have pulled very far at all
into the barrel of the rivet. In most cases the end of the rivet barrel does
not wrap past the point of the mandrel head's maximum diameter.

I measured the thickness of the assembled parts (attach brkt; spar; and
doubler) at .280 inch thick. The manual says the RV-1613's grip length is
1/4 inch. All three pieces appear to be mated firmly against each other (no
burr's, and chromated between the parts).

I did not like the looks of the RV-1613's. I drilled them out and replaced
them with RV-1619's which, according to the manual, have a grip length of
3/8ths inch.

I could not see any problem doing so. However, being new at this, I wanted
to ask for (anyone's) opinions.

I faxed this question to MAM Tech last week but have not had a response from
them. I'm assuming they are probably all at Arlington.

R. Hoffman #687R
Eugene, OR USA





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[klehman]

Roger
You did the right thing. There are several places where you will need to
substitute a slightly different length bolt (or rivet) for your particular
airframe. Consider the manual as only a guide as there will always be errors or
slight changes in parts and such.
Ken

Roger & Alice Hoffman wrote:

I measured the thickness of the assembled parts (attach brkt; spar; and
doubler) at .280 inch thick. The manual says the RV-1613's grip length is
1/4 inch. All three pieces appear to be mated firmly against each other (no
burr's, and chromated between the parts).

I did not like the looks of the RV-1613's. I drilled them out and replaced
them with RV-1619's which, according to the manual, have a grip length of
3/8ths inch.

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[Richard DeCiero]

Roger and Alice,
Your message prompted me to inspect my assembled parts. My Fin-33 attach bracket is
.125 thick. The spar and doubler have an assembled/combined thickness of .110" at the
flanges. Each piece appears to be .050" thick. The three piece assembly after riveted
with 1613's measured .230 with a micrometer. I wonder if the spar or the doubler was
thickened up? My Rebel is S/N 446. Any and all comments welcomed.
Thanks,
Rick D.
Rebel S/N 446


Roger & Alice Hoffman wrote:

I've riveted the Fin Stabilizer Attach Bracket (FIN-33) to the Fin Main Spar
(ST-27) with the RV-1613 rivets as called for in the manual (9.3; #3). The
mandrel head on all 9 rivets does not appear to have pulled very far at all
into the barrel of the rivet. In most cases the end of the rivet barrel does
not wrap past the point of the mandrel head's maximum diameter.

I measured the thickness of the assembled parts (attach brkt; spar; and
doubler) at .280 inch thick. The manual says the RV-1613's grip length is
1/4 inch. All three pieces appear to be mated firmly against each other (no
burr's, and chromated between the parts).

I did not like the looks of the RV-1613's. I drilled them out and replaced
them with RV-1619's which, according to the manual, have a grip length of
3/8ths inch.

I could not see any problem doing so. However, being new at this, I wanted
to ask for (anyone's) opinions.

I faxed this question to MAM Tech last week but have not had a response from
them. I'm assuming they are probably all at Arlington.

R. Hoffman #687R
Eugene, OR USA

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[Roger & Alice Hoffman]

Richard DeCiero,

I re-measured my assembled parts again. My attach bracket, measured at
several points is .130 thick. The spar, measured on the flange at the bottom
end is .048 thick. The spar and doubler together, measured on the flange
adjacent to the attach bracket, is .105 thick. That would be .235 total
thickness.

I think I erred in my original email to the builder's list, by incorrectly
adding .048 into the equation again.

In any case, when I inspected the RV-1613 rivets I just was not comfortable
with the way they pulled. The mandrel heads looked like they could fall out
with a little vibration, so I drilled them out and replaced with the 1619's.

Brian Godden at MAM Tech subsequently sent me the following: "total
thickness there according to my calcs. is .225". This is within the grip
range of the 1613, so they should be fine. Those 3/16" rivets very often
leave the ball showing when getting near the limit of their grip range."

Perhaps I was just over reacting, but as long as using the 1619 rivets is
not unsafe (no one yet has told me it is), I feel better having done so.

Roger Hoffman #687R
Eugene, OR USA


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[Roger & Alice Hoffman]

Richard DeCiero,

Just as a side note on the RV-1613/1619 rivet discussion, I riveted the
horizontal stabilizer main spar/doubler/attach bracket together last night.
I noted that my manual specifically calls for the 1619 rivet for this
assembly, yet the parts are the same thickness as the Fin assembly weve been
discussing.

Roger

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