The Murphy Builders Site

Question: Should I use Avex rivets supplied by MAM or Cherrymax or
Cherry Q rivets? See below.

I'm getting ready to rivet new parts that MAM sent me to fix cracks
within my stinger attach bulkheads (previously posted on this list). I
got into a debate at the airport with several A&P's, including a United
mechanic, about using the MAM "standard" Avex rivet. One well respected
A&P said I absolutely had to use "Cherry Q" rivets; that he'd never use
an Avex rivet. Now, I know that the vast majority of pull rivets that
MAM uses on tons of planes that are reliabily operating are Avex rivets.
Nonetheless, I respect these folks opinions. I did a bit of research on
the web. Here's a couple of interesting comments about the Cherry brand
of rivets:

CHERRY Q-RIVET Cherry Q Rivet Diameter
<http://www.bonaero.com/images/CherryQrivet.GIF>
Cherry Q Rivet <http://www.bonaero.com/images/CQ42ASP.GIF> The poor
man's Cherrymax rivets. A commercial grade pop rivet that retains the
grip length of the stem within the rivet to augment shear strength.
Because of the mandrel, length selection must be accurate. Can be used
for structural applications (but not FAA approved).

...at http://www.bonaero.com/Rivets.htm

And here's what that same site says about Cherrymax rivets:

CHERRYMAX RIVETSThis rivet supercedes and improves upon all previous
Cherry blind rivet designs. By far the best stem retention system and
strength to weight ratio of all blind rivet systems. 3200 series are
aluminum rivet and steel stem, 3500 series are CRES.

--------------
I really, really want to always do things the best possible way that
makes sense. Seems to me that if I start popping rivets, breaking
rivets loose or such on these parts, e.g. FUS-358 where it rivets to the
fuselage, I have a major problem before the entire structure fails. I
would catch loose/problem rivets in a pre-flight (eventually), well
before the problem got critical.
-----------------------

Thoughts on rivet type?

Thank you,

Ted Waltman
Moose N142SR




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Hi Ted,
I am comfortable with Avex rivets because I think I understand their
properties. Avex rivets are just fine if the rivet spacing is designed for
that rivet. What I believe, your A&P is saying is that Avex rivets don't
have the shear strength of a same diameter Cherry. That's true but remember
the rivet count is the multiplier for total shear. The down side to Cherry's
is they are a pain to drill out. Some of the questions are, do you trust the
design, will you use fewer rivets, are the parts predrilled, were there
instructions for the install? The shear strength of an 1/8" Avex is about
165 lbs, remember the avex rivet is not a pop rivet.
Al
----- Original Message -----
From: "Ted Waltman" <tedwaltman@i1ci.com>
To: "'Murphy List'" <rebel-builders@dcsol.com>
Sent: Sunday, October 02, 2005 8:15 PM
Subject: Rivet types

Question: Should I use Avex rivets supplied by MAM or Cherrymax or
Cherry Q rivets? See below.

I'm getting ready to rivet new parts that MAM sent me to fix cracks
within my stinger attach bulkheads (previously posted on this list). I
got into a debate at the airport with several A&P's, including a United
mechanic, about using the MAM "standard" Avex rivet. One well respected
A&P said I absolutely had to use "Cherry Q" rivets; that he'd never use
an Avex rivet. Now, I know that the vast majority of pull rivets that
MAM uses on tons of planes that are reliabily operating are Avex rivets.
Nonetheless, I respect these folks opinions. I did a bit of research on
the web. Here's a couple of interesting comments about the Cherry brand
of rivets:

CHERRY Q-RIVET Cherry Q Rivet Diameter
<http://www.bonaero.com/images/CherryQrivet.GIF>
Cherry Q Rivet <http://www.bonaero.com/images/CQ42ASP.GIF> The poor
man's Cherrymax rivets. A commercial grade pop rivet that retains the
grip length of the stem within the rivet to augment shear strength.
Because of the mandrel, length selection must be accurate. Can be used
for structural applications (but not FAA approved).

...at http://www.bonaero.com/Rivets.htm

And here's what that same site says about Cherrymax rivets:

CHERRYMAX RIVETSThis rivet supercedes and improves upon all previous
Cherry blind rivet designs. By far the best stem retention system and
strength to weight ratio of all blind rivet systems. 3200 series are
aluminum rivet and steel stem, 3500 series are CRES.

--------------
I really, really want to always do things the best possible way that
makes sense. Seems to me that if I start popping rivets, breaking
rivets loose or such on these parts, e.g. FUS-358 where it rivets to the
fuselage, I have a major problem before the entire structure fails. I
would catch loose/problem rivets in a pre-flight (eventually), well
before the problem got critical.
-----------------------

Thoughts on rivet type?

Thank you,

Ted Waltman
Moose N142SR