Today's Message Index:
----------------------
1. 04:41 AM - Re: Re: rivets working (Charles Kuss)
2. 05:09 AM - Re: Re: rivets working (Hedrick)
3. 06:39 AM - Re: Re: rivets working (Jack Hilditch)
4. 07:36 AM - Re: IMC - What If??? (J Riffel)
5. 08:07 PM - Re: Re: rivets working (Hedrick)
Message 1
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| Subject: | RE: rivets working |
Keith,
When & if you drill out one or more of these smoking rivets, inspect the countersink
that the rivet nestles into. Local RV owners report that rivets installed
into countersunk rather than dimpled holes have a much greater tendency to
"smoke". Considering the thin (.016") material of the empennage skins, all holes
should be dimpled.
Charlie Kuss
--- On Mon, 9/29/08, Hedrick <khedrick@frontiernet.net> wrote:
> From: Hedrick <khedrick@frontiernet.net>
> Subject: RE: RV-List: RE: rivets working
> To: rv-list@matronics.com
> Date: Monday, September 29, 2008, 11:04 PM
> Hi John,
>
>
>
>
>
> I suspect that to really stop the smoking rivets I need to
> find the cause of
> the flight strain and stop it first. I am not sure where
> to start. i cant
> tell if I have corrosion in the rivets, I don't see any
> from the top.
>
>
>
> I am still wondering if this is a common or rare occurrence
> in the 6.
>
>
>
> Thanks for your help,
>
>
>
> Keith
>
> 64DK
>
>
>
> Do not archive
>
>
>
> _____
>
> From: owner-rv-list-server@matronics.com
> [mailto:owner-rv-list-server@matronics.com] On Behalf Of
> John Cox
> Sent: Sunday, September 28, 2008 10:31 PM
> To: rv-list@matronics.com
> Subject: RE: RV-List: RE: rivets working
>
>
>
> Working rivets, sometimes called "Smokin Rivets"
> can be the result of flight
> induced stress and strain from flight forces, airframe
> design technique and
> riveting technique. Often, the removed rivets have
> "Fretted" in their
> respective holes. Fretting is a form of corrosion.
>
>
>
> The removal and re-riveting is one method of remediation.
> Installing the
> replaced rivets "Wet" is another. There are lots
> of RV6 guys who should
> pipe in as to whether this is a reasonably common incident.
>
>
>
> I have completed a Pre-purchase Inspection and then
> subsequent Conditional
> Inspection on a 9 year old, 900 hour 6A without such a
> finding on a base
> white topcoat. Cracks which developed early in the flight
> life have been
> followed without apparent growth. We measured each and
> documented them for
> quantitative comparison next January. These are valued
> issues to discuss.
> The original owner moved onto an RV-10 and is now tackling
> an RV-3 project.
>
>
>
> John Cox
>
>
>
> From: owner-rv-list-server@matronics.com
> [mailto:owner-rv-list-server@matronics.com] On Behalf Of
> Hedrick
> Sent: Sunday, September 28, 2008 7:33 PM
> To: 'Hedrick'; rv-list@matronics.com
> Subject: RV-List: RE: rivets working
>
>
>
>
>
> Any thoughts on some rivets that are working in the
> horizontal stabilizer in
> my RV 6. it is the inboard rivets and it is on both
> sides. I have
> noticed this over a 3 or 4 yr period and it continues to
> involve more
> rivets.
>
>
>
> Is this a common thing in older rv's, mine is a vintage
> 1991. in fact it
> was # 9 rv 6 kit sold. The air frame has almost 1000 hrs
> on it. how do I
> stop it and how do I fix the damage ?
>
>
>
> Thanks
>
>
>
> Keith Hedrick
>
> 64DK
>
> @ 3LF
>
>
> Checked by AVG.
> 9/27/2008 1:11 PM
>
>
> Checked by AVG.
> 9/27/2008 1:11 PM
>
>
> Checked by AVG.
> 9/27/2008 1:11 PM
>
>
>
>
> http://www.matronics.com/Navigator?RV-List
>
> http://forums.matronics.com
>
> http://www.matronics.com/contribution
>
>
>
>
>
>
>
> Checked by AVG.
> 1:30 PM
Message 2
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| Subject: | RE: rivets working |
Hello Jack,
After more reading on that list, I am thinking that maybe I should not
use a
stainless cherry blind rivet because of the dissimiliar metals corrosion
problem that I could cause. My first thought was to drill them out and
use
the stainless. But even if I do that I still have a rivet that will
=91smoke=92 because I don=92t think that the cherry blind will be as
strong as the
driven rivet and prob I still have the problem that caused the rivets to
=91smoke=92. ???
any thoughts ?
Keith Hedrick
1991 Rv 6
_____
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Jack Hilditch
Sent: Monday, September 29, 2008 9:04 AM
Subject: RE: RV-List: RE: rivets working
Good morning,
There=92s an excellent discussion on the engineering tips forum on
rivets and
replacement (albeit on much heavier airframes) but it is certainly worth
a
read.
HYPERLINK
"http://www.eng-tips.com/viewthread.cfm?qid=15349&page=6"http://www.e
ng-tips
.com/viewthread.cfm?qid=15349&page=6 I would also guess that you
could get
a specific answer there as well.
Regards,
Jack
Riviting my RV-9A Fuselage at the moment.
_____
Checked by AVG.
9/29/2008
7:25 PM
Message 3
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| Subject: | RE: rivets working |
Hi Keith,
I don't really have a specific suggestion on replacement strategy which is what
led me to the engineering tips list in the first place. I was looking for
references on 'wet' rivet replacement. I would suggest posting your question to
that list so we can all benefit from what that wealth of knowledge might be able
to give us. I do, however, have a story on why I think this is such an important
topic, particularly to those of us who build and fly our own creations.
I spent quite a few years racing sailboats, primarily in salt water
environments. Most masts and more than a few hulls at the time were aluminum
while hardware (fairleads, turning buckles, screws, etc.) were either stainless
or bronze. Mechanically fastening dissimilar metals in a saline environment is,
in essence, creating a battery. What happens then is the least noble metal
becomes sacrificial and aluminum was almost always the 'sacrificial lamb.' In
other words, aluminum surrendered its structural properties and turned to
aluminum oxide. Periodically (at least once every year in those days) we would
pull masts out of the boats to remove all rigging and fasteners. Aluminum oxide,
a white powder, would be present everywhere dissimilar metals came into contact.
We tried many and varied electrostatic barrier coatings to minimize the
electrolysis but none of them provided a 100% solution. We knew we had a problem
but those old 'gotchas' of time, technology, costs and schedules demanded we
stick with a solution we knew would allow us to at least stay within a
predictable serviceability matrix through constant maintenance. Was it ideal?
Absolutely not, but it was what we had to work with at the time.
It really got our attention, at one point in the late 1970's, when a
mast-mounted halyard reel winch on a sixty-foot sailboat, under shear load in
the vicinity of 6000+ lbs, was incorrectly fed its 3/8" 7x19 galvanized halyard
cable. The cable imparted a 'racking' or fulcrum force to the winch thereby
putting its upper SS fasteners into compression and its lower SS fasteners into
tension. These fasteners had quietly built up a significant barrier coat of
aluminum oxide between them and the aluminum mast due to an errant electrical
current being introduced elsewhere in the (also) aluminum hull, nowhere near the
mast-mounted winch. The result was the lower SS winch fasteners pulled out of
the mast under load and the winch tore off the mast with great force. The
modulus of elasticity in the galvanized halyard cable allowed it to store
significant energy which it then used to propel a 50+ lb winch upward into the
face of the deckhand operating it. The result was a broken jaw, several lost
teeth, several other facial bones broken, a concussion and a (this is not a
drill) man overboard exercise at sea. It caught our attention without any doubt.
It also pointed out to us that even when you run regular, scheduled and thorough
maintenance schedules, unexpected elements creep in.
We eventually traced the errant electrical current to a corroded bonding strap
on a sacrificial anode attached to a through-hull fitting. That missing anode
allowed current from another boat in the marina to enter our hull through an
unprotected conduit making the entire boat and rig into an active battery. We
found considerably more electrolysis than normal during the immediately
scheduled haul out. It was everywhere and had weakened a number of fastening
points where stainless met aluminum.
This is a long-winded way to say I'm a true believer and have great respect for
making sure mechanical fastenings in an aluminum structure are properly done,
regularly maintained and constantly inspected, particularly when it is my butt
sitting in the aircraft at altitude.
Regards,
Jack
_____
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Hedrick
Sent: Tuesday, September 30, 2008 8:09 AM
Subject: RE: RV-List: RE: rivets working
Hello Jack,
After more reading on that list, I am thinking that maybe I should not use a
stainless cherry blind rivet because of the dissimiliar metals corrosion problem
that I could cause. My first thought was to drill them out and use the
stainless. But even if I do that I still have a rivet that will 'smoke'
because I don't think that the cherry blind will be as strong as the driven
rivet and prob I still have the problem that caused the rivets to 'smoke'.
???
any thoughts ?
Keith Hedrick
1991 Rv 6
_____
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Jack Hilditch
Sent: Monday, September 29, 2008 9:04 AM
Subject: RE: RV-List: RE: rivets working
Good morning,
There's an excellent discussion on the engineering tips forum on rivets and
replacement (albeit on much heavier airframes) but it is certainly worth a read.
http://www.eng-tips.com/viewthread.cfm?qid=15349
<http://www.eng-tips.com/viewthread.cfm?qid=15349&page=6> &page=6 I would also
guess that you could get a specific answer there as well.
Regards,
Jack
Riviting my RV-9A Fuselage at the moment.
_____
Checked by AVG.
9/29/2008 7:25 PM
Message 4
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| Subject: | Re: IMC - What If??? |
Just another 2 cents.
My objectives were IFR, simple and reliable. Because I've gone thru a vacuum
pump failure just as I was about to enter IMC, I wanted to avoid that again.
So *NO VACUUM*!
So here's what I chose for my RV7A:
Com: GNS430, Icom A200;
Backup: Icom handheld (w/ jack to external antenna)
Nav: GNS430 (GPS, Nav);
Backup: 396 (GPS), Icom handheld (nav)
AI: Trutrack ADI Pilot II (battery backup if power fails)
Backup: 396 (it's a little slow to respond - but it's quick
enough for an emergency)
Compass: ADI Pilot II
Backup: Vert. Card compass, 396
Weather: 396 XM Weather
Backup: none
Heated Pitot
Backup: none
Engine monitor: GR Engine Analyzer
Backup: Steam gauges for: Tach, Manifold Pressure & Left/Right
Fuel
Altimeter
Backup: 396 (a little off - but insignificant in an emergency)
Airspeed
Backup: my butt
Transponder
Backup: none
ELT
Backup: both handheld and cell phone to call for help
Cockpit lighting
Backup: flashlights
Nav/Strobe lights
Backup: none
AudioPanel (w/ intercom)
Backup: none
TOTAL Electrical failure: Icom handheld to communicate, 396 to navigate
TOTAL Power failure: windshield to find something soft to hit
TOTAL Structural failure: picture of my butt to kiss goodbye
Message 5
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| Subject: | RE: rivets working |
Jack,
A riveting story with a moral. It scares me to think about it.
even
though I don=92t expect it to be in salt water I don=92t like the
dissimilar
metals thing.
Thanks,
Keith
Do not archive
_____
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Jack Hilditch
Sent: Tuesday, September 30, 2008 8:38 AM
Subject: RE: RV-List: RE: rivets working
Hi Keith,
I don=92t really have a specific suggestion on replacement strategy
which is
what led me to the engineering tips list in the first place. I was
looking
for references on =91wet=92 rivet replacement. I would suggest posting
your
question to that list so we can all benefit from what that wealth of
knowledge might be able to give us. I do, however, have a story on why I
think this is such an important topic, particularly to those of us who
build
and fly our own creations.
I spent quite a few years racing sailboats, primarily in salt water
environments. Most masts and more than a few hulls at the time were
aluminum
while hardware (fairleads, turning buckles, screws, etc.) were either
stainless or bronze. Mechanically fastening dissimilar metals in a
saline
environment is, in essence, creating a battery. What happens then is
the
least noble metal becomes sacrificial and aluminum was almost always the
=91sacrificial lamb.=92 In other words, aluminum surrendered its
structural
properties and turned to aluminum oxide. Periodically (at least once
every
year in those days) we would pull masts out of the boats to remove all
rigging and fasteners. Aluminum oxide, a white powder, would be present
everywhere dissimilar metals came into contact. We tried many and
varied
electrostatic barrier coatings to minimize the electrolysis but none of
them
provided a 100% solution. We knew we had a problem but those old
=91gotchas=92
of time, technology, costs and schedules demanded we stick with a
solution
we knew would allow us to at least stay within a predictable
serviceability
matrix through constant maintenance. Was it ideal? Absolutely not, but
it
was what we had to work with at the time.
It really got our attention, at one point in the late 1970=92s, when a
mast-mounted halyard reel winch on a sixty-foot sailboat, under shear
load
in the vicinity of 6000+ lbs, was incorrectly fed its 3/8=94 7x19
galvanized
halyard cable. The cable imparted a =91racking=92 or fulcrum force to
the winch
thereby putting its upper SS fasteners into compression and its lower SS
fasteners into tension. These fasteners had quietly built up a
significant
barrier coat of aluminum oxide between them and the aluminum mast due to
an
errant electrical current being introduced elsewhere in the (also)
aluminum
hull, nowhere near the mast-mounted winch. The result was the lower SS
winch
fasteners pulled out of the mast under load and the winch tore off the
mast
with great force. The modulus of elasticity in the galvanized halyard
cable
allowed it to store significant energy which it then used to propel a
50+ lb
winch upward into the face of the deckhand operating it. The result was
a
broken jaw, several lost teeth, several other facial bones broken, a
concussion and a (this is not a drill) man overboard exercise at sea. It
caught our attention without any doubt. It also pointed out to us that
even
when you run regular, scheduled and thorough maintenance schedules,
unexpected elements creep in.
We eventually traced the errant electrical current to a corroded bonding
strap on a sacrificial anode attached to a through-hull fitting. That
missing anode allowed current from another boat in the marina to enter
our
hull through an unprotected conduit making the entire boat and rig into
an
active battery. We found considerably more electrolysis than normal
during
the immediately scheduled haul out. It was everywhere and had weakened a
number of fastening points where stainless met aluminum.
This is a long-winded way to say I=92m a true believer and have great
respect
for making sure mechanical fastenings in an aluminum structure are
properly
done, regularly maintained and constantly inspected, particularly when
it is
my butt sitting in the aircraft at altitude.
Regards,
Jack
Checked by AVG.
9/29/2008
7:25 PM
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