Today's Message Index:
----------------------
1. 01:18 AM - Re: Questions on new IA test (FLYaDIVE)
2. 11:53 AM - Re: Questions on new IA test (Gary Vogt)
3. 03:44 PM - Re: Questions on new IA test (FLYaDIVE)
4. 06:31 PM - High CHTs Epilogue (Mark T. Mueller)
5. 09:52 PM - Re: High CHTs Epilogue (Gary L Vogt)
Message 1
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| Subject: | Re: Questions on new IA test |
Gary:
The real answer is (d) NONE OF THE ABOVE.
The only way to prevent oxidation from forming is to REMOVE oxygen from
contacting the aluminum. When oxygen contacts bare aluminum Aluminum oxide
is formed. As the aluminum oxide builds up the thickness of the aluminum
oxide becomes thick enough to PREVENT oxygen from contacting the aluminum.
Once the oxygen is no longer contacting the aluminum the oxidation stops.
Most aluminum's are Clear Coat Anodized as the last process in their
production as anodizing prevents oxygen form contacting the aluminum.
The problem is: The aluminum oxide is so very soft and so very thin that a
fingernail can cut through it. So, ANY abrasion, especially metal to
metal abrasion will constantly be removing the oxide - Which is a
protective coating. And allowing new oxides to form. The oxides form at
the cost of metal thickness. What I would question in
the expiation provided: Is the aluminum oxide hard enough to act as an
abrasive or is the bond between the aluminum and aluminum oxide so poor
that the oxide is removed re-starting the process all over again?
NOW! To further complicate (muck up the waters) the facts, aluminum oxide
is used in making grinding wheels and emery paper (sand paper). Pretty
abrasive stuff!!!
So, where does one write addressing the FAA in changing their answer?
Fretting causes abrasion.
Abrasion causes everything else.
Barry
On Fri, Apr 20, 2012 at 2:00 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
> Q: Fretting is a major cause of aircraft repairs. What does fretting
> cause?
>
> A(a): Prevents aluminum oxides from forming
>
> A(b): Allows moisture to be trapped between the metals
>
> A(c): Allows oxidation to form between the metals
>
> ------------
>
> I picked: a)
>
> Their answer: c)
>
> -------------
>
> Their logic:
>
> Fretting corrosion occurs at the interface of two highly-loaded surfaces
> that are not supposed to move against one another. When vibration causes
> the surfaces to rub together the protective oxide film is rubbed off and
> the oxides act as abrasives increasing the amount of damage and preventing
> new oxides from forming on the surface.
>
> --------------
> Note: "When vibration causes the surfaces to rub together the protective
> oxide film is rubbed off . . . . preventing new oxides from forming on the
> surface"
>
> They are clearly wrong.
>
> *
>
> *
>
>
Message 2
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| Subject: | Re: Questions on new IA test |
The problem is: -The aluminum oxide is so very soft and so very thin that
a fingernail can cut through it. -So, ANY abrasion, especially metal to
metal-abrasion-will constantly be removing the oxide - Which is a prote
ctive coating.-=0A=0A=0Ahense: the answer is: - a)=0A=0A=0A____________
____________________=0A From: FLYaDIVE <flyadive@gmail.com>=0ATo: teamgrumm
an-list@matronics.com =0ASent: Saturday, April 21, 2012 1:16 AM=0ASubject:
Re: TeamGrumman-List: Questions on new IA test=0A =0A=0AGary:=0AThe real an
swer is (d) NONE OF THE ABOVE.=0A=0AThe only way to prevent oxidation from
forming is to REMOVE oxygen from contacting the aluminum. -When oxygen co
ntacts bare aluminum Aluminum oxide is formed. -As the aluminum oxide bui
lds up the thickness of the aluminum oxide becomes thick enough to PREVENT
oxygen from contacting the aluminum. -Once the oxygen is no longer contac
ting the aluminum the oxidation stops. -Most-aluminum's are Clear Coat
Anodized as the last process in their production as anodizing prevents oxyg
en form contacting the aluminum.=0A=0AThe problem is: -The aluminum oxide
is so very soft and so very thin that a fingernail can cut through it. -
So, ANY abrasion, especially metal to metal-abrasion-will constantly be
removing the oxide - Which is a protective coating. -And allowing new ox
ides to form. -The oxides form at the cost of metal thickness. -What I
would question in the-expiation-provided: -Is the aluminum oxide hard
enough to act as an abrasive or is the bond between the aluminum and alumi
num oxide so poor that the oxide is removed re-starting the process all ove
r again?=0ANOW! -To further complicate (muck up the waters) the facts, al
uminum oxide is used in making grinding wheels and emery paper (sand paper)
. -Pretty abrasive stuff!!!=0A=0ASo, where does one write addressing the
FAA in changing their answer?=0A=0AFretting causes abrasion.=0AAbrasion cau
ses everything else.=0A=0ABarry=0A=0A=0A=0A--=0A=0AOn Fri, Apr 20, 2012
at 2:00 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:=0A=0AQ: -Fretting i
s a major cause of aircraft repairs. What does fretting cause?-=0A>=0A>
=0A>A(a): -Prevents aluminum oxides from forming=0A>=0A>=0A>A(b): -Allo
ws moisture to be trapped between the metals=0A>=0A>=0A>A(c): -Allows oxi
dation to form between the metals=0A>=0A>=0A>------------=0A>=0A>=0A>I pick
ed: - a)=0A>=0A>=0A>Their answer: -c)=0A>=0A>=0A>-------------=0A>=0A>
=0A>Their logic:-=0A>=0A>=0A>Fretting corrosion occurs at the interface o
f two highly-loaded surfaces that are not supposed to move against one anot
her. When vibration causes the surfaces to rub together the protective oxid
e film is rubbed off and the oxides act as abrasives increasing the amount
of damage and preventing new oxides from forming on the surface.-=0A>=0A>
=0A>--------------=0A>Note: -"When vibration causes the surfaces to rub t
ogether the protective oxide film is rubbed off . . . .-preventing new ox
ides from forming on the surface"=0A>=0A>=0A>They are clearly wrong. -=0A
>st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
=0Atp://forums.matronics.com=0A_blank">http://www.matronics.com/contributio
=====================
Message 3
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| Subject: | Re: Questions on new IA test |
Nope! The aluminum oxide DOES form. It just gets removed as quickly as it
forms.
As I stated: "So, ANY abrasion, especially metal to metal abrasion will
constantly be removing the oxide - Which is a protective coating." As long
as Oxygen is in contact with aluminum you will have the formation of
aluminum oxide.
I know this a little bit difficult to get one's head wrapped around. It is
a bit of an English lesson with semantics. And a bit like
the proverbial question which came first: The chicken or the egg?
But, the question is really: What answer does the FAA want?
Personally; I'll be satisfied with a 98% on the test and leave that
question blank for them to ponder.
Barry
On Sat, Apr 21, 2012 at 2:52 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
> The problem is: The aluminum oxide is so very soft and so very thin that
> a fingernail can cut through it. So, ANY abrasion, especially metal to
> metal abrasion will constantly be removing the oxide - Which is a
> protective coating.
>
> hense: the answer is: a)
>
> ------------------------------
> *From:* FLYaDIVE <flyadive@gmail.com>
> *To:* teamgrumman-list@matronics.com
> *Sent:* Saturday, April 21, 2012 1:16 AM
> *Subject:* Re: TeamGrumman-List: Questions on new IA test
>
> Gary:
>
> The real answer is (d) NONE OF THE ABOVE.
>
> The only way to prevent oxidation from forming is to REMOVE oxygen from
> contacting the aluminum. When oxygen contacts bare aluminum Aluminum oxide
> is formed. As the aluminum oxide builds up the thickness of the aluminum
> oxide becomes thick enough to PREVENT oxygen from contacting the aluminum.
> Once the oxygen is no longer contacting the aluminum the oxidation stops.
> Most aluminum's are Clear Coat Anodized as the last process in their
> production as anodizing prevents oxygen form contacting the aluminum.
>
> The problem is: The aluminum oxide is so very soft and so very thin that
> a fingernail can cut through it. So, ANY abrasion, especially metal to
> metal abrasion will constantly be removing the oxide - Which is a
> protective coating. And allowing new oxides to form. The oxides form at
> the cost of metal thickness. What I would question in
> the expiation provided: Is the aluminum oxide hard enough to act as an
> abrasive or is the bond between the aluminum and aluminum oxide so poor
> that the oxide is removed re-starting the process all over again?
> NOW! To further complicate (muck up the waters) the facts, aluminum oxide
> is used in making grinding wheels and emery paper (sand paper). Pretty
> abrasive stuff!!!
>
> So, where does one write addressing the FAA in changing their answer?
>
> Fretting causes abrasion.
> Abrasion causes everything else.
>
> Barry
>
>
> On Fri, Apr 20, 2012 at 2:00 PM, Gary Vogt <teamgrumman@yahoo.com> wrote:
>
> Q: Fretting is a major cause of aircraft repairs. What does fretting
> cause?
>
> A(a): Prevents aluminum oxides from forming
>
> A(b): Allows moisture to be trapped between the metals
>
> A(c): Allows oxidation to form between the metals
>
> ------------
>
> I picked: a)
>
> Their answer: c)
>
> -------------
>
> Their logic:
>
> Fretting corrosion occurs at the interface of two highly-loaded surfaces
> that are not supposed to move against one another. When vibration causes
> the surfaces to rub together the protective oxide film is rubbed off and
> the oxides act as abrasives increasing the amount of damage and preventing
> new oxides from forming on the surface.
>
> --------------
> Note: "When vibration causes the surfaces to rub together the protective
> oxide film is rubbed off . . . . preventing new oxides from forming on the
> surface"
>
> They are clearly wrong.
>
> *
>
> st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
> *
>
>
> *
>
> *
>
> *
>
> *
>
>
Message 4
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| Subject: | High CHTs Epilogue |
A few weeks ago I asked for advice/comments on high CHTs after my annual
inspection. I appreciate the responses I got back, and most concentrated
on baffling and timing.
My IA swore the timing on the engine was correct, and the cabin heating
duct in front of the exit ramp would not effect cooling flow much. Spent a
day trying to troubleshoot, and he became convinced it was an
instrumentation issue. Kind of made sense, but I was skeptical. He did
find one of the CHT probes had significant tip wear (they were well over 10
years old...)
After new probe installation, the monitor indicated a 10 degree drop in
CHTs, but still running well over 430 in cruise...
Last weekend, I re-routed the heater duct away and around the exit ramps.
A pain, but just took some time and extra materials. Noticed an immediate
improvement in cooling, but CHTs were still too high for my liking.
I ordered a Mag-Rite timing tool kit from ATS. Digital protractor and
nylon cylinder probe to enable very precise location of actual TDC (as
opposed to a mark on a ring and location on case.) Can't say enough good
things about this kit (worth every penny), very easy to use, and the
digital protractor has 1/10 degree resolution. Re-timed my mags (I have a
LASAR ignition) to specs. To say the timing was 'off' is an
understatement. It was WAY off. The smoothness of the LASAR masked the
issue well, and the motor put out good power.
Now that it is 'dialed in' to within a tenth of a degree of accuracy, the
CHTs dropped over 20F.
So, I improved cooling air flow, and fixed my timing. This is AFTER paying
an IA for a complete annual, and coming back for troubleshooting.
At the end of the day, the lesson I learned is after over 10 years of
ownership, I will know when 33R is "dialed in" or not regardless of what an
IA may believe even if he has been taking care of this aircraft for several
years...
Mark
Message 5
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| Subject: | Re: High CHTs Epilogue |
Mark,
That's good to hear. When my plane is "dialed in" it will still run 410 stra
ight and level at 4000 feet. Can't wait to get the IO360 on and finished.
Gary
Sent from my iPad
On Apr 21, 2012, at 6:30 PM, "Mark T. Mueller" <mark.t.mueller@comcast.net> w
rote:
> A few weeks ago I asked for advice/comments on high CHTs after my annual i
nspection. I appreciate the responses I got back, and most concentrated on b
affling and timing.
>
> My IA swore the timing on the engine was correct, and the cabin heating du
ct in front of the exit ramp would not effect cooling flow much. Spent a da
y trying to troubleshoot, and he became convinced it was an instrumentation i
ssue. Kind of made sense, but I was skeptical. He did find one of the CHT p
robes had significant tip wear (they were well over 10 years old...)
>
> After new probe installation, the monitor indicated a 10 degree drop in CH
Ts, but still running well over 430 in cruise...
>
> Last weekend, I re-routed the heater duct away and around the exit ramps.
A pain, but just took some time and extra materials. Noticed an immediate i
mprovement in cooling, but CHTs were still too high for my liking.
>
> I ordered a Mag-Rite timing tool kit from ATS. Digital protractor and nyl
on cylinder probe to enable very precise location of actual TDC (as opposed t
o a mark on a ring and location on case.) Can't say enough good things abou
t this kit (worth every penny), very easy to use, and the digital protractor
has 1/10 degree resolution. Re-timed my mags (I have a LASAR ignition) to s
pecs. To say the timing was 'off' is an understatement. It was WAY off. T
he smoothness of the LASAR masked the issue well, and the motor put out good
power.
>
> Now that it is 'dialed in' to within a tenth of a degree of accuracy, the C
HTs dropped over 20F.
>
> So, I improved cooling air flow, and fixed my timing. This is AFTER payin
g an IA for a complete annual, and coming back for troubleshooting.
>
> At the end of the day, the lesson I learned is after over 10 years of owne
rship, I will know when 33R is "dialed in" or not regardless of what an IA m
ay believe even if he has been taking care of this aircraft for several year
s...
>
> Mark
>
>
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