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Questions on new IA test

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teamgrumman(at)yahoo.com
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Posted: Fri Apr 20, 2012 10:02 am Post subject: Questions on new IA test

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.  



 [quote][b]

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BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sat Apr 21, 2012 12:18 am Post subject: 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(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

 [quote] 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.  



  	  Quote: 	
		  



st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


[b]

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teamgrumman(at)yahoo.com
Guest

Posted: Sat Apr 21, 2012 10:53 am Post subject: 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 protective coating. 

hense: the answer is:   a)

        From: FLYaDIVE <flyadive(at)gmail.com>

 To: teamgrumman-list(at)matronics.com 

 Sent: Saturday, April 21, 2012 1:16 AM

 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(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

  	  Quote: 	
		   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.  

  	  Quote: 	

st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution

 [quote][b]

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BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sat Apr 21, 2012 2:44 pm Post subject: 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(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

 [quote] 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(at)gmail.com (flyadive(at)gmail.com)>

 To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com) 

  Sent: Saturday, April 21, 2012 1:16 AM

 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(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

  

 	  Quote: 	
		    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.  



 

 	  Quote: 	
		  



st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


 	


 

   

  	  Quote: 	
		  



st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	


[b]

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