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Atttude indicator removal


scott poms

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Glare shield should come off at which point you will have access to the instruments from above. Many glare shields are held on with a sheet metal screw on the left and right top of the glare shield. Use caution when removing the screws so you do not scratch up your windscreen with the screwdriver you use or your watch, ring, etc. If you have glare shield lights, be sure to disconnect them before you try to completely extract the glare shield. Connector should be on the right hand side of the panel, if it is similar to my J.

Like Davarron said, my mechanic could probably have removed mine from the bottom, as he knows how much "stretch" is allowable in the wiring and tubing, but I am less confident in my ability to not cause more damage than I am repairing.

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54 minutes ago, scott poms said:

Yes removed glare shield and no problem. Did need to unbolt compass to lift shield out.  Hoses very difficult to remove but got them off.  Was rebuilt 4 years ago, seems installer used teflon tape on fittings, is that normal procedure? 

Teflon tape is a great way to destroy gyros and vacuum pumps.  When the fitting is installed, the threads cut the tape into fragments which can find their way to undesirable locations.  You can get away with it if they are away from the end, but then it is also not very effective.  Best not to use it.  The other hazard is the hoses.  Especially when reusing them after previous clamping pressure, the insides can "roll" off or flake off on reinstallation and cause similar problems.  It is particularly disappointing to lose a new pump or gyro due to FOD created by the reassembly process.  Check the ends of hoses to be sure they are clean and not flaking.  Replace if brittle or flaking in any way.

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This explains why and how friable Teflon tape is.

 

Teflon tape is interesting stuff...

1) high temperature resistance.

2) highly non-reactive or soluble

3) soft and compressible 

4) really low tensile strength 

 

It is made using some pretty uncommon processes....

1) it's melting temperature and degradation temperatures are close together.  Using the typical polymer molding processes are out.

2) fine powdered PTFE is sintered into large rolls.  Sintering compresses the powders and glues them together using less temperature than the degradation T.  Picture using sublimation, only with Teflon molecules... ?

3) The strength between molecules that have been sintered is not very strong.

4) the large roll of sintered Teflon is then placed on a skiving machine.  Sort of like a giant and very precise lathe.

5) the outer layer is shaved off as the roll turns, while being trimmed with a slitting machined to a proper width, and then wound up on small rolls down stream...

 

 

Rob has explained the importance of keeping the tape from the end threads.  There is probably additional guidance on how much tape to use, and how much tension to use, and what direction to wrap the threads... and of course, how to finish or cut off the tape.

It's been a while since I was trained on this stuff... this is not typical PP knowledge.... :)

Some of my old memories are better than my new memories...!

Best regards,

-a-

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Vibration and adjacent work will kill instruments as well.  I have seen someone cutting new holes in the panel with instruments installed causing some rapid failures in gyros.  The failures usually occur about the time that you forgot about such work. 

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5 hours ago, carusoam said:

This explains why and how friable Teflon tape is.

 

Teflon tape is interesting stuff...

1) high temperature resistance.

2) highly non-reactive or soluble

3) soft and compressible 

4) really low tensile strength 

 

It is made using some pretty uncommon processes....

1) it's melting temperature and degradation temperatures are close together.  Using the typical polymer molding processes are out.

2) fine powdered PTFE is sintered into large rolls.  Sintering compresses the powders and glues them together using less temperature than the degradation T.  Picture using sublimation, only with Teflon molecules... ?

3) The strength between molecules that have been sintered is not very strong.

4) the large roll of sintered Teflon is then placed on a skiving machine.  Sort of like a giant and very precise lathe.

5) the outer layer is shaved off as the roll turns, while being trimmed with a slitting machined to a proper width, and then wound up on small rolls down stream...

 

 

Rob has explained the importance of keeping the tape from the end threads.  There is probably additional guidance on how much tape to use, and how much tension to use, and what direction to wrap the threads... and of course, how to finish or cut off the tape.

It's been a while since I was trained on this stuff... this is not typical PP knowledge.... :)

Some of my old memories are better than my new memories...!

Best regards,

-a-

Dang! This is weird. While reading this, I had a vision of the professor from Gillian's island working on something in his makeshift lab complete with bamboo beakers and palm frond driven generator. Of course now that I brought it up It begs the question....

Maryanne or Ginger? What say you Mooneyspacers?

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