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Polishing Windshield


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22 minutes ago, M20Doc said:

We’ve had good luck polishing aircraft windows with 2 different kits from Spruce.  These combined with a small angle drill worked on the inside with the glare shield removed for better access.  My suggestion is no headsets, clipboards, charts etc. on the glareshield to avoid scratches.

https://www.aircraftspruce.ca/catalog/cspages/scratchoff.php

https://www.aircraftspruce.ca/catalog/cspages/windshieldrestor.php

Thanks guys, that’s helpful.  I’m gonna keep doing some research and try to wait for @Skates97 pics and experience.  It seems like it should be easy, but I think it’s a lot harder than it looks and it’s something that can easily be permanently screwed up with a good bit of $$ and time to put in a new one.

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There are plenty of pics of MSers replacing side windows around here...

Lots of work from removing the old sealant to cutting, drilling and re sealing... and fixing the interior plastic that has cracks...

The way to get a feel for the job... is to start with one window... the door makes a great project that is hard to get in too far over your head...

Side windows are an owner maintenance job... Windshields are not on the list...

It is good to have a relationship with your mechanic... it helps to have advice, tools, support for all the other things that crop up... like that roll pin that holds the door handle on...

PP thoughts only, my C got a new window this way... before MS was available...

Best regards,

-a-

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Before attempting restoration, I would carefully clean and dry the window carefully.  Many of the polishing kits will do a good job without resorting to using sand paper.  
It’s easier to start with polish and move backwards to something coarser if needed than to start with the coarse materials and work to finer polish.

Clarence

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9 hours ago, carusoam said:

Side windows are an owner maintenance job... Windshields are not on the list...

It doesn’t need to be on that list for it to be ok for an owner to do the work. That list is not all inclusive and is exemplary only. The coleal interpretation from the FAA explains this.

https://www.aopa.org/news-and-media/all-news/2019/october/pilot/savvy-aviator-preventive-maintenance

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Replacing side windows is specifically-approved owner maintenance; replacing windshields is specifically-unapproved for owner maintenance. 

Nothing is mentioned about cleaning and buffing. Be careful with power buffers/sanders on the windshield, it can be an expensive "oops"!

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1 hour ago, dzeleski said:

It doesn’t need to be on that list for it to be ok for an owner to do the work. That list is not all inclusive and is exemplary only. The coleal interpretation from the FAA explains this.

https://www.aopa.org/news-and-media/all-news/2019/october/pilot/savvy-aviator-preventive-maintenance

True, but in the case of a windshield, drilling out rivets and replacing them would likely be considered a complex assembly operation which falls outside preventive maintenance by Part 43 definition.

28 minutes ago, Hank said:

Replacing side windows is specifically-approved owner maintenance; replacing windshields is specifically-unapproved for owner maintenance. 

I don’t see where it is “specifically-unapproved.” However, based on the fact that side windows are listed in Appendix A and windshields are not, and also based on the “complex assembly” required, I agree it would be difficult to argue that it is preventive. One could always do it under supervision.

Skip

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2 hours ago, dzeleski said:

It doesn’t need to be on that list for it to be ok for an owner to do the work. That list is not all inclusive and is exemplary only. The coleal interpretation from the FAA explains this.

https://www.aopa.org/news-and-media/all-news/2019/october/pilot/savvy-aviator-preventive-maintenance

Thanks for supplying the Coleal interpretation... Based on a pilot being able to measure tire pressure in a Lear 60....

We can use that to prove to ourselves four things...

1) The task is not on the official 31 list... but similar.  Windshield... not on the list... but maybe similar to a side window... next.

2) No more difficult.   Hmmmm... 3D fitting of formed acrylic vs. 2D fitting of a flat window... hmmm a bit more difficult...

3) No more complex.  Sheet metal work to complete the install vs. no sheet metal work... Hmmm a bit more complex with skills I don’t have from any shop class decades ago...

4) No more risky.  A broken windshield at cruise speed vs. a side window... given the option, I’d take the side window over the windshield... hmmm...  Using fear as a measure of how different the windshield is vs. side window... there is a difference.

 

 

The AOPA discussion uses this summary...

“You get the idea. Given what the FAA said in the Coleal letter, if you do something not on the list that’s similar to something that is on the list and no more difficult, complex, or risky, you have an FAA letter of interpretation to point to should your action ever be challenged. Contrary to conventional wisdom—which might have been valid prior to 2009 but no longer is—you’re not limited to the 31 items on the list.“


5) The problems with acrylic... a small crack initiator can be the start of a larger crack propagation.... stress multipliers are more present in 3D structures than flat surfaces...

6) Nothing like 200mph winds on the windshield to add force to the crack propagation...

I think Mr. Coleal did a pretty good job of explaining that a pilot can do a pretty important job like checking the 219psi tire pressure every day as required...

But, I’m pretty sure he didn’t mean that same pilot will swapping out the Lear’s windshield later the same day...

For that... he is going to want to have a good working relationship with his A&P to do the work as an owner that is supervised by the A&P.

Great thought experiment... let me know what I missed... :)

PP interpretation of the Coleal letter, not a mechanic or lawyer...

Best regards,

-a-

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Fun reasoning regarding use of power tools and buffing acrylic....

1) The softening temperature Of acrylic is just over the boiling point of water....

2) Frictional heating is pretty good at heating things up locally...

3) If you soften the surface by heating it... you ruin the work you are trying to get done...

4) The advantage of wet processes... better temperature control while removing the excess materials...

5) There is probably a lot of advice to keep cleaning things and refreshing work towels... any contamination from sand paper or acrylic dust can set you back...

 

PP thoughts only, not a mechanic...

Best regards,

-a-

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8 hours ago, carusoam said:

For that... he is going to want to have a good working relationship with his A&P to do the work as an owner that is supervised by the A&P.

Great thought experiment... let me know what I missed... :)

PP interpretation of the Coleal letter, not a mechanic or lawyer...

Best regards,

-a-

My point wasnt that we should be swapping windshields. My point was more around just because its not on that list doesnt mean we cant do it. As an example I pulled my Gami injectors and shipped them off to get serviced and adjusted, its not on the list but I think anyone that has turned a wrench for a few years can manage a couple injectors.

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Full scale of gray... with some things...

Some mechanics have failed to orient the FIs properly, you know the tiny vent hole location? (Fire risk)

Others have lost the order the GAMI injectors were installed in... (annoyance)

 

Is there a method of deciding what is right for owner replaced parts?

I assume I would need the proper maintenance manual and tools and possibly some training the first time...

 

Some people around here own mechanic shops for industrial trucks, Sport utes, and other vehicles... they are fully capable of doing things that are best done by other people...

 

Or would I be good to go watching a YouTube video like I would be for my Chevy..?

 

Sounds like I might be in a tough spot... if I watch an EAA video about timing my mags, and go perform that myself...

My risk starts to increase this way...

To lessen my risk... I start classes to obtain my A&P license... :)

 

If I goof up a spark plug install... and it stops working... there is another one in the cylinder... low harm / no foul...

If I goof up torquing down my fuel injector because my torque settings haven’t been calibrated... there isn’t another FI in the cylinder to cover my maintenance induced failure...

Sounds like lots of opportunity to accidentally add risk to things...

 

I would love to see pulling and cleaning fuel injectors added to the list of things I can do without supervision...

The baby food jar test would be a popular sport for MSers with FI... 

There is probably a list of 31 other skills that people can be trained on that would be beneficial...

 

Or are we discussing taking things off, and having a mechanic put them back on...?

Looks like we may need a separate thread on the expansion of Owner maintenance related to the Coleal letter...

Imagine the discussion...

MSC vs. Mooney mechanic vs. non-Mooney A&P vs. Owner mechanic....  all things are possible. :)
 

Anyone with a wrench can loosen and tighten a V-band clamp on and exhaust system... what prevents an owner from doing this a couple of times until he gets it right? What is the cost of him doing this?

PP thoughts only, not a mechanic...

Best regards,

-a-

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2 hours ago, dzeleski said:

My point wasnt that we should be swapping windshields. My point was more around just because its not on that list doesnt mean we cant do it. As an example I pulled my Gami injectors and shipped them off to get serviced and adjusted, its not on the list but I think anyone that has turned a wrench for a few years can manage a couple injectors.

I've pulled the injectors out to clean them, which is more complicated than inspecting the lines and clamps to comply with the Lycoming AD. But silly FAA makes me get the lines inspected by an A&P because required inspections are defined as maintenance and not preventive maintenance.

Skip

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3 hours ago, carusoam said:

Anyone with a wrench can loosen and tighten a V-band clamp on and exhaust system... what prevents an owner from doing this a couple of times until he gets it right? What is the cost of him doing this?

The problem with that is if it’s a turbo V band and you don’t get it right the first time, you might not get a second chance. 

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Hey Anthony @carusoam, since we've drifted off in the weeds anyway, what are your thoughts on old ABS? It seems easy to solvent weld ABS and even patch things up with a little glass cloth and solvent-liquefied resin, but doesn't the stuff lose plasticity over time? Just wondering why my glareshield keeps cracking (other than it's a terrible design-- too thin, lots of small radius bends and requires a lot of flexing for installation and removal).

Skip

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The surface of the old ABS is the first part to suffer... lots of Styrene that is UV sensitive and turns brown-ish...

The polymer chain of ABS...

  • butadiene (a rubber for impact resistance)
  • styrene (nice polymer to form, terrible impact, or aging)
  • Acrylonitrile (nice backbone to mount the other’s physical properties to)

 

Unfortunately, the ABS plastic sheet is so thin to begin with, it is mostly surface... :) (figuratively speaking)

When formed, drawn into a mold, or stretched over a mandrel, it gets even thinner...

Heat cycles are hazardous to the polymer material as well...

  • Mixing with colors and additives... is a high heat cycle
  • Extruding into a sheet... another hot period of time
  • Thermoforming the sheet into a finished shape... has thermo right in the name!

 

So the years go by... oxidation and UV light take their toll...

The material will continue to get more brittle...

Each time it gets flexed, another crack will form...

We are kind of left with the original shape in a brittle form...

Speaking of temperature affects.... the colder the plastic parts are, the less they like flexing.... so pick a warm day if you have take panels in and out of the plane...

Last ditch efforts include...

  • Structural support from behind... fiberglass and resin
  • Filling in the outer surface cracks or broken parts... solvent and ABS pellets or old pieces blended together to form a paste...
  • Paint over the whole thing using an ABS compliant paint....
  • Or the real fancy solution... Stretchy Euro-fabric stretched all over it....

The Euro-fabric idea came new from the factory in 1994... it still looks pretty good today...

Often, it is important to check the chemical compatibility of all the plastics with paints and solvents and glass resins...

There are many threads around here detailing the prior art people have been successful with...

The one thing we haven’t solved... extending the life of some of the older plastics in our planes... their molecular weight is getting shorter as the molecules cleave due to damage...

When it comes to replacements there have been a few threads that have touched that subject...

Wonder what the experimental guys are doing for theirs...

 

Wish I had better news...

Best regards,

-a-

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While reviewing my scribbling...

I realize Skip’s glare shield may be similar to my own... both born the same year.

Mine doesn’t come off very often... lives indoors...

If it is breaking down, I don’t know it because we don’t touch it to find out...   :)

Got any pics?

Mine may be different with the compass mounted on the top, not on the tube...

Different because it is an O?

Best regards,

-a-

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1 hour ago, PT20J said:

Hey Anthony @carusoam, since we've drifted off in the weeds anyway, what are your thoughts on old ABS? It seems easy to solvent weld ABS and even patch things up with a little glass cloth and solvent-liquefied resin, but doesn't the stuff lose plasticity over time? Just wondering why my glareshield keeps cracking (other than it's a terrible design-- too thin, lots of small radius bends and requires a lot of flexing for installation and removal).

Skip

I don’t think that’s thread drift at all, one of my worst scratches is on the inside, right where the glare shield contacts the windscreen when installing it.  Getting the glare shield in/out is like playing chicken... I’ve got to bend the 50 year old glare shield enough to install/remove it without scratching the windscreen, but not so much that I snap it in half.  Couldn’t they have designed a 2 piece glare shield?!

Anyway, I’m not even worried about that scratch.  If I fixed it, I guarantee I’d hit it again with the glare shied.  

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59 minutes ago, Ragsf15e said:

I don’t think that’s thread drift at all, one of my worst scratches is on the inside, right where the glare shield contacts the windscreen when installing it.  Getting the glare shield in/out is like playing chicken... I’ve got to bend the 50 year old glare shield enough to install/remove it without scratching the windscreen, but not so much that I snap it in half.  Couldn’t they have designed a 2 piece glare shield?!

Anyway, I’m not even worried about that scratch.  If I fixed it, I guarantee I’d hit it again with the glare shied.  

Put Teflon tape around the edges of the glare shield.

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2 hours ago, carusoam said:

The surface of the old ABS is the first part to suffer... lots of Styrene that is UV sensitive and turns brown-ish...

The polymer chain of ABS...

  • butadiene (a rubber for impact resistance)
  • styrene (nice polymer to form, terrible impact, or aging)
  • Acrylonitrile (nice backbone to mount the other’s physical properties to)

 

Unfortunately, the ABS plastic sheet is so thin to begin with, it is mostly surface... :) (figuratively speaking)

When formed, drawn into a mold, or stretched over a mandrel, it gets even thinner...

Heat cycles are hazardous to the polymer material as well...

  • Mixing with colors and additives... is a high heat cycle
  • Extruding into a sheet... another hot period of time
  • Thermoforming the sheet into a finished shape... has thermo right in the name!

 

So the years go by... oxidation and UV light take their toll...

The material will continue to get more brittle...

Each time it gets flexed, another crack will form...

We are kind of left with the original shape in a brittle form...

Speaking of temperature affects.... the colder the plastic parts are, the less they like flexing.... so pick a warm day if you have take panels in and out of the plane...

Last ditch efforts include...

  • Structural support from behind... fiberglass and resin
  • Filling in the outer surface cracks or broken parts... solvent and ABS pellets or old pieces blended together to form a paste...
  • Paint over the whole thing using an ABS compliant paint....
  • Or the real fancy solution... Stretchy Euro-fabric stretched all over it....

The Euro-fabric idea came new from the factory in 1994... it still looks pretty good today...

Often, it is important to check the chemical compatibility of all the plastics with paints and solvents and glass resins...

There are many threads around here detailing the prior art people have been successful with...

The one thing we haven’t solved... extending the life of some of the older plastics in our planes... their molecular weight is getting shorter as the molecules cleave due to damage...

When it comes to replacements there have been a few threads that have touched that subject...

Wonder what the experimental guys are doing for theirs...

 

Wish I had better news...

Best regards,

-a-

Actually mine isn't all that bad for a 25 year old piece of thin black plastic --  probably because it has spent most of it's life in a hangar. When I bought it, there was one crack. When I had it off, I noticed that someone had done some work on it and the light strip was assembled backwards, so I took the two mating pieces apart and fixed the lights and also took the time to fix the big crack and reinforce some areas. I reinforced the areas that need to flex with fiberglass cloth and abs cement. The big crack was around the area in the center where the post comes through and I doubled that with some ABS sheet since it doesn't need to flex. I cut out the center to make it easier to remove from around the post and installed one of Bruce Jaegar's easy out plates. All was well until I parked it in the heat of Texas at MooneyMax where the black metal easy out plate got so hot it softened the plastic. I have since glued a thin insulating layer of dense black foam rubber to the bottom of the plate to insulate it. I need to do a little filling and sanding and fix a couple of small cracks and it should be fine. I was going to spray texture it and paint it with black SEM. But, I'm thinking a better solution might be to send it to Hector and have him cover it. 

So, what do you think, would covering it protect the plastic and hide any small cracks that develop, or would it accelerate the deterioration?

Skip

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One challenge we have...

People like their dark glare shields...

Dark absorbs heat and is detrimental to the polymers...

Most of my cars have done away with dark colors over the years...

I have had one dark leather interior... it is always a gamble of how hot the seats are going to be...

Heat is tough on polyurethane foams as well...

What would happen if you selected a lighter color for the glare shield?

I have a few things that came through the shop at aero comfort... like the fancy yokes...

It might be the fancy glare shield might be Hector’s work as well...  :)

If you are happy with the structural improvements... a surface covering might be perfect for the next steps...

Euro-cloth and euro-leather I believe are brand names for thin stretchy, light weight, materials that are used for this type of application...

The aero comfort website may give some additional hints... they mention Mooney glareshield upholstery... :)

Best regards,

-a-

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9 hours ago, Ragsf15e said:

I don’t think that’s thread drift at all, one of my worst scratches is on the inside, right where the glare shield contacts the windscreen when installing it.  Getting the glare shield in/out is like playing chicken... I’ve got to bend the 50 year old glare shield enough to install/remove it without scratching the windscreen, but not so much that I snap it in half.  Couldn’t they have designed a 2 piece glare shield?!

Anyway, I’m not even worried about that scratch.  If I fixed it, I guarantee I’d hit it again with the glare shied.  

My Ovation has a 2 part glare shield and it still seems like i have to bend, contort and swear at it to get it in......might be poor technique on my part, but i have tried enough variations to get it in.  

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The question came up if anyone had used any of these products.  The better kit below that @M20Doc recommended is the one I bought before taking my plane to Oshkosh for judging.  They were essentially brand new windows, with many scratches from construction that I couldn't stand.  I used the most aggressive sanding disc for some deep scratches on the first window (pilot side, which spent a lot of time on the bench on soft towels, while fitting the door seal for pressurization).  It took A LONG TIME, working progressively finer grits, to get the scratches out just from the initial sanding.  They DID eventually come out, but I was afraid I had gotten too aggressive to start.  Proceeding to the rest of my windows, I was more comfortable with the finer grit as a start, and just simply sand on them longer.  It's really key to use the water and not allow anything to warm up.  In the end, the windows looked like new again.

Be prepared to spend a couple hours per window and follow the instructions.  I was very pleased with the results (as were the judges at Oshkosh).

Tom

https://www.aircraftspruce.ca/catalog/cspages/windshieldrestor.php

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