Polishing prop

bnt83 said:
Not sure if that's sarcasm or you have never read that STC.
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I read it....and it does require an STC....which also requires a 337 for the STC. It is "NOT" a minor alteration as the sales verbiage indicates.
 
Fearless Tower said:
...Do a search on the 170 board. There was a discussion a while back about some FSDOs tagging props that were polished/unpainted...
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That's true but some individuals from some FSDOs doesn't make it a fact. There are numerous other examples of certain individuals making up their own mis-interpretations. If a propeller manufacturer is confronted with the question their answer is invariably going to be that they didn't sell it to you like that but they really have nothing in writing that states the propeller must be in the state it was in when it came out the factory door. If they did then, as Tom said, they wouldn't be airworthy for very long.
 
Silvaire said:
That's true but some individuals from some FSDOs doesn't make it a fact. There are numerous other examples of certain individuals making up their own mis-interpretations. If a propeller manufacturer is confronted with the question their answer is invariably going to be that they didn't sell it to you like that but they really have nothing in writing that states the propeller must be in the state it was in when it came out the factory door. If they did then, as Tom said, they wouldn't be airworthy for very long.
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Are you stating the the widely publicized prohibition on polishing props that came about around 20 some years ago, holds no merit in fact with regards to legal prohibition?
 
The STC shown above covers at least 482 propellor type certificates looks like models. So again, we can install a leading edge boot as a minor, can we remove the paint and polish it or not?
 
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bnt83 said:
What STC are you looking at?

http://rgl.faa.gov/Regulatory_and_G...e99cae53986257cd700674645/$FILE/SP00582NY.pdf

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Now here's the question, why is anyone paying for the STC or inflated product cost?

According to that highlighted statement, neither are required. What that statement is is a disclaimer by the FAA that the STC is not actually required, therefore the typical engineering research was not developed. It's kind of a nifty marketing tool though, I'm kinda surprised the FAA issued it, but then, the purpose of government is to support business and profitability, mostly by protecting the insurance industry from fraudulent operations.


Years ago I walked into the FSDO with a roll of the protective film tape from 3M and asked, "Can I use this on the leading edges of the prop, wings, and tail?" He looked at the tape, "Yep, that's what it's for." End of story.
 
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Henning said:
Now here's the question, why is anyone paying for the STC or inflated product cost?

According to that highlighted statement, neither are required. What that statement is is a disclaimer by the FAA that the STC is not actually required, therefore the typical engineering research was not developed. It's kind of a nifty marketing tool though, I'm kinda surprised the FAA issued it, but then, the purpose of government is to support business and profitability, mostly by protecting the insurance industry from fraudulent operations.
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I'm betting somewhere there is a drawing of the material. This drawing is evaluated in an STC project's compliance report. Then some sort of installation instructions and ICA is written. To get PMA for the parts they needed the STC.

STC = Sales because no one can complain that it isn't an approved part.

I know of several 135 operators who won't accept anything less than STC for alterations due to company policy for example.

McFarlane also probably just gives the paperwork away with the parts.
 
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bnt83 said:
I'm betting somewhere there is a drawing of the material. This drawing is attached to the STC. To get PMA for the parts they needed the STC.

STC = Sales because no one can complain that it isn't an approved part.

I know of several 135 operators who won't accept anything less than STC for alterations due to company policy for example.

McFarlane also probably just gives the paperwork away with the parts.
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135 I can see the perceived desire to avoid, but the material from 3M has a Mil Spec designation that lists this use of the product specifically, IIRC it's even called "Leading Edge Tape". Minor things like tape and decals do not require STC approval under any standard. Under 91 private ops, even more so no one cares.

I can see how fear of regulation has developed an unnecessary market in our Barnumist economy though. :sigh:
 
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Henning said:
The sad thing is by issuing the STC, they become complicit in the scam.
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Look at repairs for minute. I've come to the conclusion that if you want (not necessarily need it) FAA approved data, all you got do is pay for it. Even the most minor repairs that were originally sent from an engineering department on an email can be followed up with an 8110-3 or 8100-9, it just costs extra. The benefit is no one can question if it is FAA approved or not. (again especially 135 drivers that are getting their records audited or an inspector issuing a C of A for something like an import).
 
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well....doesn't that make the cheese more binding? :lol:

That might be the first STC that doesn't require recording a 337. :yikes:
 
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Checkout_my_Six said:
well....doesn't that make the cheese more binding. :lol:

That might be the first STC that doesn't require recording a 337. :yikes:
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I would argue that it isn't the first STC I've seen for a minor alteration. But it is the only one I've seen with a limitation section like that.
 
They DONT TEACH THIS STUFF IN A&P SCHOOL. How many Monday thru Friday mechanics are going to dig into things like this?
 
I'm thinking about calling that ACO manager.....and having a chat about that. :D
 
bnt83 said:
I would argue that it isn't the first STC I've seen for a minor alteration. But it is the only one I've seen with a limitation section like that.
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Did the FAA, or did they not, issue the number SP00582NY If they did, did they not approve the verbiage in the STC. ??

This issue has nothing to do with polishing a prop.
 
Tom-D said:
This issue has nothing to do with polishing a prop.
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Perhaps you need to revisit your own thread about the first thing a mechanic needs to know when altering a product.
 
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bnt83 said:
Perhaps you need to revisit your own thread about the first thing a mechanic needs to know about altering a product.
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Some one has already made that decision.

Read the question again. Did the FAA approve the verbiage in the STC when they issued the STC ? If they did, they determined the change is a minor alteration and the 337 is not required.

It seems to me that it is a simple as reading the STC and believing the issuing the STC is approval.
 
Tom-D said:
Some one has already made that decision.

Read the question again. Did the FAA approve the verbiage in the STC when they issued the STC ? If they did, they determined the change is a minor alteration and the 337 is not required.

It seems to me that it is a simple as reading the STC and believing the issuing the STC is approval.
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Why are you asking a this question, because it makes no sense. :confused:

Is the removal of paint and polishing a prop minor? That's the real question isn't it? If the OEM says it needs to be painted then removing it is an alteration, right?
 
bnt83 said:
Look at repairs for minute. I've come to the conclusion that if you want (not necessarily need it) FAA approved data, all you got do is pay for it. Even the most minor repairs that were originally sent from an engineering department on an email can be followed up with an 8110-3 or 8100-9, it just costs extra. The benefit is no one can question if it is FAA approved or not. (again especially 135 drivers that are getting their records audited or an inspector issuing a C of A for something like an import).
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But here there is "0" "Approved Data" being offered, the FAA is stating bluntly and directly, even declaring so under the definition of minor alteration, none is required. All this piece of paper indicates is that you don't need permission to apply tape to your leading edges. Read the wording then read the definition for minor alteration. This STC is like our money, it has value because the person seeking it believes it has value, not because it has an intrinsic value.
 
I've put my $0.02 in and have nothing more to add. Fortunately for me, I don't own or service any aircraft with polished props. I do not have a definitive opinion on the subject either because I'm not that familiar with prop cert.

For those who say we can't polish it, I say well we can do the above work as a minor, so maybe we can polish it too.

I've seen a polished one on a 182RG around here (FSDO on the field) not that it means much.
 
Put it this way, if an FAA inspector ever questioned the tape, I could use this STC as compelling evidence that I don't need an STC. :rofl:
 
Henning said:
Put it this way, if an FAA inspector ever questioned the tape, I could use this STC as compelling evidence that I don't need an STC. :rofl:
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Next week will install a turbo encabulator using only a Service Bulletin, an AD and AMOC documented on bar napkins.
 
Tom-D said:
Some one has already made that decision.

Read the question again. Did the FAA approve the verbiage in the STC when they issued the STC ? If they did, they determined the change is a minor alteration and the 337 is not required.

It seems to me that it is a simple as reading the STC and believing the issuing the STC is approval.
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It actually goes even further. By the verbiage in use, the basically say the entire STC is not required.:lol:

If someone wants to buy the STC, fine, but it's not necessary if you just want to apply leading edge tape. Just make a note in the log book, it'll help you track how well it lasts anyway. I wonder if I can use a stick on foam block as a vortex generator on the pressure side under the same allowance? Probably not since it would improve/alter the performance.
 
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The problem with polished props: They slowly erode away when your runway ends where the salt water begins... Better to keep that last line of defense against corrosion!
 
thomasdr72 said:
The problem with polished props: They slowly erode away when your runway ends where the salt water begins... Better to keep that last line of defense against corrosion!
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No argument there.

Just for comparison there are many surfaces on turboprop and jet aircraft in which keeping them well polished is the corrosion protection scheme. Leading edges, inlets, many thrust reverser doors, window retainers etc.
 
thomasdr72 said:
The problem with polished props: They slowly erode away when your runway ends where the salt water begins... Better to keep that last line of defense against corrosion!
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Well actually, that's backwards, although polish isn't the best finish for aluminum, a nice even aluminum oxide finish is, and it also produces lower skin friction than paint.

There is no man made finish for aluminum that outperforms aluminum oxide when it comes to protecting aluminum from corrosion, and the finish is even self repairing. Lots of aluminum work boats are bare aluminum for a reason, aluminum rejects paint because aluminum oxide works like a self healing immune system. Leave it bare, wash it with vinegar every now and then to keep the finish even. That is the best way to care for aluminum if you want aluminum to last in harsh climates.
 
bnt83 said:
No argument there.

Just for comparison there are many surfaces on turboprop and jet aircraft in which keeping them well polished is the corrosion protection scheme. Leading edges, inlets, many thrust reverser doors, window retainers etc.
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That's stainless steel stuff, that's because with Stainless you want to polish off the oxidation layer because that is what allows for corrosion. All those neat color changes you see from heat? That's what allows stainless products to deteriorate, it's a layer of oxidation that disrupts the surface and allows corrosion to start.

You cannot use the same standards and rationales for treating Stainless and Aluminum surfaces, the chemistry and metallurgy between them is two different worlds. You can't even weld them with the same processes.
 
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Henning said:
That's stainless steel stuff, that's because with Stainless you want to polish off the oxidation layer because that is what allows for corrosion. All those neat color changes you see from heat? That's what allows stainless products to deteriorate, it's a layer of oxidation that disrupts the surface and allows corrosion to start.

You cannot use the same standards and rationales for treating Stainless and Aluminum surfaces, the chemistry and metallurgy between them is two different worlds. You can't even weld them with the same processes.
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Let me guess you read chapter 12 for all transport/commuter category aircraft maintenance manuals during a short career as a toilet dumper?

Kidding aside, inlets and leading edges are often polished bare aluminum, 6061-T6 Lear 20/30 series wing leading edges for example.
 
Henning said:
Are you stating the the widely publicized prohibition on polishing props that came about around 20 some years ago, holds no merit in fact with regards to legal prohibition?
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I hope not, because it would not be true. The ICA's for most props clearly state that the prop must be coated, and the coating replaced when repairs are performed. I believe some people have stripped and polished their props and then clear-coated them, and the FAA is OK with that, but if the ICA's say it must be re-coated when it is repaired such that the coating is removed, then that's what the mechanic must do in order to comply with 14 CFR 43.13(a) before returning it to service -- and the ICA for the OP's prop includes such a requirement.

Now, the fact that the ICA requires this doesn't mean the owner has to re-coat every little scratch or nick as soon as it happens. But it does mean that when the prop is repaired by a mechanic, it must be properly coated before it is returned to service. Further, I'm pretty sure that an IA must check that all ICA's are complied with when signing an annual, but I'll defer to the IA's if they say otherwise.
 
bnt83 said:
Let me guess you read chapter 12 for all transport/commuter category aircraft maintenance manuals during a short career as a toilet dumper?

Kidding aside, inlets and leading edges are often polished bare aluminum, 6061-T6 Lear 20/30 series wing leading edges for example.
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Do you believe metallurgy changes when it goes on an airplane?:dunno: polishing isn't any more effective at preventing corrosion on aluminum than leaving it bare, and the process of continued polishing erodes the metal and exposes it to further oxidation/erosion. The only function to protect aluminum polishing has is to remove corrosive residues that would etch through the oxide layer. The only thing that is better on aluminum against corrosion than nothing, is anodizing.

Why they would recommend polishing aluminum components would not be based in corrosion alone.

Stainless components you polish due to corrosion. I can't recall seeing an aluminum heated leading edge, the one have seen have been a SS alloy, but I'm sure you're more familiar with heated leading edges than I am.
 
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Henning said:
Do you believe metallurgy changes when it goes on an airplane?:dunno: polishing isn't any more effective at preventing corrosion on aluminum than leaving it bare, and the process of continued polishing erodes the metal and exposes it to further oxidation/erosion. The only function to proto aluminum polishing has is to remove corrosive residues that would etch through the oxide layer. The only thing that is better on aluminum against corrosion than nothing, is anodizing.

Why they would recommend polishing aluminum components would not be based in corrosion alone.

Stainless components you polish due to corrosion. I can't recall seeing an aluminum heated leading edge, the one have seen have been a SS alloy, but I'm sure you're more familiar with heated leading edges than I am.
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Ron Levy said:
I hope not, because it would not be true. The ICA's for most props clearly state that the prop must be coated, and the coating replaced when repairs are performed. I believe some people have stripped and polished their props and then clear-coated them, and the FAA is OK with that, but if the ICA's say it must be re-coated when it is repaired such that the coating is removed, then that's what the mechanic must do in order to comply with 14 CFR 43.13(a) before returning it to service -- and the ICA for the OP's prop includes such a requirement.

Now, the fact that the ICA requires this doesn't mean the owner has to re-coat every little scratch or nick as soon as it happens. But it does mean that when the prop is repaired by a mechanic, it must be properly coated before it is returned to service. Further, I'm pretty sure that an IA must check that all ICA's are complied with when signing an annual, but I'll defer to the IA's if they say otherwise.
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BS show it to me in writing Once again you make a mountain out of a mole hill.

OBTW we in the Field as A&Ps are not allowed to make repairs to props, all we are allowed to do is minor maintenance. So when we don't make repairs, we don't replace the finish.

Your Interpretation of the ICA thing is a totally wrong interpretation. Simply because we are not allowed to make repairs to props.
 
OBTW we in the Field as A&Ps are not allowed to make repairs to props, all we are allowed to do is minor maintenance. So when we don't make repairs, we don't replace the finish.

Blending leading edge damage isn't a repair?

How do you explain the above STC which is clearly for an alteration? Can you alter the prop?
 
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