Prop Clean Up

dmccormack

dmccormack

Touchdown! Greaser!
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Dan Mc
The metal Sensenich prop on my Chief has a dirty look due to what looks like a worn wax of some other coating.

I cleaned up some dark streaks with Simple green (A/C formaula) last night but would like to get the prop cleane dup a bit.

Are metal props waxed? Is there a silcone or other base glaze applied?
 
Sensenich used to have some good tips on their site for prop care - I suppose the info is still there.


Trapper John
 
dmccormack said:
Didn't find much owner-advice on that site.

I did find this product listed on Wag-aero site: http://store.wagaero.com/product_info.php?products_id=12614

Anyone have experience using Rolite?
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My memory is a little fuzzy, but what I remember is Sensenich was taking the position that polishing a prop was not good, because whatever protective coating that was on the prop would be removed, and that would cause accelerated corrosion. I don't think Sensenich was the only manufacturer taking this position, either.

Here's FAA's take on it:

Polished propeller blades are rarely an acceptable configuration. Corrosion protection such as paint and anodize should not be removed from the surface of a propeller blade. If the original design had corrosion protection and the propeller manufacturer’s ICAW call for corrosion protection, then the corrosion protection should be maintained to those instructions. Therefore, do not return polished propeller blades to service without verification of acceptability.

http://rgl.faa.gov/Regulatory_and_Guidance_Library\rgSAIB.nsf/(LookupSAIBs)/NE-08-22?OpenDocument

Whether the Rolite "sealant" meets that definition, I don't know...

Trapper John
 
Trapper John said:
My memory is a little fuzzy, but what I remember is Sensenich was taking the position that polishing a prop was not good, because whatever protective coating that was on the prop would be removed, and that would cause accelerated corrosion. I don't think Sensenich was the only manufacturer taking this position, either.

Here's FAA's take on it:

Polished propeller blades are rarely an acceptable configuration. Corrosion protection such as paint and anodize should not be removed from the surface of a propeller blade. If the original design had corrosion protection and the propeller manufacturer’s ICAW call for corrosion protection, then the corrosion protection should be maintained to those instructions. Therefore, do not return polished propeller blades to service without verification of acceptability.

http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgSAIB.nsf/(LookupSAIBs)/NE-08-22?OpenDocument

Whether the Rolite "sealant" meets that definition, I don't know...

Trapper John
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Right -- I think was in response to highly polished props that no longer had the factory finish.
I don't know if Rolite is a stripper -- in that case, it would be cheaper to use neverdull...
 
Is that referring to polished chrome? There is a problem with decorative chrome plating in that it can accelerate corrosion of the steel underneath and not be easily detected if improperly applied. Prop shops I have dealt with will not return a chromed propeller to airworthiness.

Chapter 6 of AC 43.13-1B deals with corrosion and mentions in paragraph 31:

in platings that corrode before steel, such as zinc or cadmium, slight breaks or cracks throughout the plating will not result in rusting of the exposed steel. With the surface metal corroded, the steel is protected. However,​
when the steel corrodes faster than the plate metal, such as chromium, the amount of protection depends on the tightness of the plating​
​

Trapper John said:
My memory is a little fuzzy, but what I remember is Sensenich was taking the position that polishing a prop was not good, because whatever protective coating that was on the prop would be removed, and that would cause accelerated corrosion. I don't think Sensenich was the only manufacturer taking this position, either.

Here's FAA's take on it:

Polished propeller blades are rarely an acceptable configuration. Corrosion protection such as paint and anodize should not be removed from the surface of a propeller blade. If the original design had corrosion protection and the propeller manufacturer’s ICAW call for corrosion protection, then the corrosion protection should be maintained to those instructions. Therefore, do not return polished propeller blades to service without verification of acceptability.

http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgSAIB.nsf/(LookupSAIBs)/NE-08-22?OpenDocument

Whether the Rolite "sealant" meets that definition, I don't know...

Trapper John
Click to expand...
 
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Props can be polished, there is no rule to stop you from doing it.

when you do. to keep it bright use "Evershield" from the Stewart brothers web site

http://www.stewartsystems.aero/product/9c5fda3d-971a-4e9c-bcaa-40f1a448795c.aspx

you will never need to polish it again.

The prop manufactures must build the prop IAW the production certificate, and the repair shops must repair it IAW the manufacturers manuals, both must replace any protective coating called for in the manual.

in the field we are not prohibited from removing the paint and anodized coating, and polishing the front side of the prop.simply because we are not bound to the overhaul manual. only the ICAs for the prop. which for the Sensenich is the owners manual.
 
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Steve said:
Is that referring to polished chrome? There is a problem with decorative chrome plating in that it can accelerate corrosion of the steel underneath and not be easily detected if improperly applied. Prop shops I have dealt with will not return a chromed propeller to airworthiness.
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A couple points.

Props that were not manufactured as a chrome prop can not be chromed in the field, Props can only be worked on by certified prop shops and they are bound to over haul the prop IAW the manufacturers overhaul manual.

McCauley does make a chromed prop. but that prop still can not be re-chromed in the field, only at a certified prop shop.

The A&P in the field may only do minor repairs on props, blending and polishing is a minor repair.

see 43.Appendix A
 
Tom-D said:
A couple points.

Props that were not manufactured as a chrome prop can not be chromed in the field, Props can only be worked on by certified prop shops and they are bound to over haul the prop IAW the manufacturers overhaul manual.

McCauley does make a chromed prop. but that prop still can not be re-chromed in the field, only at a certified prop shop.

The A&P in the field may only do minor repairs on props, blending and polishing is a minor repair.

see 43.Appendix A
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Tom...

"Chromed" implies an additional surface treatment. I don't want to do that. I want to remove the accumulated grime mixed into what appears to be a superficial surface protection (underneath is anodized aluminum).

It has the consistency and adhesion of very old wax.

I'd like to strip that without removing the underlying treatment, then re-coat with whatever protecting film is appropriate.

Will this product do that?
 
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dmccormack said:
Tom...

"Chromed" implies an additional surface treatment. I don't want to do that. I want to remove the accumulated grime mixed into what appears to be a superficial surface protection (underneath is anodized aluminum).

It has the consistency and adhesion of very old wax.

I'd like to strip that without removing the underlying treatment, then re-coat with whatever protecting film is appropriate.

Will this product do that?
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Anodizing is really a coating of corrosion applied by controlled electrochemical means. So, whatever you use to clean your anodized surface needs to not mechanically or chemically remove the anodizing film. I'd try a neutral-pH cleaner with a "non-scratch" grade of scotch-brite pad first.


Trapper John
 
Trapper John said:
Anodizing is really a coating of corrosion applied by controlled electrochemical means. So, whatever you use to clean your anodized surface needs to not mechanically or chemically remove the anodizing film. I'd try a neutral-pH cleaner with a "non-scratch" grade of scotch-brite pad first.


Trapper John
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That I can do... and I think the addition of some abrasion (scotch brite pad) will likely remove the gummy reside.

I used Simple green for Aircraft on the underside and the cowling with no ill effect (it looks great, actually!)

I'll use that as a cleaner in concert with the pad.

Thanks for the advice!!
 
Tom-D said:
Props can be polished, there is no rule to stop you from doing it.

..................................

The prop manufactures must build the prop IAW the production certificate, and the repair shops must repair it IAW the manufacturers manuals, both must replace any protective coating called for in the manual.

in the field we are not prohibited from removing the paint and anodized coating, and polishing the front side of the prop.simply because we are not bound to the overhaul manual. only the ICAs for the prop. which for the Sensenich is the owners manual.
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I would like to see the reference you are using that you claim "simply because we are not bound to the overhaul manual". If a mechanic is going to alter a product (propeller) from the TCDS then he needs approved data to do this.

As a mechanic you are bound to the maintenance instructions provided for the product at time of manufacture. If the manufacturer didn't provide a MM, OM or similar document then you could refer to AC43 for guidance.

http://www.faa.gov/about/office_org...tions/data/interps/2010/Inter AC 43-13-1B.pdf

As a mechanic making a required signoff in maintenance records (which you must do in the instance of polishing the prop) you should reference your data you are using to accomplish this.
 
Tom-D said:
The A&P in the field may only do minor repairs on props, blending and polishing is a minor repair.

see 43.Appendix A
Click to expand...

It's a "repair" if you are filing, then blending and polishing the affected area. If a mechanic is polishing the entire prop it now becomes an alteration. (see FAR 1)
 
dmccormack said:
Tom...

"Chromed" implies an additional surface treatment. I don't want to do that. I want to remove the accumulated grime mixed into what appears to be a superficial surface protection (underneath is anodized aluminum).

It has the consistency and adhesion of very old wax.

I'd like to strip that without removing the underlying treatment, then re-coat with whatever protecting film is appropriate.

Will this product do that?
Click to expand...
You do not have a Chromed prop. don't worry about that.

The blades are anodized at the factory, it is a light gray coating that can not be stripped chemically. It is a corrosion preventive for aluminum. do not worry about it coming off, it must be ground off if you wish to polish.

Remove the prop, strip it both sides and repaint the back side with one coat of flat black.
 
Rotor&Wing said:
It's a "repair" if you are filing, then blending and polishing the affected area. If a mechanic is polishing the entire prop it now becomes an alteration. (see FAR 1)
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Not true. If the protective coating is required to be there, the prop would require a prop shop to replace the alodizing every time you got a rock chip,

We've been thru this with the FSDO and Sensenich agrees.

Major repairs and alterations are listed in FAR 43-Appendix A

(3) Propeller major alterations. The following alterations of a propeller when not authorized in the propeller specifications issued by the FAA are propeller major alterations:

(i) Changes in blade design.

(ii) Changes in hub design.

(iii) Changes in the governor or control design.

(iv) Installation of a propeller governor or feathering system.

(v) Installation of propeller de-icing system.

(vi) Installation of parts not approved for the propeller.

Paint and protective coatings are not there.
 
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Rotor&Wing said:
It's a "repair" if you are filing, then blending and polishing the affected area. If a mechanic is polishing the entire prop it now becomes an alteration. (see FAR 1)
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ANY Repair must be logged, major minor does not matter, it must be returned to service with an entry in the maintenance records.

minor repairs to a prop are all any A&P-IA can do in the field.

65.81 General privileges and limitations.

(a) A certificated mechanic may perform or supervise the maintenance, preventive maintenance or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments), and may perform additional duties in accordance with §§65.85, 65.87, and 65.95. However, he may not supervise the maintenance, preventive maintenance, or alteration of, or approve and return to service, any aircraft or appliance, or part thereof, for which he is rated unless he has satisfactorily performed the work concerned at an earlier date. If he has not so performed that work at an earlier date, he may show his ability to do it by performing it to the satisfaction of the Administrator or under the direct supervision of a certificated and appropriately rated mechanic, or a certificated repairman, who has had previous experience in the specific operation concerned.

(b) A certificated mechanic may not exercise the privileges of his certificate and rating unless he understands the current instructions of the manufacturer, and the maintenance manuals, for the specific operation concerned.

[Doc. No. 1179, 27 FR 7973, Aug. 10, 1962, as amended by Amdt. 65–2, 29 FR 5451, Apr. 23, 1964; Amdt. 65–26, 45 FR 46737, July 10, 1980]
 
Rotor&Wing said:
I would like to see the reference you are using that you claim "simply because we are not bound to the overhaul manual". If a mechanic is going to alter a product (propeller) from the TCDS then he needs approved data to do this.

As a mechanic you are bound to the maintenance instructions provided for the product at time of manufacture. If the manufacturer didn't provide a MM, OM or similar document then you could refer to AC43 for guidance.

http://www.faa.gov/about/office_org...tions/data/interps/2010/Inter AC 43-13-1B.pdf

As a mechanic making a required signoff in maintenance records (which you must do in the instance of polishing the prop) you should reference your data you are using to accomplish this.
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You must be unaware of what the ICAs say on the minor repair of the prop. because that is all we have to go by in the field. because that is what the manufacturers allow us to do, and blending and polishing is what is given as a repair in the field by any A&P doing a minor repair.

You as an A&P-IA can not comply with the overhaul manual, simply because the routines there are a major repair.
 
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dmccormack said:
That I can do... and I think the addition of some abrasion (scotch brite pad) will likely remove the gummy reside.

I used Simple green for Aircraft on the underside and the cowling with no ill effect (it looks great, actually!)

I'll use that as a cleaner in concert with the pad.

Thanks for the advice!!
Click to expand...

DO NOT touch that prop with any thing abrasive. NOTHING If you wouldn't wipe you butt with it, don't use it on the prop.

Yes chemical cleaners and soft bristle brushes are OK.
 
Tom-D said:
You must be unaware of what the ICAs say on the minor repair of the prop. because that is all we have to go by in the field. because that is what the manufacturers allow us to do, and blending and polishing is what is given as a repair in the field by any A&P doing a minor repair.

You as an A&P-IA can not comply with the overhaul manual, simply because the routines there are a major repair.
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You do have some very "amusing" interpretations.

Tom-D said:
Props can be polished, there is no rule to stop you from doing it.



The prop manufactures must build the prop IAW the production certificate, and the repair shops must repair it IAW the manufacturers manuals, both must replace any protective coating called for in the manual.

in the field we are not prohibited from removing the paint and anodized coating, and polishing the front side of the prop.simply because we are not bound to the overhaul manual. only the ICAs for the prop. which for the Sensenich is the owners manual.
Click to expand...


Back to the original topic, please site for me where you can "alter" a prop by polishing it (remove the protective coating). No bloviating, just data please.
 
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Tom-D said:
ANY Repair must be logged, major minor does not matter, it must be returned to service with an entry in the maintenance records.

minor repairs to a prop are all any A&P-IA can do in the field.

65.81 General privileges and limitations.

(a) A certificated mechanic may perform or supervise the maintenance, preventive maintenance or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments), and may perform additional duties in accordance with §§65.85, 65.87, and 65.95. However, he may not supervise the maintenance, preventive maintenance, or alteration of, or approve and return to service, any aircraft or appliance, or part thereof, for which he is rated unless he has satisfactorily performed the work concerned at an earlier date. If he has not so performed that work at an earlier date, he may show his ability to do it by performing it to the satisfaction of the Administrator or under the direct supervision of a certificated and appropriately rated mechanic, or a certificated repairman, who has had previous experience in the specific operation concerned.

(b) A certificated mechanic may not exercise the privileges of his certificate and rating unless he understands the current instructions of the manufacturer, and the maintenance manuals, for the specific operation concerned.

[Doc. No. 1179, 27 FR 7973, Aug. 10, 1962, as amended by Amdt. 65–2, 29 FR 5451, Apr. 23, 1964; Amdt. 65–26, 45 FR 46737, July 10, 1980]
Click to expand...

Removing the protective coating and polishing the entire prop is an alteration.
 
Here's my plan -- I will clean off the obvious grimy residue using Simple green for Aircraft and a lightweight dish scrubbing sponge (the shop towels I was using were leaving more residue than removing).

I don't plan on taking any of the surface protection off (I can't unless I sand it off).

Also, while we're on the topic -- is repainting the tips considered normal preventative maintenance?
 
Tom-D said:
DO NOT touch that prop with any thing abrasive. NOTHING If you wouldn't wipe you butt with it, don't use it on the prop.

Yes chemical cleaners and soft bristle brushes are OK.
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Acids will indeed remove anodizing, so it's important to know what's in the chemical cleaner you use.


Trapper John
 
Trapper John said:
Acids will indeed remove anodizing, so it's important to know what's in the chemical cleaner you use.


Trapper John
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Any acid he will use won't. I strip and refinish props when needed. I do this by using a good quality epoxy stripper, and it does not remove the hydroxide coating we refer to as the alodizing.
 
dmccormack said:
Here's my plan -- I will clean off the obvious grimy residue using Simple green for Aircraft and a lightweight dish scrubbing sponge (the shop towels I was using were leaving more residue than removing).

I don't plan on taking any of the surface protection off (I can't unless I sand it off).

Also, while we're on the topic -- is repainting the tips considered normal preventative maintenance?
Click to expand...

It should work.
 
Rotor&Wing said:
Please provide the documentation to this.
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Read the Sensenich web page forums, Denny Pollard is a FAA airworthiness inspector, he could not show any requirements to not remove the paint and anodizeing and polish the prop.

It is a minor alteration IAW Sensenich and requires no special paper work or approval. minor alterations/repairs never do.

As far as approval in writing, there is none, because it is the same approval as you need to strip and polish an aircraft that came with paint.

The FAA couldn't show me any requirements to not polish the prop whil in service, I'll wager you can either. Quote 1 set of ICAs that forbid it.
 
Tom-D said:
Any acid he will use won't. I strip and refinish props when needed. I do this by using a good quality epoxy stripper, and it does not remove the hydroxide coating we refer to as the alodizing.
Click to expand...

Alodizing and anodizing are two very different processes.


Trapper John
 
Trapper John said:
Alodizing and anodizing are two very different processes.


Trapper John
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Yes very much so....... Anodizing is an electro/chemical process that produces a hydroxide film on aluminum.

Alodine, is a 6 % solution of chromic acid with neutrail PH factor that produces an artificial hydroxide film on the surfats of aluminum , that looks very much like a coffee stain.

I hope I did not mislead anyone by saying one is the same as the other.

You can use Alodine in the field, you can not do the ANodizing with out special equipment.That is why all process in the propeller manufactures overhaul manual are considered major repairs,

that is why "we" as A&Ps can not use the overhaul manual as approved data to return to service, because we are not allowed to make major repairs to propellers.

And / OBTW owner maintenance as per 43.A c. item, 9 says:



(9) Refinishing decorative coating of fuselage, balloon baskets, wings tail group surfaces (excluding balanced control surfaces), fairings, cowlings, landing gear, cabin, or cockpit interior when removal or disassemble of any primary structure or operating system is not required.


How does that effect a prop blade? can an owner strip and refinish a blade?
 
Tom-D said:
It is a minor alteration IAW Sensenich and requires no special paper work or approval. minor alterations/repairs never do.
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So your contention is for minor alterations and minor repairs an A&P is not required to use a source of acceptable or approved data?

Curious, how do you make the logbook entry for polishing a propeller?

43.13 Performance rules (general).

(a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in §43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.
(b) Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).
 
This is from AC 20-37e:

205. LIMITATIONS. Operational and service personnel should be familiar with the following limitations during any inspection.

e. Blade Polishing. The FAA receives frequent inquiries from airplane owners and maintenance personnel asking whether it is acceptable to polish propeller blades. It is almost always not acceptable. Corrosion protection such as paint and anodize should not be removed from the surface of a propeller blade. Propeller blades must be maintained to the type design. If the original design had corrosion protection and the instructions for continued airworthiness call for corrosion protection, then the corrosion protection should be maintained to those instructions.

206. PROCEDURES FOR MAINTENANCE.
b. Operators Cannot Do the Following:

(8) Do not polish blades unless specifically permitted by the manufacturer’s instructions.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/895eff1883ee06768625707b00727fd6/$FILE/AC%2020-37e.pdf
 
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dmccormack said:
I read that article last week and it was interesting, but did not address removal of superficial grime/dirt/marks.

"Polishing" to the point of removing the factory surface is not cleaning.
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Just curious, have you asked a prop shop how much to refinish the prop? Last fixed pitch one I had done was very inexpensive.
 
Rotor&Wing said:
So when you do an engine overhaul, what do you use as approved data?
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Props and engines are treated different, the A&P can use the engine manufacturers overhaul manual because the engine overhauls are not major repairs, a prop overhaul is a major repair.

and the disassemble, repair of any prop is a major repair.

the authorized data to use by an A&P is the Instructions for Continued Airworthiness, written by the prop manufacturer and approved by the FAA.

you as an A&P use the propeller manufacturer's overhaul manual as a return to service data, you just put your self in violation of FAR 65.81, and have given the FAA the proof you exceeded your privileges and limitations.as an A&P
 
dmccormack said:
I read that article last week and it was interesting, but did not address removal of superficial grime/dirt/marks.

"Polishing" to the point of removing the factory surface is not cleaning.
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who ever wrote that article is wrong IAW the airworthiness section of the FAA.

Simply because there is no limit to how much a prop blade can be blended as long as it remains with in blade profile.

If the prop can not be blended and returned to service with a minor repair such as blending and polishing it would require the prop shop to overhaul it each and every time it had a stone hit.

WE have no requirement in the field to replace the Anodizing in the field and no limit as to how much can be removed in the ICAs
 
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