Prop keeps slinging off paint

[aggiepilot04]

Howdy all,

Sensenich overhauled the Hartzell prop on my Mooney in August 2015, and it only had about 50 hours on it before I started losing paint the first time.  The airplane was down for repairs for a while though, so the paint had had over a year to cure.  I let Sensenich know what had happened, and they picked it up and repainted it for me at no charge (I still had to pay the local mechanic to pull the prop and reinstall).  However, less than 10 hours (30 days) after having it reinstalled, it happened again.  Images from each time are attached.  This last time, I ran through some light precip on the approach into AUS.  If the precip is what caused this, avoiding precip indefinitely isn't really realistic (is it??).  I wipe bugs from all leading edges (including the prop) after each flight, but I have only used water and a microfiber towel thus far since my paint job is somewhat fresh.  Sensenich says they haven't had this issue before and that precip shouldn't cause it.  They're going to take care of it again, but I'd really like for it to stop happening.  Anyone else had this issue or have any ideas what would cause it?  Thanks in advance.

[KSMooniac]

Poor prep work, or defective paint/primer.

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[aggiepilot04]

Just now, KSMooniac said:

Poor prep work, or defective paint/primer.

Sent from my LG-LS997 using Tapatalk
 

That would have been my guess the first time.  However, the second paint job was actually completed by a different Sensenich shop a year and a half later (PA was closer for the previous owner, GA is closer for me).  Plus, you would think that they would take every precaution to make sure that it was prepped properly on a do-over so that they didn't have to do the work for free again...

[KSMooniac]

You would think so, but most likely they have the same procedures at both shops, executed by someone making $15/hr and not giving a damn.

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[Yetti]

sherwin williams I think makes the prop paint

I would be pretty annoyed

I have pulled the prop twice and wire tied it twice on the second pull.   I got a "that wire job will pass, but we would not want people to know our shop do it, so I had to cut if off and do it again.

They make a 3/4" open end torque wrench.... who knew.

[takair]

First photo seems to show primer below and the second photo shows no primer.  Both may indicate poor prep work.  From my little knowledge of painting, there is an optimal point to add paint to primer...perhaps that was not managed well the first time.  The second photo makes me question if it was primed at all.  Do I see that correctly?

[N201MKTurbo]

Back before everything became toxic these things didn't happen.

I always used Tempo propeller paint. It never failed.

Sorry for your loss, of paint that is.

[aggiepilot04]

24 minutes ago, takair said:

First photo seems to show primer below and the second photo shows no primer.  Both may indicate poor prep work.  From my little knowledge of painting, there is an optimal point to add paint to primer...perhaps that was not managed well the first time.  The second photo makes me question if it was primed at all.  Do I see that correctly?

I actually have the pictures attached out of order.  The gold looking one is the most recent paint failure.  I am unfamiliar with the process of prep/priming/painting, but you're right...that's what it looks like.  Either that, or the primer didn't stick to the prop the first time, and the paint didn't stick to the primer the second.

[aggiepilot04]

14 minutes ago, N201MKTurbo said:

Back before everything became toxic these things didn't happen.

I always used Tempo propeller paint. It never failed.

Sorry for your loss, of paint that is.

Thanks for the input.  I will try to find out what kind of paint they used.

[DAVIDWH]

According to my AP, common prob with the newer grey paints.

Prop shop did my Hartzell Scimitar in black at overhaul.

No more worries mate.

[Andy95W]

When your mechanic installs your prop this time, have him also install Prop Guard.  FAA-PMA'ed.

http://www.mcfarlaneaviation.com/Products/?CategoryID=135&ID=6554170&

[RLCarter]

Two types of bonding (primer/paint), the best is a chemical bond where you prime and paint within the given time. If for what ever reason you can't get the paint on in time then it's a mechanical bond. Looks to me both photos was either the wrong paint for the primer or piss poor prep. I would tell them to completely strip and redo, also never wax or seal any new paint for a minimum of 120 days, sealing traps the solvents in the paint and you get what is called "solvent popping" (go figure) which looks like air bubbles that show up days/weeks later. 

[Aerodon]

26 minutes ago, Andy95W said:

When your mechanic installs your prop this time, have him also install Prop Guard.  FAA-PMA'ed.

http://www.mcfarlaneaviation.com/Products/?CategoryID=135&ID=6554170&

I have not had good experience with Prop guard - it fails in rain and ice.  And you would not want to complicate this repainting situation, something definitely not right.  Aerodon

[Hank]

Just now, Aerodon said:

I have not had good experience with Prop guard - it fails in rain and ice.  

Similar to what I've been told, too.

[smwash02]

I had my prop overhauled in Dallas and first light precip it shed the paint. Sent it back for a repaint and next light precip it shed the paint again. Looked just like your pictures.

I had the person who painted it years ago before the overhaul paint it and sent them the bill, which they surprisingly paid. Hasn't shed since and it's been through much worse. Good luck, it's certainly frustrating.

[carusoam]

Summary: That's an incredibly sensitive area...

1) leading edge of an airfoil

2) aluminum alloy surface

3) impact with rain and frozen bits

4) prep is going to be equally important

5) Byron mentioned a passivation process that was used on the gear... might apply here as well...

6) sand properly, wash, clean, passivate, first layer, second layer, stripes...

7) ask a lot of questions about the procedure including the time between each step...

8) Composite props haven't done any better.  Somebody with really good knowledge of the paint chemistry and what it takes to get it right needs to be involved...

Best regards,

-a-

[Andy95W]

1 hour ago, Aerodon said:

I have not had good experience with Prop guard - it fails in rain and ice.  And you would not want to complicate this repainting situation, something definitely not right.  Aerodon

Disagree.

Not been my experience at all. 3 airplanes, 4 propellers, and it has protected my props and stayed attached.  As far as rain and ice, it seems to not collect ice as readily as bare metal or paint.  

It must be applied correctly, and it will need to be re-done after about 6 years or 400 hours in my experience.  If flying through rain regularly, it would probably have to be replaced sooner.

[1964-M20E]

I repainted my prop myself and had similar results with the prop paint from Aircraft Spruce.

I stripped the prop, aloidine, zinc chromate and then the prop paint.

 

I may have rushed the process and I will try again at annual when I have more time.

[Godfather]

I would not be happy...

This is what almost 2k hrs looks like flying through all types of precipitation. 

[PTK]

14 hours ago, aggiepilot04 said:

That would have been my guess the first time.  However, the second paint job was actually completed by a different Sensenich shop a year and a half later (PA was closer for the previous owner, GA is closer for me).  Plus, you would think that they would take every precaution to make sure that it was prepped properly on a do-over so that they didn't have to do the work for free again...

You should have it done properly by someone who knows what they're doing and utilizing proper materials. 

Here's mine done by paint shop. No issues.

I wouldn't take it back to them. I'd take it to a paint shop and work it out for Sensenich to pay them directly or reimburse you. 

[jetdriven]

That paint is coming loose from the primer, they are exceeding the recoat window between primer and topcoat.   That and/or the primeris way too thick. IIRC its a wash primer, it should just barely be visible. its not acceptable, its shoddy work.

The only paint to put on a prop, is Sherwin Williams Polane. Its even called out for in the Type Certificate for many props.

Edited March 28, 2017 by jetdriven

[Andy95W]

For the PropGuard naysayers:

 4 years old, about 160 hours, including a couple of rain showers and one inadvertent icing encounter

(the grey paint is original, but the rest is gen-u-wine Rustoleum flat black and gloss white.)

[Cody Stallings]

On 3/27/2017 at 6:39 PM, aggiepilot04 said:

Howdy all,

Sensenich overhauled the Hartzell prop on my Mooney in August 2015, and it only had about 50 hours on it before I started losing paint the first time.  The airplane was down for repairs for a while though, so the paint had had over a year to cure.  I let Sensenich know what had happened, and they picked it up and repainted it for me at no charge (I still had to pay the local mechanic to pull the prop and reinstall).  However, less than 10 hours (30 days) after having it reinstalled, it happened again.  Images from each time are attached.  This last time, I ran through some light precip on the approach into AUS.  If the precip is what caused this, avoiding precip indefinitely isn't really realistic (is it??).  I wipe bugs from all leading edges (including the prop) after each flight, but I have only used water and a microfiber towel thus far since my paint job is somewhat fresh.  Sensenich says they haven't had this issue before and that precip shouldn't cause it.  They're going to take care of it again, but I'd really like for it to stop happening.  Anyone else had this issue or have any ideas what would cause it?  Thanks in advance.

Not enough V66 catalyst/Hardner.

Without enough it leaves the paint soft.

Sometimes shops will skimp on the proper amount of catalyst, in order to get the paint to dry faster, an avoid the Bake time.

BUT!!!! It always turns out just like this.

 

 

[carusoam]

Way to go Cody!

The go to guy for propellers!  

Best regards,

-a-

[JamesMooney]

Same problem here. The first hour after the prop was repainted, this is what it looked like....

Sounds like I need to get my prop re-painted. Not sure I trust the shop that did the work the first time (and they are the other side of the country).

Question: how much does it cost to have the prop repainted? And how long does it typically take? (How much downtime should I expect?)