Hartzell Service Letter HC-SL-61-366

[M20F-1968]

I sent my prop out for its first overhaul since new.  It went out with Aeroshell 6 in it and was tagged for Aeroshell 6.  It came back with Aeroshell 5.  The shop blamed COVID and decreased staffing for the change.  Aeroshell 5 has a limitation for operations only > -40C.  Hartzell also has a Service Letter HC-SL-61-366 which recommends NYCO GN3058 Grease in all Hartzell propellers (with 3 exceptions, not including mine) once the prop is overhauled and purged of old grease.  See copy attached.  

Does anyone know why this change was made from Aeroshell 6?  What are the advantages of the new grease?  

In any case, Hartzell has recommended Aeroshell 6 and this new grease, not Aeroshell 5.  

Any thoughts on the matter?  The shop is willing to disassemble and purge the grease.  Should I use Aeroshell 6 or NYCO GN3058 Grease?  It seems that the correct answer is NYCO GN3058.

John Breda

[carusoam]

John,

There are discussions around here about the quirks of the two greases… one of them was technical like in availability… the other was related to keeping it from separating the oil from the thickener…. 
 

Also some discussion on flushing the prop hub one way or the other…

 

All that uninformative info aside…. Let me invite our prop guy to the conversation….  @Cody Stallings
 

Best regards,

-a-

[A64Pilot]

I would call Hartzell, they have excellent customer support.

 

[Shadrach]

4 hours ago, M20F-1968 said:

I sent my prop out for its first overhaul since new.  It went out with Aeroshell 6 in it and was tagged for Aeroshell 6.  It came back with Aeroshell 5.  The shop blamed COVID and decreased staffing for the change.  Aeroshell 5 has a limitation for operations only > -40C.  Hartzell also has a Service Letter HC-SL-61-366 which recommends NYCO GN3058 Grease in all Hartzell propellers (with 3 exceptions, not including mine) once the prop is overhauled and purged of old grease.  See copy attached.  

Does anyone know why this change was made from Aeroshell 6?  What are the advantages of the new grease?  

In any case, Hartzell has recommended Aeroshell 6 and this new grease, not Aeroshell 5.  

Any thoughts on the matter?  The shop is willing to disassemble and purge the grease.  Should I use Aeroshell 6 or NYCO GN3058 Grease?  It seems that the correct answer is NYCO GN3058.

John Breda

They did you a favor. The new formulation of Aeroshell 6 is shite. It separates quickly from the thickener and will often begin leaking past the seals in the first year of use. It’s a known problem and likely why your shop made the switch.

Edited August 22, 2021 by Shadrach

[MikeOH]

You want Aeroshell 5.  As Ross said, the shop did you a favor as the new Aeroshell 6 is crap.  I had my prop OHed and it leaked past the seals within a month.  Also, if you read the latest SL you are allowed to MIX the Aeroshell 5 in with Aeroshell 6.  No need to disassemble and purge out the #6. That's what I've been doing and the leaking has gone down.

I saw the NYCO option but know zip about its characteristics.  But, if it was me, I'd fly with the Aeroshell 5 and be happy.  I'm skeptical that our M20Fs are ever going to see -40, even at altitude.

[Cody Stallings]

Aeroshell #5 is a far Superior grease to #6.

I see propellers torn apart everyday that have been serviced with both, an it’s a nobrainer. 

When the new style #6 was introduced 3-4 yrs ago our shop had to warranty 14 propellers, most of which were 4 blade King Air props because this stuff was breaking down into oil so fast the Orings wouldn’t hold it back.

Jury is still out on the GN3058. It’s showing signs of being a good grease, just haven’t seen many props for maintenance yet that used it. 
 

letter from Hartzell below

Edited December 4 by Cody Stallings
Fat Fingers

[Ragsf15e]

39 minutes ago, MikeOH said:

You want Aeroshell 5.  As Ross said, the shop did you a favor as the new Aeroshell 6 is crap.  I had my prop OHed and it leaked past the seals within a month.  Also, if you read the latest SL you are allowed to MIX the Aeroshell 5 in with Aeroshell 6.  No need to disassemble and purge out the #6. That's what I've been doing and the leaking has gone down.

I saw the NYCO option but know zip about its characteristics.  But, if it was me, I'd fly with the Aeroshell 5 and be happy.  I'm skeptical that our M20Fs are ever going to see -40, even at altitude.

Yeah lots of higher flying airplanes (Sr22T) have a minimum temp around -40c and it’s pretty rare to get there even in the upper 20,000’s in the winter.  I’d be happy with the better grease.

[M20F-1968]

In the winter in New England at 18,000 feet i might see -40C.  What is the experience with the NYCO GN 3058.  This the experience with the Aeroshell 6 the reason for the change to the NYCO?  The way I read the service bulletin, all (except 3) Hartzell overhauled and new props after January 2020 should be using NYCO GN 3058.

John Breda

 

[N201MKTurbo]

No use for a C or F at -40.

[Mooney Dog]

23 minutes ago, N201MKTurbo said:

No use for a C or F at -40.

Thats got to be like, 233! 

[Hank]

11 hours ago, Mooney Dog said:

Thats got to be like, 233! 

Nah, I don't care for metric. Let's call it 420.

[N201MKTurbo]

32 minutes ago, Hank said:

Nah, I don't care for metric. Let's call it 420.

That's the beauty of -40, it doesn't matter what you like.

[Hank]

2 minutes ago, N201MKTurbo said:

That's the beauty of -40, it doesn't matter what you like.

That's true for ºC and ºF. But we were discussion Kelvin vs. Rankine, they only agree at 0. So -40 C/F = 233 K = 420 R.

[N201MKTurbo]

4 minutes ago, Hank said:

That's true for ºC and ºF. But we were discussion Kelvin vs. Rankine, they only agree at 0. So -40 C/F = 233 K = 420 R.

You are absolutely correct...

Berrrr

FWIW,

I ran a fridge once that got to 0.000006 Kelvin. I designed the control system for the sensor. It was a dilution fridge that cools by evaporating helium 3 into helium 4.

Edited August 23, 2021 by N201MKTurbo

[Mooney Dog]

On 8/23/2021 at 12:12 PM, N201MKTurbo said:

That's the beauty of -40, it doesn't matter what you like.

 

On 8/23/2021 at 12:16 PM, Hank said:

That's true for ºC and ºF. But we were discussion Kelvin vs. Rankine, they only agree at 0. So -40 C/F = 233 K = 420 R.

Either way you look at it, im gonna need another coat. 

[N201MKTurbo]

I wonder how cold the prop gets with an OAT of -40? It is connected to a hot crankshaft after all and has hot oil trying to get in.

[Shadrach]

34 minutes ago, N201MKTurbo said:

I wonder how cold the prop gets with an OAT of -40? It is connected to a hot crankshaft after all and has hot oil trying to get in.

It does not get hot at all unfortunately. I’ve pulled my prop in the winter after flight. The oil in the hub was cold. Might have been a bit warmer than ambient but not by much.

[Hank]

3 hours ago, Shadrach said:

It does not get hot at all unfortunately. I’ve pulled my prop in the winter after flight. The oil in the hub was cold. Might have been a bit warmer than ambient but not by much.

But that was after a low power descent, landing and taxi. Bet it was much warmer during cruise!

[Will.iam]

How much oil is circulating when the prop is not changing pitch? Maybe get more hot oil up in the hub when you vary the rpm’s back and forth a few times?

[carusoam]

5 hours ago, Mooney Dog said:

 

Either way you look at it, im gonna need another coat. 

In the -40 freezer…. People use Refigiwear….  https://www.refrigiwear.com/category/new-products?tf_source=google&tf_medium=ppc&tf_utm_campaign=Search+Brand&gclid=Cj0KCQjwsZKJBhC0ARIsAJ96n3XSit4-kEQ_M86WeGbQV06Feb-387GJabqS7r99R3fEmbij7EvFrIgaArMSEALw_wcB
 

Yes… that is a brand name for freezer wear….  

Best regards,

-a-

[Shadrach]

30 minutes ago, Will.iam said:

How much oil is circulating when the prop is not changing pitch? Maybe get more hot oil up in the hub when you vary the rpm’s back and forth a few times?

No oil is circulating. It’s a one way system. Excess oil spills from the system at the front crank bearing journal but what’s in the hub stays in the hub for the most part.

[Shadrach]

37 minutes ago, Hank said:

But that was after a low power descent, landing and taxi. Bet it was much warmer during cruise!

I’d take that bet. I don’t think it really warms up much at all.

[Ragsf15e]

20 hours ago, Shadrach said:

It does not get hot at all unfortunately. I’ve pulled my prop in the winter after flight. The oil in the hub was cold. Might have been a bit warmer than ambient but not by much.

Different airplane, similar but different system… I’ve seen prop ice when just below freezing air temps.  Formed about the same time as on the wings.  I suspect the 2500ish rpm prop cools itself pretty quickly to ambient temp even though the hub might be slightly warmer.

[Shadrach]

49 minutes ago, Ragsf15e said:

Different airplane, similar but different system… I’ve seen prop ice when just below freezing air temps.  Formed about the same time as on the wings.  I suspect the 2500ish rpm prop cools itself pretty quickly to ambient temp even though the hub might be slightly warmer.

Yeah, i suspect if the oil is going to warm at all (and I don’t think it does) it would happen on the way back to the barn.

[A64Pilot]

The prop hub will heat soak some because the crank is hot and it will conduct heat, but there is no oil flow. Often when you pull a prop you will find a lot of sludge in there because there is no flow, that’s why we cycle the prop three times during run up, we try to get some fresh oil in there.

However I’m sure Hartzell has taken into account any heat that may be conducted into the hub