Hartzell -- Grease "Seepage"

[bjdecker]

It seems that a large # of Hartzell CS propellers will tend to sling grease (rather, the oil from the grease). There's been some speculation as to the causes (Aeroshell 6 vs 5 grease), and mitigating some factors suggested -- store propeller horizontally, replace the seals after 2 years, change to Aeroshell 5, change to NYCO GN3058.

Since the changeover in January 2020, has anyone with the NYCO GN3058 grease experienced similar seepage?

Cheers!

 

[Mikeyb]

My prop was built late 2020 and delivered with the GN3058 grease. No evidence of any leakage in 3 years of operation and 120 hours of 30 minute flights

 

[Kyle Boatright]

It seems that a large # of Hartzell CS propellers will tend to sling grease (rather, the oil from the grease). There's been some speculation as to the causes (Aeroshell 6 vs 5 grease), and mitigating some factors suggested -- store propeller horizontally, replace the seals after 2 years, change to Aeroshell 5, change to NYCO GN3058.

Since the changeover in January 2020, has anyone with the NYCO GN3058 grease experienced similar seepage?

Cheers!

Tangentially related. My Hartzell, which came with Aeroshell 5, sat for 3 years before first flight. It misted oil on and off for the first year or so, and after that (and regreasing), the issue has resolved itself. I assume the initial leakage was because the grease separated and slung out the oil... Which is kind of what you implied. Anyway, my experience is that a little initial oil misting may resolve itself... What the NYCO does... Dunno.

 

[bjdecker]

Tangentially related. My Hartzell, which came with Aeroshell 5, sat for 3 years before first flight. It misted oil on and off for the first year or so, and after that (and regreasing), the issue has resolved itself. I assume the initial leakage was because the grease separated and slung out the oil... Which is kind of what you implied. Anyway, my experience is that a little initial oil misting may resolve itself... What the NYCO does... Dunno.

Thanks Kyle,

Back in 2019, about 4 years after I had ordered my propeller and 50 hours since it first ran, I noticed the mist on the windscreen. At that time, I sent my prop in for resealing/regreasing. $800 later it was all good. After another 100 hours or so, and then waiting 6 months for the paint shop to finish their work, the mist returned. I "purged" the Aeroshell 6 (yeah yeah, I know, you can't purge the grease from the hub because the propeller will explode...[eyeroll]) and put in Aeroshell 5 -- enough pumps to see the grease coming out of the hole had changed color. 3+ years, and 300 hours later, all still good.

So, yeah - I think the Aeroshell 6 grease tends to separate over time, then spews the oil down the blades and everywhere else. Aeroshell 5 doesn't seem to separate, but I haven't let the plane sit idle for very long either....dunno...

 

[Avanza]

It seems that a large # of Hartzell CS propellers will tend to sling grease (rather, the oil from the grease). There's been some speculation as to the causes (Aeroshell 6 vs 5 grease), and mitigating some factors suggested -- store propeller horizontally, replace the seals after 2 years, change to Aeroshell 5, change to NYCO GN3058.

Since the changeover in January 2020, has anyone with the NYCO GN3058 grease experienced similar seepage?

Cheers!

Generally speaking, not propeller related, a ball bearing should not be filled to more than 30 % with grease.
This is because the grease expands and may cause overheating of the bearing or protrude outside of the bearing house.
It would be interesting to know how the Hartzell overhaul instructions are written.

Good Luck

 

[Webb]

My 7A had a 2 blade metal MT prop that started slinging ~ 50 hours. Prop pulled and sent in to be checked. I was told it was over greased.
After return to service, it never slung again.

Has anybody ever heard of this?

 

[fl-mike]

Generally speaking, not propeller related, a ball bearing should not be filled to more than 30 % with grease.
This is because the grease expands and may cause overheating of the bearing or protrude outside of the bearing house.
It would be interesting to know how the Hartzell overhaul instructions are written.

Good Luck

These are not being used in a continuous rotary application. They move maybe ten degrees or less at any given time with a very low duty cycle.
Why they use a ball bearing in this application is odd to me. Seems like a thrust bearing or taper bearing would be better suited if using a bearing at all.

 

[Carlos151]

My Hartzell prop originally came with Aeroshell grease. A couple of years ago had it overhauled at the 6+ year mark. No issues found. Grease was replaced with the new Nyco grease per their new standards. Just doing the condition inspection for the second time since the changeover. My personal observation is that the Nyco grease does not separate like the Aeroshell grease does. It also does not seem to harden at all. It's definitely a different type of grease without the waxy residue and the separation of components. Availability is much better now compared to when the changeover happened and Nyco grease might as well have been called unobtamium grease.

 

[mfleming]

Mine had the NYCO GN3058 grease from the factory and started slinging grease bad enough that it was resealed at 80 hours. Now it’s starting to sling grease again at 180 hours. Really a bummer…

 

[jcarne]

Mine had the NYCO GN3058 grease from the factory and started slinging grease bad enough that it was resealed at 80 hours. Now it’s starting to sling grease again at 180 hours. Really a bummer…

Well that's not what a guy wants to hear from a factory new one.

 

[jcarne]

Switched to Aeroshell 5, no grease slinging in 400 hrs.

 

[BillL]

Mine had the NYCO GN3058 grease from the factory and started slinging grease bad enough that it was resealed at 80 hours. Now it’s starting to sling grease again at 180 hours. Really a bummer…

So just to quantify this grease slinging - - mine has spit grease on a long flight (saturated hot engine) since I installed it. Hartzell composite wide blade. I grease to spec each year. The slinging is really just a mist on the plexiglass and if not here I might not notice it.

As to why it separates, I was told by a career engineer in the lube industry that any grease with a clay base is the low cost formulation and will always separate. In a prop, in the grease gun on the shelf, . . . .anywhere, everywhere and can't prevent it. That said, I personally have no clue if this separation has anything to do with the grease spitting/slinging.

 

[Kyle Boatright]

As to why it separates, I was told by a career engineer in the lube industry that any grease with a clay base is the low cost formulation and will always separate. In a prop, in the grease gun on the shelf, . . . .anywhere, everywhere and can't prevent it.

I keep my grease gun (loaded with Aeroshell 5) in the freezer compartment in my beer fridge. I *think* that should slow or defer separation.

 

[bjdecker]

I keep my grease gun (loaded with Aeroshell 5) in the freezer compartment in my beer fridge. I *think* that should slow or defer separation.

Possibly, but it's not practical to keep the propeller+hub in the beer fridge

 

[pilotkms]

Had my Hartzell overhauled at the 6 year mark with 919 tach hours. They put the Nyco grease in it. 260 hours since OH and no slinging. And I grease it til it comes out clean from the exit hole.