Small oil spatter around nose cone

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johnm
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Small oil spatter around nose cone

Post by johnm »

This is a recent situation and not sure what the deal is. I have been told that simply cycling the prop will seat the gasket and it should stop but it has not. Any thoughts from and of you? DA 40 Hartzell composite constant speed prop.
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Chris B
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Re: Small oil spatter around nose cone

Post by Chris B »

With a Hartzell, the main issue is sufficient leakage that the hub starts to get dry. This will lead to buying a new hub, and possibly other exciting events! :(

But relatively rare small spatters should not be an issue. I've had this happen 2 or 3 times in the last ~800 hours, and my IA is not concerned unless it is persistent. Otherwise the prop should last as long as the engine.

The Hartzell hub should be greased *properly* every ~200 hours. But from speaking with two prop shops, screwing this up happens surprisingly often. Over-greasing (&/or not removing the appropriate fittings) is their biggest concern. This will blow the seals which then requires repair.

How many hours on your prop?

Chris
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Re: Small oil spatter around nose cone

Post by rwtucker »

Chris B wrote:The Hartzell hub should be greased *properly* every ~200 hours. But from speaking with two prop shops, screwing this up happens surprisingly often. Over-greasing (&/or not removing the appropriate fittings) is their biggest concern. This will blow the seals which then requires repair. Chris
What does the proper greasing involve Chris?
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Chris B
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Re: Small oil spatter around nose cone

Post by Chris B »

rwtucker wrote:What does the proper greasing involve Chris?
Hi Robert -

The process is described in the Hartzell manual:
  1. Remove all four zerk fittings
  2. Check the existing grease to make sure it is healthy (color & consistency). I use a Q-tip "dipstick."
  3. Reinstall the two correct zerk fittings (leading edge?)
  4. Ensure that the opposite fittings remain off
  5. Use only Aeroshell 5 or 6 grease
  6. Insert only small amounts (~6 pumps) on each side
  7. Reinstall the remaining two zerk fittings
All of these points are important, but adding too much grease is apparently the most common screw up. I have no personal experience, but reportedly the process for some other hubs is to pump grease through until it comes out fresh (similar to wheel bearings). But this is *very* bad with these Hartzell hubs.

Chris
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Re: Small oil spatter around nose cone

Post by smoss »

some points to note. Aeroshell 6 is the standard, but it separates a bit under high ambient temps (i.e. Las Vegas). You can change to Aeroshell 5 which the Hartzell manual says is more stable under high temps, but then you must eternally placard the airplane as "not for flight under -30F" or something (forgot the actual number, but it's pretty darn cold). I don't want to deal with the eternal placard, so I just deal with the mild separation. There is no oil per se in a Hartzell hub, but the grease separates into its oil and carrier components, and the fling you see on the blades and around the spinner, although technically the oil component, is actually grease.
This will become most evident on hot days when you cycle the prop back to high rpm after it's been run a while and hot already. I can depart from 115 F outside temp on max rpm with no grease fling, but if I were to say do a go-around at destination on high rpm, I get a pretty decent amount of grease flinging (it looks like a lot, but really it's pretty trivial). I learned all this while doing IFR training mid-summer in Vegas several years back and doing multiple approaches, etc. Now I rarely see it, but know when it will be there.
Another point is that the grease fittings actually leak the separated "oil" as well when it is hot, and it can accumulate inside the spinner right over the fittings and fling out from the spinner itself, instead of from the blade inserts-no significance at all.
The Hartzell manuals are on their website. The link for the aluminum blade one (mine) is:
http://hartzellprop.com/wp-content/uplo ... R21-WA.pdf
I'm sure the composite one is on there too.
Steve
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Chris B
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Re: Small oil spatter around nose cone

Post by Chris B »

smoss wrote:some points to note. <snip>
Great points, Steve.

FWIW, I switched to Aeroshell 5. The limitation is -40 (F or C). Presumably this is generally only relevant for guys flying in Class A, though parts of Canada - or Minnesota! - could apply. :D

Also, after looking at the Hartzell manual again, they recommend 100 hr or 1 year intervals (longer with frequent use). But based on the feedback from the prop shops and my IA that too much grease is a far more common issue, we have dialed that back to ~200 hrs.

Note that hubs for the similar vintage composite and aluminum Hartzell props are identical. So hub maintenance and durability is the same.

Chris
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Re: Small oil spatter around nose cone

Post by mdieter »

We had a grease splatter incident some time ago with the Hartzell. Small amount. Mechanic said it wasn't a problem. I haven't seen it since (fingers crossed). I guess it happens.
Mark
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Re: Small oil spatter around nose cone

Post by Lance Murray »

If your prop has some time on it a clean and reseal is not expensive and could ease your concerns. They will disassemble your prop, replace seals, inspect and re-grease it.
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