Leaking grease on windscreen... is this normal?

So here I am with 10.7 hours on my brand new 9A with a hartzell CS prop, and I'm seeing a fine mist of grease showing up on my windscreen. At about hour 6, I had a rather large deposit show up which caused me to pull the spinner. I discovered that about a tablespoon of grease was deposited on the inside of the spinner directly opposite one of the grease zirks on the hub, which coincidentally no longer had the little plastic cover snapped closed. I snapped the cover back on cleaned up the spinner. Today on a lap around Austin, I again had another fine mist of grease show up on the windscreen. This time the inspection revealed a smaller amount of grease ( about a teaspoon ) on opposite sides of the spinner, again directly above two grease zirks which no longer had the caps snapped closed.

?????

The grease zirk caps are token at best. They are made of very light weight plastic ( friction fit ), and could not possibly be permanent. What's going on here?

I understand that CS props that have been overhauled ( which this has ) can sometimes leak a small amount of grease, but this is too coincidental to be over greasing.... or is it?

Are these little plastic caps the only thing that keeps small amounts of grease from escaping? If so, why aren't they made of stronger stuff or at least have a better locking mechanizm.

Many thanks for any wisdom you can provide.

- Jim

Safety wire the caps on.

I had the same problem along time ago. The problem I had was a bad grease zirk along with one rubber cap that had slung off. I installed new buna rubber, (not plastic) grease zirk caps and used very small safety wire around the caps to prevent them from coming off the grease zirk. This was done last year and I've had no problems since.

Bad Zirk for sure, they are standard size and you can pick them up at the auto store. The caps are just dust covers, I pulled mine off and threw them away they don't stay on anyway. You could actually just put plugs in the TE fittings as you lube from the LE and watch it come out the TE. Probably should relube now that you have slung that much grease out.

Jim,

I used to get a little pile of grease inside the spinner also. Mine came from poorly (Hartzell factory) placed rtv between the hub mating surfaces. Another thing to check are the four "corner" bolts, which clamp around the prop roots, and go through the spinner back plate. Many have found those to be needing proper torquing shortly after initial flights. I seem to recall that the zerks have little ball valves in them, and that the blue covers are not really doing much anyway (I might be wrong on this - clean one off and look for the little shiny ball in the zerk). It sounds like you are not see streaks coming out from the blade roots?

Jim, I would encourage you to check all those things, but be advised that my brand-new Hartzell prop squirted a bit of grease from the blade hubs during its "break-in". In took no-kidding 50 hours or so before it stopped squirting out little bits of grease. I think its more-or-less normal for new (and probably for overhauled) C/S props. (if you're getting grease from elsewhere, then that might not be normal...)

Just as another data point, it took my prop about 3 or 4 hours to stop spitting. This was when it was brand new, and also around 500 hours or so when I had it resealed. When it started spitting again before the reseal, it started all at once when the little thin sheet of rtv they use to seal the halves together extruded its way out and was in the little pile of grease on the spinner.

I'm awaiting my new Hartzell which is coming in 3 weeks. I hope it doesn't leak! On my Maule after a Hartzell overhauled it began to spit grease in very small amounts, speckles on the windshield, after about 100 hrs. My mechanic loved to "top off" the grease at every annual. Pumping it in one fitting until it oozed out the hole where another was removed. I visited a local Harzell approved shop who were anxious to reseal it for me at half the price of the overhaul but at the same time said they do not need to be greased like this. I stopped the regreasing at the annuals, continued to fly it, the "speckling" of grease dropplets ended and it has worked flawlessly with now 600 hours on it. by the way, it was a new hub, replaced at the overhaul too. No, all the grease did not leak out! We are talking about very small quantities streaking out from the hub and eventually getting thrown back so you could see them when flying into the sun. No accumulation inside the spinner. I think the prop may have been overgreased, or the problem solved itself with use.

MT does it also....

JordanGrant said:

Jim, I would encourage you to check all those things, but be advised that my brand-new Hartzell prop squirted a bit of grease from the blade hubs during its "break-in". In took no-kidding 50 hours or so before it stopped squirting out little bits of grease. I think its more-or-less normal for new (and probably for overhauled) C/S props. (if you're getting grease from elsewhere, then that might not be normal...)

Click to expand...

I am getting it with the MT also. The unit was OH'd recently and the fine streaks showed up on the wind screen, I thought the front PSRU seal was leaking but it is not. It is surplus grease from the hub and should all be gone soon. There are no zurks with the MT, it is more or less a sealed unit.

tomagin said:

I'm awaiting my new Hartzell which is coming in 3 weeks. I hope it doesn't leak! On my Maule after a Hartzell overhauled it began to spit grease in very small amounts, speckles on the windshield, after about 100 hrs. My mechanic loved to "top off" the grease at every annual. Pumping it in one fitting until it oozed out the hole where another was removed. I visited a local Harzell approved shop who were anxious to reseal it for me at half the price of the overhaul but at the same time said they do not need to be greased like this. I stopped the regreasing at the annuals, continued to fly it, the "speckling" of grease dropplets ended and it has worked flawlessly with now 600 hours on it. by the way, it was a new hub, replaced at the overhaul too. No, all the grease did not leak out! We are talking about very small quantities streaking out from the hub and eventually getting thrown back so you could see them when flying into the sun. No accumulation inside the spinner. I think the prop may have been overgreased, or the problem solved itself with use.

Click to expand...

The prop shop here in Minneapolis said the same thing. Maybe a pump or two every year or two, but not if it doesn't leak. I don't grease mine unless the grease comes out.

David,

That is, in a way, good news insofar that your PSRU is not leaking Mine is due soon, and I was concerned at your experience with the PSRU......from new, I have seen no apparent leaks from my MT.

AllanC

My Hartzel did this...

My Hartzel on my Rocket did the same thing, fine mist on the windscreen. I asked a local A&P and he said the prop was shot, needed seals, bearing, $$$$...YIKES! My prop had less than 300 hours on it and I thought this could not be right so called Hartzel and asked them. The conversation went like this:

ME: 'My prop is misting on my windscreen...'
HARTZEL: 'Did you recently service the prop?'
ME: 'Yes, I just did the yearly condition inspection (annual) and greased the prop IAW the manual...'
HARTZEL: 'Next time, don't do that'
ME: '???????OK??????'

Long story short, Hartzel told me if the prop is working properly and not leaking prior DON'T FILL IT WITH GREASE. Sure enough, after a few more flights it quit misting and has continued to work great until recently replaced by a new MT by the new owner.

Putting a new BA Hartzel on my Fastback -4 and WON'T GREASE IT!

ood luck with yours!

Just for posterity:
The Hartzell manual tells you to grease the hub at annual (or, IIRC, every 100 hours). The procedure is to remove one zerk on each side and pump a specified number of pumps into each side - I think it was 6 pumps each - OR STOP if grease begins to come out of the other hole (where you removed the zerk).
As far as my data point goes, I've followed that procedure for the 2 annuals I've done and I've not had grease come out since the initial break-in. I'm a very satisfied Hartzell customer.

Problem solved, thanks for all the good tips.

It was the zerks.

I did try the local auto parts store for replacements, only to find that the fine machine threads on the Hartzell zerks were no where to be found. As it turns out your garden variety automotive grease zerk has a course thread and it about half the length of a prop zerk.

I gave a call to Jordon Prop in San Antonio. Since these were the folks that overhauled the prop in the first place, I though they might be a good source of info. They comped me a free set of zerks, which arrived on my door step the next day. I installed them this afternoon and went on a test flight. I'm thankful to say the days of my greasy windscreen are at an end.

My guess is that having the prop sit on the shelf for 18 months after an overhaul was part of the problem. The important thing to remember is that they can go bad. Rather it was just a bad batch to start with or short shelf life, if your leaking out the zerks, replacem

- Jim

The hub comes from Hartzel packed with Aero 6 grease. You have to stay with what's in there. No mixing. When you have it O/H'd ask about going with Aero 5. Less chance of spitting. They don't pack at the factory with 5 because then the prop has a low temp limit.... Like really cold. Probably don't want to run your motor that cold anyway.

5 holds the oil in the grease better than 6, or 22 for that matter. Unless you are flying in the northern plains states in the middle of winter or Fairbanks the prop shop will probably agree with Aero 5.

SIX PUMPS

Jetj01 said:

....

Long story short, Hartzel told me if the prop is working properly and not leaking prior DON'T FILL IT WITH GREASE. Sure enough, after a few more flights it quit misting and has continued to work great until recently replaced by a new MT by the new owner.

Putting a new BA Hartzel on my Fastback -4 and WON'T GREASE IT!

ood luck with yours!

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For what it's worth, logic says that sooner or later the prop is going to need grease. So, I called Hartzell yesterday to check about the need and frequency to grease the prop hub. The Hartzell Tech said that for low time users (100 hours a year) like me, I should grease the hub only once per year. He said follow the steps in the book, but be sure:

1. Before adding grease check for any dried grease blobs that might clog the exit port on the zirc fittings. He suggested using a piece of safety wire through the fitting and if a dried clot of grease is there just poke it out of the way. It doesn't have to be removed just pushed aside so any excess grease can exit at the fitting.
2. When adding grease, only add six pumps on the grease gun. No more. He said the biggest problem they experience is "over servicing". He said people think they need to keep pumping until they see grease come out of the opposite fitting. He's had people call who've put a whole tube of grease in the hub because they didn't see anything exiting out the opposite side, and then experienced problems with grease leaking through the seals. All that grease has to go somewhere and it will find a way to exit. So SIX PUMPS and no more.

Chris

JordanGrant said:

Just for posterity:
The Hartzell manual tells you to grease the hub at annual (or, IIRC, every 100 hours). The procedure is to remove one zerk on each side and pump a specified number of pumps into each side - I think it was 6 pumps each - OR STOP if grease begins to come out of the other hole (where you removed the zerk).
As far as my data point goes, I've followed that procedure for the 2 annuals I've done and I've not had grease come out since the initial break-in. I'm a very satisfied Hartzell customer.

Click to expand...

Just a few words of caution. remove all the zerks before adding grease. When the grease starts coming out of the hole reinsert the zerts. It is possible to destroy the prop seals if you leave in the other zerts while adding grease and get it to full.

Pat