Propeller Grease

[Geico266]

I decided to start my "rolling annual" since the RV-10 was down for a throttle c
able replacement and I had thethe cowl off. I decided to grease the Hartzel prop hub and grabbed the grease gun with Aero Shell #6 grease.

The grease seemed dry, like it had set up. It seemed to oump okay, but it got me to thinking how old was it. Does the grease have a self life? What is the proper procedure for greasing the constant speed hub?

[Walt]

From the Hatzell Standard Practices Manual:

B. Aluminum Hub Propellers
(1) Remove the lubrication fi tting caps from both sides of the hub assembly.
Remove the lubrication fi ttings from either the cylinder side, or engine side of
the hub assembly.
NOTE: It is preferable to apply grease to the fi tting located nearest the
leading edge of the blade on a tractor installation, or nearest the
trailing edge on a pusher installation. Greasing at this location
reduces the possibility of grease bypassing the bearing area and
entering the hub cavity.
(2) To prevent pressurization of the bearing cavity, use a piece of safety wire to
loosen any blockage or hardened grease at the threaded holes where the
lubrication fi ttings were removed.
(3) Lubricate the propeller in accordance with the appropriate instructions, below.
CAUTION: OVER LUBRICATING AN ALUMINUM HUB PROPELLER
MAY CAUSE THE GREASE TO ENTER THE HUB CAVITY,
LEADING TO EXCESSIVE VIBRATION AND/OR SLUGGISH
OPERATION. THE PROPELLER MUST THEN BE
DISASSEMBLED TO REMOVE THIS GREASE.
NOTE: If a pneumatic grease gun is used, extra care must be taken to avoid
excessive pressure buildup.
CAUTION: GREASE MUST BE APPLIED TO ALL BLADES OF A
PROPELLER ASSEMBLY AT THE TIME OF LUBRICATION.
1 Initial lubrication after assembly or overhaul: Using a hand operated
grease gun, apply approved grease to each lubrication fi tting until grease
emerges from the removed lubrication fi tting hole in a steady fl ow with no
air pockets.
CAUTION: GREASE MUST BE APPLIED TO ALL BLADES OF A
PROPELLER ASSEMBLY AT THE TIME OF LUBRICATION.
2 In-service lubrication: Using a hand operated grease gun, apply
approved grease to each lubrication fi tting until grease emerges from the
removed lube fi tting hole in a steady fl ow or until a maximum of 1 fl . oz (30
ml) of grease has been applied, whichever comes fi rst.
(4) Install each lubrication fi tting and tighten until snug.
(5) Install a lubrication fi tting cap over each lubrication fi tting.

[Geico266]

Thanks Walt.


Does the grease have a shelf life? Is it normal to look like wax?

[Walt]

Greases normally have a "shelf life" of 3 years at which point they "should" be retested, however they don't have an official expiration date as far as I'm aware. Check the grease can for a DOM (date of manufacture), if it's more than 10 years old I would dump it.

If the container is air tight, clean and not contaminated the useful life is probably longer than the 3 year retest date. If the grease has been stored in a grease gun for a number of years (non air tight container) it would probably be prudent to clean and refill with fresh grease.

[Pat Stewart]

Item 1 in Walt's first post is very important. I actually remove all the zerts except the one I am using. Many people have messed up their prop by just applying grease at each zert without removing the other zerts first.

Pat

[Walt]

Pat is correct this is VERY IMPORTANT, you should remove the trailing edge blade fitting and then apply grease slowly at the leading edge fitting.

After doing some grease gun research, the best I can come up with on delivery for the standard hand operated lever grease gun will deliver approx 1 gram per stroke which works out to about 1oz/28 strokes, for a pistol style gun it takes approx 1oz/40 strokes.

Personally I like to pump very slowly and flush the hub till I see the old grease purged and the new grease start coming thru. If you do it SLOWLY and when the prop/grease temp is warm there is very little risk of blowing a seal. Don't do this in the winter when the grease is thick!

[Ironflight]

Originally Posted by Walt

{quoting the Hartzell Manual} In-service lubrication: Using a hand operated grease gun, apply approved grease to each lubrication fitting until grease emerges from the removed lube fitting hole in a steady flow or until a maximum of 1 fl . oz (30ml) of grease has been applied, whichever comes first.

This part has always been a little bit controversial - do you put in a certain AMOUNT of grease, or put it in until it comes out the opposite grease fitting hole? The 115N version of the manual for the compact hubs says (in a note) that "1 fl. oz. (30 ml) is approximately 6 pumps with a hand-operated grease gun". I actually called Hartzell one time and was told to stop after six pumps, regardless of whether or not you get anything out the back side (which goes along with the statement "whichever comes first") but I know many who say "put it in until you see it come out the other side".

The problem is that Hartzell really warns about over-lubrication, so I hate to put in too much, yet I also don't want to put in too little - and it can sometimes be hard to tell if you are getting full "squirts" with each pump.

This topic hasn't been discussed here for awhile...any good inputs? (I have always done six pumps and stopped because of the warnings about over-filling. Well, maybe I've put in an extra pump or two if one feels "funny"...)

Paul

[Walt]

Paul.. I think you need to do a grease gun test and see how many stroke it takes to actually pump the 1 oz

The specs I found above on delivery were from Groz the makers of high quality grease guns. Maybe Hartzell is using some kind of Super Grease Gun.

[dgate80]

Originally Posted by Ironflight

This part has always been a little bit controversial - do you put in a certain AMOUNT of grease, or put it in until it comes out the opposite grease fitting hole? The 115N version of the manual for the compact hubs says (in a note) that "1 fl. oz. (30 ml) is approximately 6 pumps with a hand-operated grease gun". I actually called Hartzell one time and was told to stop after six pumps, regardless of whether or not you get anything out the back side (which goes along with the statement "whichever comes first") but I know many who say "put it in until you see it come out the other side".

The problem is that Hartzell really warns about over-lubrication, so I hate to put in too much, yet I also don't want to put in too little - and it can sometimes be hard to tell if you are getting full "squirts" with each pump.

This topic hasn't been discussed here for awhile...any good inputs? (I have always done six pumps and stopped because of the warnings about over-filling. Well, maybe I've put in an extra pump or two if one feels "funny"...)

Paul

When I purchased a brand new prop from Hartzell I had a ton of questions, they were very good about tech support over the phone. I was also told that the "six strokes" method was the way to go. The tech also said, "off the record", that after greasing at 10 hours TIS and 100 hours TIS, that if one never greased it again things would be just fine, that more props have been damaged from over greasing and none have evern had a lube deficiency from lack of grease. Props IMHO are kinda sealed units and once grease is installed and in the working areas, it lasts a long long time.

Taking all that in, I now do the six pumps every 2nd year at annual time, flying 125 hours a year.

-- Don Gates

[Ironflight]

Originally Posted by Walt

Paul.. I think you need to do a grease gun test and see how many stroke it takes to actually pump the 1 oz

The specs I found above on delivery were from Groz the makers of high quality grease guns. Maybe Hartzell is using some kind of Super Grease Gun.

Yeah, that's exactly my problem with the "6 pumps" rule Walt ....what makes them think every gun is alike?! They obviously aren't....

Interesting thoughts from Don's post!