Yet Another Grease Question

[corn_flake]

I was out at the hangar tonight to "get to know my Mooney" better.   . I had the belly skin removed just check things out and noticed couple of zirc fitting.  After reading the service manual, I think Aeroshell 22 suppose go into those, but can any one confirm? (Picture 1).  Also noticed cream color grease on elevator trim screw (picture 2).  Does any one know what type of grease suppose to go into the trim screw?  Of course there is the all too important actuator.  Is there a way to grease it without removing the unit?  (Picture 3).  

 

[M20F]

Not all answers but a good read on topic

 

[MB65E]

4 hours ago, corn_flake said:

I was out at the hangar tonight to "get to know my Mooney" better.   . I had the belly skin removed just check things out and noticed couple of zirc fitting.  After reading the service manual, I think Aeroshell 22 suppose go into those, but can any one confirm? (Picture 1).  Also noticed cream color grease on elevator trim screw (picture 2).  Does any one know what type of grease suppose to go into the trim screw?  Of course there is the all too important actuator.  Is there a way to grease it without removing the unit?  (Picture 3).  

 

What model M20? I’m not sure all versions have those zirk fittings there on the belcranks. A/S 22 will work great there. Looks like somebody used lubriplate on the trim actuator. Unknown on what’s on the gear actuator. 

-Matt

[cliffy]

There is a full lubrication chart with all the call outs in the maintenance manual available as a download on this site.  

[PT20J]

When you look at the Mooney Maintenance Manuals you will find obsolete Mil Specs called out.

MIL-G-81322 is now MIL-PRF-81322G and is Aeroshell 22 (amber color) or Mobilegrease 28 (red color). 

MIL-G-3545 is now obsolete but is Aeroshell 5

MIL-G-23827 is superseded by MIL-PRF- 23827C Type I (Metallic soap thickener, Aeroshell 33, Mobilegrease 33) and Type II (Clay thickener, Aeroshell 7). Don't mix Type I and Type II, the thickeners are incompatible. Use AS 7.

Skip

[PT20J]

I'm curious what @mooneydoc and others are using:

Wheel bearings: SHC 100 or Aeroshell 5?

MIL-PRF-81322G: Aeroshell 22 or Mobilegrease 28?

Landing gear actuator ball screw? This is confusing since Mooney used several manufacturers. Mine is an Eaton. The M20J Maintenance Manual calls for GREASE(Dukes) and lists MIL-G-23827 and Mobil #27. Mobilgrease 27 doesn't seem to be made any longer but was lithium soap thickened, so it is probably superseded by Mobilegrease 33 which is a MIL-PRF-2387C Type I grease.

Skip

 

 

[RLCarter]

4 hours ago, PT20J said:

I'm curious what @mooneydoc and others are using:

Wheel bearings: SHC 100 or Aeroshell 5?

MIL-PRF-81322G: Aeroshell 22 or Mobilegrease 28?

Landing gear actuator ball screw? This is confusing since Mooney used several manufacturers. Mine is an Eaton. The M20J Maintenance Manual calls for GREASE(Dukes) and lists MIL-G-23827 and Mobil #27. Mobilgrease 27 doesn't seem to be made any longer but was lithium soap thickened, so it is probably superseded by Mobilegrease 33 which is a MIL-PRF-2387C Type I grease.

Skip

 

 

I think you meant @M20Doc , mooneydoc hasnt been on since he signed up in Jan. of 2014

Edited June 30, 2019 by RLCarter

[Guest]

From the J manual, Lubriplate 630AA for the landing gear actuator ball nut.

Mobil 28 for wheel bearing, but it does make a mess when it oozes out.

Clarence

[PT20J]

1 hour ago, M20Doc said:

From the J manual, Lubriplate 630AA for the landing gear actuator ball nut.

Mobil 28 for wheel bearing, but it does make a mess when it oozes out.

Clarence

Thanks, Clarence! I missed the double entry for the ë symbol. 

Do you generally prefer Mobilgrease 28 over Aeroshell 22? 

Skip

[corn_flake]

My Mooney is a 69 M20E.  Thanks for all the information.  Look like AS 22 is the right grease to use for the belcranks.  While the service manual I have for M20E (last revised 1985) shows Lubriplate 630AA with 10% Moly mix, the grease that's on my ball screw now doesn't look like have much moly mixed in it.  I was under the impression that even 5% moly would turn any grease into black paste....

Edited October 18, 2019 by corn_flake

[PT20J]

11 hours ago, corn_flake said:

My Mooney is a 69 M20E.  Thanks for all the information.  Look like AS 22 is the right grease to use for the belcranks.  While the service manual I have for M20E (last revised 1985) shows Lubriplate 630AA with 10% Moly mix, the grease that's on my ball screw now doesn't look like have much moly mixed in it.  I was under the impression that even 5% moly would turn any grease into black past....

I discussed this with Robert at LASAR. They mix Aeroshell 5 with 10% MoS₂ which is what Dukes specifies for the actuator gearbox. Apparently there are no commercial greases available with greater than 5% MoS₂. They use the same grease on the ball screw. They sell the mixture: https://lasar.com/misc-supplies/special-blend-grease-dukes-grease

For the landing gear zerks, Mooney specifies MIL-PRF-81322G which is either Aeroshell 22 or Mobilgrease 28. A number of sources I've checked believe that Mobilgrease 28 tends to have less separation of the oil and thickener, but some don't like it because it is dyed red.

For wheel bearings, the most commonly  used grease is Aeroshell 5. Mooney specifies MIL-G-3545 which is obsolete but Aeroshell 5 met this spec. Cleveland recently switched to recommending SHC 100. Since MIL-G-3545 was superseded by MIL-PRF-81322, either Aeroshell 22 or Mobilgrease should also be acceptable.

Ignoring any additive packages, grease comprises oil and thickener. Oil is either mineral-based or synthetic. Thickeners are either clay or soap (most common soap is Lithium). Most older aviation greases are clay thickened because clay provided better high temperature performance. Most non-aviation greases are Lithium soap thickened. There can be compatibility issues, so greases of different oil types and/or different thickener types should not be mixed. If you don't know what grease was used previously, it should be completely removed before adding new grease.

Skip

[cliffy]

If you want to learn about the incompatibility of different greases for different jobs just look up the crash of Alaska Airlines MD80 near Ventura CA  

[jaylw314]

15 minutes ago, cliffy said:

If you want to learn about the incompatibility of different greases for different jobs just look up the crash of Alaska Airlines MD80 near Ventura CA  

Interesting, but looking up the Wikipedia link for the AS261 crash, it suggests the NTSB concluded the use of Aeroshell 33 instead of Mobilgrease 28 was not a contributing factor to the jackscrew failure.  At least, according to the Wikipedia article.  I didn't read the full NTSB report.

[PT20J]

Here's the short version. There was discussion about incompatible greases but I think the conclusion was that there wasn't much grease at all on the failed jackscrew.

A01_41_48.pdf

[Guest]

I thought that the continued stretching of the maintenance interval and lack of grease caused failure of the jack screw and nut connection?

Clarence

[PT20J]

Actually, now that I think about it, if Mobilgrease 28 was good enough for Douglas to specify for the trim jackscrew on the DC-9 it should be good enough for the ballscrew on the Mooney landing gear actuator. I understand the that the Dukes units with the 20:1 gears are problematic and need the moly-fortified grease, but the ballscrew should get along fine with just Lubriplate 630-AA. As Clarence pointed out, the Service Manual calls out Lubriplate for this application. It says it's permissible to use the Dukes moly compound as LASAR does, but it doesn't say it's required or particularly advantageous.

Skip

[cliffy]

It was also found that an incompatible grease was used compounding the wear. 

[PT20J]

42 minutes ago, cliffy said:

It was also found that an incompatible grease was used compounding the wear. 

Don’t mean to be argumentative here, but that is not factually correct. Quoting from the NTSB final report findings:

21. Alaska Airline’s use of Aeroshell 33 for lubrication of the jackscrew assembly, acme screw thread surface finish, foreign debris, and abnormal loading of the acme nut threads were not factors in the excessive wear of the accident acme nut threads.

Full report at: https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf

Skip

[amillet]

I had no idea there could be so many choices of grease as I greased the balers and other farm machinery 50 years ago.

[corn_flake]

Any suggestions on how to get the grease into the actuator ball screw?  

[jetdriven]

Retract gear on jacks.  Wipe exposed screw with aero shell 64.  Extend and retract. The repeat.  Don’t forget the flap jack screw.  And the tail trim actuator screw.