Thorp Air Command - T18.net

At conditional a coupla months back, I went to regrease the bird's prop hub, went to the local FBO for a tube of Aeroshell 5, which plackarded on the hub, and what I had used every year to date. All they had was Aeroshell 6, which is the standard grease for hartzell hubs since the late 90s. What harm can it do - it just be grease...??....the local mech saw no harm in it.... Greased up and flew the plane for an hour and noticed a little grease on both blades. Not the first time this has happened. The prop seals have weeped a little on and off since I got the plane. Dry for a year, then a few flights with a bit of grease out 6 inches or so onto the blade, then none for 6 months, rinse and repeat. No consistency and no correlations with temps. Random acts of escaping grease. So then off to Vegas and Rosamond and ack for Tony's keg fiesta. By the time I got back, the hub had deposited what appeared to be the entire 1/4 tube of Aeroshell 6 I had pumped in on the wing roots and the pax side of the wind screen.
Upon then doing the research I should have done previously, it turns out that Aeroshell 5 has a higher viscosity and molecular weight than the 6. The reason Hartzell went to 6 is because it maintains it's lubricity and viscosity at lower temps than does 5. 5 maintains mil-spec to a mere -23F. The 6 is good to -60F (I think). It does not mean that 5 is bad. 5 does not lock up or turn to ice at -23F......it just goes out of mil spec. Yours truly parks his puss fireside at anywhere near those temps. My heater ain't that good.
I greased the prop a couple of weeks ago with Aeroshell 5, pumping 1/4 tube into each side to purge what I could.(Hartzell says best hope is a 30% purge) Flew today for an hour doing formation work with Homey.

No leaks.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

That's interesting Frase.......who da thought.......certainly not me that's fer sure....Dan

Sounds like you need some prop wash too,(wing wash is good also) with all that grease leaking onto the hub and blades. Had my prop over hauled last year and it weeps a little grease as yours did , maybe I need to check into what grease the shop used.

I have some #5 in my bin, Bill.

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Bob Highley
N711SH
SN 835
KLAL

....Youngest Estrogen Offspring Unit texts me from the basement........for some reason I have this picture of you two texting each other from opposite sides of the hangar.....

I think the main lesson here is to use whatever grease is currently in the hub. Different molecular weights and viscosity materials get tossed around the hub (like a centrifuge) differently. In my case, I think the heavier material pushed out the lighter material, but a fizziscist might be able to set me straight on that.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Good visual except I am in Hawaii while Bill maintains the watch on the Florida home front.

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Bob Highley
N711SH
SN 835
KLAL

There you go sacrificing yourself in Wx paradise so the rest of us can revel in the cold and the snow.....

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Fraze, that's the reason I did not point out we were on both sides of mother earth. We were both in sunny climates. It did rain yesterday, so no fly-out for breakfast.