Transmission Greases

Next comes the discussion of greases and which to use inside the transmissions. The Dukes transmission and its specified grease is a no-brainer but what about the MIL-G-23827 [Aeroshell 7] specified for the Dura? The manuals say “no substitution is allowed in either transmission“. Gear wear is the issue [from lack of service specified annually or 500 hours; or inadequate grease spec – Dura; or normal wear – things do wear out you know]. there are better greases available than the #7 for this application. My point is, use the Dukes grease in the Dura also. If you don’t have that grease at least use the Aeroshell 33MS which may be somewhat easier to get your hands on in short notice. See “ALTERNATE GREASE” discussion.

Read this about Aeroshell 33MS which is a 5% molybdenum disulfide additive [Dukes is min 10%]. i would recommend this grease in your Dura transmission if the Dukes grease is unavailable [get some, the grease is cheaper than the gears!]. FWIW the Lubriplate® MoLith #2 is 2% molybdenum disulfide.

Don’t tell anyone but I use the MoS2 grease on the actuator screw also.

Dukes grease as specified in the Service Manuals. There are 2 Dukes greases found in the Single and Twin SMs; I asked Dukes about this – they are the same specification grease. I no longer stock the Dukes grease.

Transmission service as specified in the Service Manuals. This applies likewise to the flap transmissions; wouldn’t that figure? I’ll wager the flap transmission service is the 2-nd most-ignored service in all of Comanche-world.

Here’s my bet on the 1st place for most-ignored. If you search the SMs you’ll find a note requiring 2000 hour or 7 year repetitive inspections of the airframe requiring headliner removal and upholstery panels. Aren’t you happy to know that? I know, “quit reading”!

• Read special instruction #3 in this Twin Comanche reference
• More Twin Comanche reference specifying the 500-hour [or annually] service interval.
• And Twin Comanche SM section 7-35; inspection process.
• Here is a suggested log book entry.

The brake coil assembly; reference Piper’s P/N 23042-000 & 24948-000. A note concerning the brake coil mounting plate; if transferred from a Dura to a Dukes it may need a little attention. I can provide this component “owner produced“.