Cleaning and lubrication of manual elevator trim chain and gear train

[Vance Harral]

With the recent spate of trim issues, I'll be taking an extra-close look at the stabilizer trim system on our 1976 F model during the owner-assisted annual we start next week.  Just seems like a good idea.

No electric trim in our airplane, everything is manual.  The jack screw and hinges at the tail end aren't especially difficult to inspect and lube once you get the boot out of the way, I do that every annual.  The shafts and universal joints which connect the tail components to the cabin end of the system are easily accessible for inspection and lube as well.  That leaves the cabin end: the trim wheel itself, and the chain and gear train which connect it to the first segment of the trim shafts.

While it's not technically impossible to access these components (I try to get some grease on the chain at every annual), most of the moving parts are behind supports or inside what the parts manual calls a "gear box assembly".  I've never had this apart or really lubricated it well during the years we've owned the airplane.  I have a sneaking suspicion the gearbox and gears/bearings/etc. are full of old dried grease, sludgy lube, and dirt.  In a perfect world, I'd like to do the same sort of inspect/clean/re-lube we do on our electric landing gear actuator gearbox: remove the assembly, open the covers, flush everything with solvent, inspect, and re-lubricate.  But this seems like a difficult job with the trim gearbox, prone to causing a maintenance-induced failure.

What do the rest of you out in MooneySpace do with this part of the trim assembly?  Remove it for a full clean/re-lube?  Just shoot some lube in whatever access hole you can find with a straw?  My parts and service manuals don't say anything about it that I can find.  Would like to hear about best practices from those in the know.

[cnoe]

The chain is easily accessible by removing the plastic cover between the seats in the cockpit. More can be lubed when under the plane beneath the belly skins.


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[cliffy]

I've had mine out for clean and lube  It ain't that big of a deal.

[Vance Harral]

Cliff, did it all come apart with conventional bolts and screws, or is anything riveted?

[cliffy]

Its been a few years but I don't remember anything that stands out.