I tried searching the forum for an answer but the search did not function.

What is best for lubricating the bushing where the control column passes through the instrument panel?

I know the Maintenance Manual states "graphite-based lubricant" but that sounds messy and possibly problematic if the graphite got into electronics and/or on clothing.

Without lubrication, it's sticky and problematic in the flare!

Thanks,
Jim
M4 Owner

It shouldn’t really need lube. It doesn’t need to be so tight that it binds. Also check behind panel and verify that it’s not a wire bundle or something binding on the column at full aft.

If no wires are binding, I would take out the yoke and massage the bushing with a file or similar. The hole needs to be a little wonky since the yoke goes up at full aft.

Just like the similar but larger bushing on the Piper Cherokees a little slick stuff really makes a difference. Anything from WD40 to light motor oil works. I really like a product called Boeshield T9. Dries slick but with a waxy base and stays on there. Great for control cables too.

I usually get a couple drops of engine oil on my finger and wipe the column down and cycle it. Makes a massive difference, I mean massive.

Motor oil works pretty good, every few months.

Not sure it applies to the M4, but there is a Service Letter for the M5 specifying a wedge shaped spacer behind the panel for the throttle and prop control. It increases the clearance between the control column sprockets and throttle/prop control shafts at full aft column movement.

I think it became an issue when vernier throttle controls were added but not certain on that. My M5 didn’t have the spacers when I got it and there was some resistance at full aft movement. Working the ailerons at full aft column, you could feel the chains rubbing the throttle shaft.

I’ve also seen insulation wadded in tight around the aileron or elevator cable bind on a turnbuckle at full deflection. Worth having a look at the whole control routing.

Not sure about the graphite lube, what type etc. I suspect that is specified because it will not degrade the nylon bushing mounted in the panel.

Kirk

The Forum search engine seems to have a bug when you search for the word "lubrication". It sends you to a blank page. Any other mis-spelling of the word sends you to the normal no-hit page. Please let me know if you find other search terms that don't work so I can create a list.

Wow, I never imagined there would be 5 hits when you search “banana”, but there are.

So… checked that one for ya. It’s good!

Kirk

Thanks for the advice, everyone.

I took some avgas and wiped the somewhat sticky crud off the chrome yoke tube and it slides now pretty well through the bushing.