Rust in engine

I was checking out my 540 with a cheap bore scope. Cylinders all look good and I'm rotating the engine on a stand with about 12 quarts of oil in it. But I found rust in this cross bar inside the front propeller oil shaft (I think, I don't know what it's called) and now I'm worried. I think this supplies oil to the shaft but again I'm not sure. Is this something to worry about, aside from fogging it and finding the darn cap is there anything I should do?

It supplies oil from the nose bearing to the propeller. I would fog it. if your engine is on a stand and not installed, imho you should not be rotating it all you are doing is wiping whatever oil you have on surfaces off. The only remedy that I can think of is to fill the engine with oil or if your stand will allow turn it upside down, after closing off any ports ,holes that would let oil leak out, and coat all those parts you have been wiping the oil off of.
Good Luck,
Mahlon

By "rotating" - are you referring to turning the prop/crankshaft, or rolling the entire engine assembly through a roll on a rolling engine stand, and not moving the prop flange with respect to the engine case?

The first is not a good idea. The second would be acceptable.

by rotating I mean turning the crankshaft. if turning the engine upside down as a unit.. great, good practice.
Good Luck,
Mahlon

Yes rotating the engine on its stand as a whole, I know about not rotating the crank and it hasn't moved since I got it. I've been turning the engine upside down and tilting it forward to keep the cam coated, just saw this rust and was worried so hopefully it isn't an issue.