Being curious and wanting to wrench on the wing, I did the initial inspection. Like Fred mentions, about all you can do is remove the air filter and take a look to be sure the box is not gummed-up. Mine was near pristine clean and even now, when I look in there during my rather infrequent air filter changes, there is no puddled oil residue and not much to go wrong -- unless you goof it up with a cleaner agent. If you are in the apparently significantly large group that insists upon putting more than 4 quarts of oil in the case becuase the dip-stick is cantankerous to read, then maybe you should be prepared to wipe some puddled oil out of the bottom of the box because that is where the excess oil vapors are drawn from the crank case vents to be burned off. Fuel line inspections are similar. Use your nose and eyes to check that out.