[KyleTownsend]

Similar to the old real-estate mantra, I would say Engines, Engines, Engines!

Unless you are buying a really loaded creampuff skymaster with recent paint and interior, the engines are going to constitute the bulk of the value of the airplane. And, obviously, they are going to be the biggest "gotcha" if they fail shortly after you get home.

Unfortunately, it is really hard to assure engine health and predict how long they will last. Of course, you can at least tell if the engines are already having serious problems by reviewing the logs, doing a borescope, oil analysis, checking the filters/screens, looking for oil leaks, checking in-flight oil consumption and operating termperatures, etc.

Someone also mentioned a more invasive procedure that I believe I will do as part of my pre-buy. I'm not a mechanic, so I don't know if I have this exactly right. However, it involves removing the rocker-box covers and "rods" ? and going in through these openings to inspect the cam lobes and the ends of the "rods." Apparently, significant signs of pitting, wear, corrosion, etc. in this area would be a good indicator of bottom-end health, which is the big "gotcha" on many older skymasters. Supposedly, this will add about 5 hours of mechanic time to the pre-buy.

Another big "gotcha" is whether the engines have the VAR cranks, heavy cases and wider push-rods. If not, then you may as well budget for a factory remanufactured engine at next overhaul, which adds significantly (6,500+ per engine) to the cost. In corrolary, you must also adjust the purchase price downwards by some amount to reflect this reality.

I suppose the only other "gotcha" that can compare to bad engines is significant corrosion (especially in the wings) and any cracking/weakness at major structural attach points. This can render an airframe virtually worthless.

It's also a good idea to compare the airplane's performance to book in the air, especially if there has been any damage history. If the plane is bent, or significantly mistrimmed, it will show up in the performance (hint: look at the ailoron trim tabs. If they show major deflection in the same direction, watch out).

After these items, you are down to the second tier items which can be expensive, but not a nightmare, such as the gear system, electrical system, avionics, etc.

Well, that's my 2-cents. Good luck to you! Good luck to me!