One system that is on every airplane it the pitot-static system. This delivers pitot pressure to the airspeed indicator and static pressure to the airspeed, altimeter and vertical speed indicator. The static pressure is sensed from a small hole in the side of the airplane. It is important that both these systems be leak free. Leaks can come from tubing joints and also from the cases of the instruments themselves. So I pulled the instruments and the tubing with the intention of having the instruments checked and fixed. As you can see, the airspeed and the VSI are not indication zero and the inside of the altimeter case is fogged up. From the stickers I found on the cases, it has been more than twenty years since they have been serviced. So I took them to the instrument shop for repair. When I get them back, I am going to assemble the system on the bench and check it for leaks before putting it back on the airplane. All it takes is money!

BTW - Happy Birthday to my sister Jean up there on the frozen tundra.