The fact is that you will not be able to plan for everything so plan for some things.
What I have been doing over the last two years is setting aside $150.00 a month into an airplane maintenance fund. Now I don't want to delude anyone into thinking that $150.00 a month will cover any major aircraft repairs. It won?t. However, So far this has allowed me to have the cash on hand to do every minor repair that has come down the pike: new fairings, new wingtips, new fuel tank gaskets, stainless screw sets, New shimmy dampener, and has also covered the cost of annuals.
The only thing that I have needed to dig deeper into my pocket for thus far was a new NavComm.
I just consider this $150 as part of my monthly aircraft loan payment. I planned this in when I bought the airplane. I figured out what the maximum monthly aircraft payment I could afford was and subtracted $150.00 from that. Then I knew how much airplane I could get and still have a small maintenance reserve. As far as I am concerned the money is gone until something comes up with the airplane. It will surprise you how quick even $150/month grows. When I upgrade I will plan on saving more.
Any major work would come out of our general savings or a short term loan.
So far this has worked well for me.