A Must Have
Incredibly complete. Millions of reference data about almost everything you can think about, plus what you haven't yet imagined you'd need.
I purchased this software by mistake from Van's when I was supposed to order the toolbox sample project, but I'm so glad I did.
The guys at Sacramento Sky Ranch do an amazing job compiling tons of valuable information for anyone dealing with aviation maintenance.
I highly recommend it, and the latest version even has a refurbished interface.
Cheers