He's a 'mechanical' genius. [=he is a person who is very smart about machines]
He's not 'mechanically' inclined. [=he is not knowledgeable about machinery]
The flight was delayed because of 'mechanical' problems/difficulties.
(..) your cartoon show, dear. Come on, Bart. Kiss the ticket for good luck, not that we need it. Here comes Screwy the mechanical rabbit. - and they're off! - Come on, Santa's Little Helper! - Come on, dog! Go, man, go! It's Whirlwind in the lane, and coming up on the left is Quadruped, (..)1989 TvShow: The Simpsons Title: Simpsons Roasting on an Open Fire Season: 1 Episode 1