Ruben,

I AM old and that term has likely been around long than I. Could be that it is in wider use in some sectors or parts of the world than others.

http://en.wikipedia.org/wiki/Propeller_head

Quote
The term propeller head (sometimes abbreviated PropHead) also refers to a person (usually an engineer of some type) who is employed to do a technically demanding job. It appears to derive from a "head in the clouds" type stereotyping of more technically aware people (compare with geek, nerd, absent-minded professor, etc.) or possibly from the propeller beanie. The term may be meant or taken as slightly pejorative but is usually meant with some respect.


I use the term to say someone is smart and far more proficient in a given field than I.