Are engineers stereotypically excellent writers?

When I first started out, I had a job as a typist for an engineering unit.  None of them were particularly good writers.  One fellow in particular, one of the management team, would give me letters to type - and they were incoherent.  A single letter would violate most of the basic rules of the English Language.  Lots of sentence fragments, run-ons, etc.  I would just rewrite the whole thing so that it made sense to me, and send the finished copy back to him for signature.  He always signed it. 

if you mean their penmanship, at one time that was true. They, like architects, would need to label drawings very clearly so it could not be misinterpreted. Being off be a fraction could cost a small fortune, and some not so small fortunes. With the computer writing things now that isn't the case.

If you mean from a grammatical sense, most are not. They don't tend to think that way. They work with numbers and abbreviated terms, so they tend to think in those terms.

No.

They tend to be concrete thinkers rather than abstract thinkers.