What's in a name?
Rarely is there any friction, on most occasions first names are used although being addressed in a non obsequious manor as captain is not uncommon. Rest assured you non-pilot types that the term 'captain' doesn't make the chest swell with pride nor add rectitude to one's already exemplary posture. Call me sir and I'll wonder as to what is wrong with you.
While we are on subject of titles - who is this engineer to whom the thread refers? Engineers design aircraft whereas subsequent maintenance on the finished product is undertaken by a mechanic. A tiny bit naughty and misleading of some of you to confuse the two.