Thanks. That makes sense. I forgot that detail.
Glad I could help.
"A single source supplying both aircraft and crew to provide transportation to someone else in exchange for any form of compensation requires an operating certificate unless it's an activity excepted..."
is really the controlling concept for the entire subject. In writing, it might even be called the "topic sentence."
The problem with the subject that both "single source" and the "unless" can get complicated. "Single source" gets us involved in "operational control" analysis and the "unlesses" can be so detailed that two things that look the same can be treated differently based on how structured.
The "flight department company" concept is a good example because it's relatively simple, Two scenarios with one difference.
(1) Very Big Company, Inc. has a flight department. It owns a King Air. The flight department hires pilots, takes care of maintenance and scheduling. If a Very Big Company, Inc officer wants to travel in the King Air on business, they have to call the flight department to make arrangements. The aircraft is only used for Very Big Company Inc travel.
(2) Everything's exactly the same as in (1) except, in order to segregate assets and liabilities and for tax reasons, Very Big Company, Inc. created, VBG Air, LLC to be the flight department and put the King Air in its name. VBG Air, LLC is a single-member LLC; Very Big Company, Inc owns 100% of the membership.
(1) is Part 91. (2) is Part 135.