Having been invvolved with B727-200Adv VIP on N Reg. Now if the Aircraft TYPE was approved for more than 19 seats Part 125. If TYPE approved with less than 19 Seats Part 91. Company sold the B727-200Adv as even though now in only 19 seat config was approved for more than 19 therefore required to be Part 125
. The Boeing BBJ is sold as different to a 737- converted to VIP and therefore only certified at 19 Seats and Part 91 compliant
.
As new owner of 727 just moved onto Cayman Reg.