The phrase "a principal partner" is correct and usable in written English.
It can be used to refer to a key or leading partner in a business or collaborative context.
Example: "In our new venture, we are excited to announce that Jane will serve as a principal partner, guiding our strategic direction."
Alternatives: "a key partner" or "a leading partner".
I was a principal partner in Big Feats!
Mrs. Carr, 39, is a principal partner in Bliss, Gouverneur & Associates, a Manhattan public relations firm.
(He quickly thereafter became a principal partner of the ballerina Alexandra Danilova).
BAE Systems, Britain's leading defence contractor, is a principal partner in the project led by Lockheed Martin.
He began his advertising career as an art director at Douglas Simon and joined Delahanty, Kurnit & Geller as a principal partner and creative director.
"Bush beats Gore hands down on accountability," said Amy Wilkins, a principal partner of the Education Trust, a nonpartisan organization that monitors policies affecting poor children.
Mr. Rovinescu, a lawyer who has worked on a number of restructurings, is a founder and principal partner of a Canadian investment banking firm, Genuity Capital Partners.
Accel Partners, whose principal partner, Jim Breyer, invested in the start-up seven years ago, holds 201.4 million shares.
Monique Izzi, daughter of an Italian father and a Cambodian mother, was his principal partner from the late 1950s.
For Britain, the Iraq conflict ended with the withdrawal of the last British troops from their base in the southern city of Basra this July, after six years as the United States' principal partner in an occupation that cost the lives of 179 British soldiers.
In late May the buildings were formally turned over to the consortium, whose principal partner is the Settlement Housing Fund, a housing development group, and includes neighborhood and tenant groups.
