TEAL was a single-type airline for the first 14 years of its existance and it went through three generations of airliners during those 14 years: S.30 Empire Boats, then S.25 Sandringhams, then S.45A Solents.
And during the early part of the 1960s they became a single type airline again with only Lockheed L.188 Electras for about four years.