Only one of planes listed in Harbor Air’s fleet is a piston: https://www.harbourair.com/about/aircraft-fleet/
And that one is the one they're retrofitting with an electric motor
https://www.businessinsider.com/magnix-all-electric-cessna-g...
Only one of planes listed in Harbor Air’s fleet is a piston: https://www.harbourair.com/about/aircraft-fleet/