Two local businessmen are working together to preserve pieces of a historic barn as it comes down. The Richardson family, whose Tyngsborough roots go back generations, sold their Locust Avenue barn years ago to developers. Now owned by Hayward Smith of Enright LLC, the landmark was deemed by a structural engineer to be too decayed to be restored. Demolition is being done delicately by Jim Fisette of Fisette Excavation Inc., who is hoping to save wood from the barn to use to build a house in New Hampshire and who remains connected with the Richardson family through the process, which is expected to be completed in March. Smith said he may choose to develop the commercial property.