SWAMPSCOTT-A Nahant man remains hospitalized at Beth Israel Deaconess Medical Center following a fall at a construction site in Swampscott on Wednesday.According to police reports, Francis Cullinan of Nahant fell and injured his back when he was descending an unfinished flight of stairs leading from the attic to the lower level of a new home under construction at 44 Windsor Ave.The police report states there was some type of plywood at an odd angle in the stairwell when rescue workers arrived at the scene.Detective Sgt. Tim Cassidy said Cullinan was airlifted to Beth Israel Deaconess Medical Center. Hospital Spokesman Zinee Marchoudi said Cullinan was listed in good condition on Thursday afternoon but would not release any additional information on his condition.Dandreo Brothers Masonry, who owns the property, is also the contractor on the project. Calls to Dandreo Brothers Masonry, which has offices in Lynn, were not immediately returned on Thursday.Occupational Safety and Health Administration Spokesman John Chavez confirmed the accident is still under investigation and said OSHA policy is not to discuss an active investigation.OSHA is still investigating another construction accident that occurred in town last month. In October, three men were roofing a new house at 41 Buena Vista St., when a bracket supporting their scaffolding broke through a wall, causing them to fall.