Dennis Hargett, a 38-year-old veteran firefighter was charged with sexually abusing his 10-year-old daughter repeatedly over the past four years.  His daughter complained of the attacks to an aunt on Monday night and she called police.  Hargett, who lives on Hegeman Ave. in Brooklyn and is a member of Engine Co. 235 in Brooklyn, was taken into custody yesterday at the firehouse at Monroe Street and Nostrand Ave.  Hargett was suspended without pay after his arrest, pending further investigation according to a statement from the Fire Department.  The attacks occurred while the girl had visits with her father who is not married to the girl's mother.  She was examined at a local hospital yesterday, police said.