Six of the eight U.S. freestyle team members are unbeaten after the first day of competition at the Pan American Freestyle Wrestling Championships, held in Santa Domingo, Dominican Republic on May 19.    Held three of every four years during the non-Pan American Games years, the Pan American Championships features the best wrestlers in North, Central and South America.     The U.S. athletes without a loss are: T.J. Hill (Colorado Springs, Colo./Lions Den) at 119 pounds, Chris Fleeger (Trout Run, Pa./Dave Schultz WC) at 127.75 pounds, Jamill Kelly (Stillwater, Okla./Cowboy WC) at 138.75 pounds, Joe Heskett (Ames, Iowa/Sunkist Kids) at 167.5 pounds, Andy Hrovat (Ann Arbor, Mich./Cliff Keen) at 187.25 pounds and Andy Bowlby (Corvallis, Ore./Orange Crush) at 286 pounds.    Hill had a 3-0 record on the first day, with all three wins by technical fall. Fleeger, Kelly, Heskett, Hrovat and Bowlby all had 2-0 records.    Two wrestlers on the U.S. team suffered losses during the first day:  Ryan Berger (Ill./Unattached) at 152 pounds and Michael Dixon (Ind./Unattached) at 213.75 pounds. Dixon had a 2-1 record, while Berger had a 1-2 record.    The competition will conclude on Sunday, May 20, with preliminaries, semifinals and medal matches.    The qualifying event for the U.S. freestyle team was the University Nationals, which was held in Evanston, Ill. in March.    PAN AMERICAN FREESTYLE WRESTLING CHAMPIONSHIPS  at Santa Domingo, Dominican Republic, May 19  U.S. freestyle team results    54 kg/119 lbs. - T.J. Hill, Colorado Springs, Colo. (Lions Den) - won by tech. fall over Fredy Serrano (Colombia), 10-0; won by tech. fall over Hector Camacho (Venezuela), 10-0; won by tech. fall over Oscar Ruano (Guatemala), 10-0    58 kg/127.75 lbs. - Chris Fleeger, Trout Run, Pa. (Dave Schultz WC) - won by tech. fall over Geovani Ramirez (Guatemala), 10-0; won by tech. fall over Arnel Kernizian (Puerto Rico), 10-0    63 kg/138.75 lbs.  - Jamill Kelly, Stillwater, Okla. (Cowboy WC) - won by tech. fall over Rene Silva (Mexico), 10-0; won by tech. fall over Ferndo Taveras (Dominican Republic), 10-0    69 kg/152 lbs. - Ryan Berger, Ill. (Unattached) - dec. Modesto Ganeros (Argentina), 6-2; lost dec. to Yosmani Sanchez (Cuba), 4-0; lost dec. to Celso Deanda (Mexico), 3-2, ot    76 kg/167.5 lbs. - Joe Heskett, Ames, Iowa (Sunkist Kids) - dec. Paul Harrison (Canada), 6-0; dec. Jose Aguilar (Venezuela), 8-0    85 kg/187.25 lbs. - Andy Hrovat, Ann Arbor, Mich. (Cliff Keen) - won by tech. fall over Enrique Minier (Dominican Rep.), 11-1; won by tech. fall over Fernando Marquez (Brazil), 13-2    97 kg/213.75 lbs. - Michael Dixon, Ind. (Unattached) - dec. Gabriel Palermo (Argentina), 4-3, ot; lost dec. to Wilfredo Morales (Cuba), 5-1; won by inj dft. over Jose Fonseca (Nicaragua)    130 kg /286 lbs. - Andy Bowlby, Corvallis, Ore. (Orange Crush) - dec. Carlos Panaco (Canada), 4-0; dec. Renato Sobral (Brazil), 10-1    Coaches - Bobby Douglas, Ames, Iowa; Mike McArthur, Colorado Springs, Colo.