Six years had passed since Will Simpson last rode a horse that qualified for a Grand Prix competition at the Washington International Horse Show. That was before this year's show and before he saddled up with Herban.

Last night the 26-year-old rider from Keswick, Va., skillfully guided the 10-year-old French-bred stallion over a 13-obstacle course to win the $7,500 Sunkist International-Open at Capital Centre.

Herban, owned by Cabin Branch Farm of Marshall, Va., took the course, including a set of twisting double jumps and a water jump, in a faultless 48.84 seconds. He was the seventh of 31 entries to take the course, which proved too tough for even some of the sport's top riders. For instance, Barney Ward on Walito and Norman Dello Joio on Ardennes -- who either faulted out or left the course after their mounts refused to jump.

The victory for Simpson was his second in as many efforts aboard the stallion this week. On Sunday night, Herban kicked off the eight-day show with an impressive win in the $7,500 Cellular One speed class event.

"He's coming out like gangbusters," said Simpson. "He's nothing but great. When he concentrates real hard on the jumps, its real easy to win classes."

The victory put Simpson into the lead of the national rider standings with 14 points, to Rodney Jenkins' 12. Both are competing in the show as individuals, not as team members.

Wellington, ridden by Canadian Equestrian Team member Hugh Graham, took second in the Sunkist event with a clean 50.01 clocking. Stefan Schewe, riding for the Federal Republic of Germany, guided Otto to third in 51.67 without fault, and U.S. Equestrian Team representative Katie Monahan of Middleburg, Va., rode Matterhorn to fourth place in 53.53. Monahan's original time of 48.53 was the fastest on the course but five seconds were added for a knockdown.

Simpson plans to ride Cabin Branch's Jolly Good in Friday night's power jumping class, the Puissance. Recently the horse broke the world wall record when he cleared a 7-foot-9 1/4 indoor jump in Cincinnati.

The United States leads the International team standing with 31 points. Germany has 20 and Canada 14.