By Dan Whitcomb

LOS ANGELES (Reuters) - Former New York Mets star Lenny Dykstra pleaded not guilty to bankruptcy fraud charges on Monday and was ordered to stand trial on August 9.

Dykstra, best known for helping the Mets win the 1986 World Series, was indicted by a federal grand jury in Los Angeles in May, accused of stealing or destroying some $400,000 in property that was part of his bankruptcy case.

The 48-year-old former ballplayer faces unrelated charges in state court stemming from what Los Angeles County prosecutors say was a scheme to lease cars using phony business and credit information.

His accountant, 27-year-old Robert Hymers, and friend Christopher Gavanais, 30, were also charged in the state case.

Dykstra, nicknamed "Nails" during his playing days, remains in custody on that state case in lieu of $500,000 bond pending an arraignment and bail hearing on Thursday.

The federal court indictment charges Dykstra with scheming to defraud his creditors by declaring bankruptcy in 2009, then stealing or destroying the furnishings, artwork and sports memorabilia from the $18.5 million mansion that he bought from hockey great Wayne Gretzky.

The former athlete, who was indicted on 13 counts of bankruptcy fraud, obstruction of justice and other charges, faces a maximum sentence of 80 years in prison if he is convicted at trial.

He faces up to 12 years behind bars if convicted in the state case.

Dykstra spent 11 years in the major leagues, mostly as an outfielder for the Mets and Philadelphia Phillies.

He is best remembered by Mets fans for the 1986 season, when he struck a walk-off game-winning home run in Game Three of the National League Championship Series.

In Game Three of the 1986 World Series, he also hit a key lead-off home run, sparking a comeback by the Mets from a 2-0 series deficit to win the championship over the Boston Red Sox

(Editing by Peter Bohan)