A federal appeals court yesterday ordered a new trial in the $47.7 million civil right suit over a 1969 police raid on the apartment of Black Panthers Fred Hampton and Mark Clark.

The original 18-month trial in U.S. District Court, which began Jan. 5, 1976 and ended June 20, 1977, was the longest in the history of the federal court system.

A three-judge panel of the 7th U.S. Circuit Court of Appeals in Chicago handed down a 122-page decision reversing the actions of trial Judge Joseph Sam Perry in dismissing all 28 defendants in the suit.

The appellate court said 24 defendants, including former Cook County sate's attorney Edward V. Hanrahan, would have to strand trial again on all or some counts. It upheld directed verdicts of acquittal against four police officials, and agreed in part with Perry's ruling against two other officers.

Hanrahan, who is now in private law pracitce, said he would not comment on the fuling until he has seen a copy of the court order.

The families of slain Panther leaders Hampton and Clark, as well as seven survivors of the raid, filed suit against Hanrahan and 27 other law enforcement officials and policemen.

Police attached to Hanrahan's office killed Hampton, 21, and Clark, 22, in a predawn raid Dec. 4, 1969, on the West Side apartment. Four other persons were injured.