The widow of Richard Obenshain, the Virginia Republican nominee for the U.S. Senate who died in a 1978 plane crash near Richmond, has filed suit in federal court seeking $5 million in damages for her husband's death.

The suit, filed by Helen Obenshain in U.S. District Court in Alexandria, alleges that the pilots of the plane, the Chesterfield County Airport and the manufacturers of airport equipment used there were negligent in the Aug. 2 crash.

Obenshain was returning home after a campaign appearance in Winchester when the twin-engine Piper Seneca in which he was a passenger became lost in bad weather at night and went down in trees about a mile from the Chesterfield County Airport.

A study of the crash by the National Transportation Safety Board found that the pilots had little night-time flying experience. A navigational aid at the airport had been out of operation for two days because of a blown fuse.

Though it was never determined who was at the plane's controls at the time of the accident, the suit names both pilots on board. Both men also died. t

One of them, Richard F. Neel of Alexandria, had been active in Republican politics and was donating both his time and use of the plane to Obenshain's campaign. Neel told Obenshain before taking off from Winchester that he was working on his instrument rating.