An Eastern Airlines jetliner with 60 people on board rolled into the mud at the end of the main National Airport runway yesterday morning after the pilot stopped a takeoff. No one was injured.

Eastern Airlines officials said that a part broke in one of the Boeing 727's three engines as the plane was rolling north on the runway.

The pilot, Capt. C. F. Sexton, was just at the go, no-go point in his takeoff roll (probably about 140 miles an hour) when a warning light went on in the cockpit. Sexton elected to stop the takeoff.

Although it had been raining, there was no hydroplaning or slipping on the runway, experts said. Sources estimated there was about 2,700 feet of runway left when Sexton's braking maneuver began. The runway is 6,870 feet long.

The nosewheel of the plane rolled off the end of the runway onto the embankment next to the Potomac River and right main landing gear stuck in the mud. All passengers left the plane through the rear door. Emergency chutes were not used.

The runway was closed for about an hour and some flights were diverted to other airports.

An Eastern official said that an inspection of the engine late yesterday showed that, although a part had failed, the engine would have been able to continue delivering power. There was no other damage to the plane.