The United Airlines DC10 that was forced to make an emergency landing at Baltimore Washington International Airport Sunday is scheduled to carry passengers again this morning after having a defective engine replaced, airline officials said.

Airline officials and federal investigators said yesterday they have not yet determined what caused the CF6 turbojet engine on the plane to fail shortly after takeoff Sunday morning, but said the problem was not unusual.

The plane was fitted with a new engine yesterday and was scheduled for a flight leaving BWI at 8:23 a.m. today for chicago, United spokesman Jim Linse said.

"I would say something like this probably happens about once a day on a plane somewhere in the United States," Linse said of the engine failure, which resulted in the DC10's returning to BWI 20 minutes after takeoff Sunday without incident. 'If this weren't a DC10 plane, it wouldn't even make the newspapers."

Investigators from the Federal Aviation Administration and National Transportation Safety Board said yesterday that blades from a rear propeller wheel on the rear of the failed engine had snapped off and been shot through the engine's exhaust, scratching and nicking a wing flap.

In addition, they said, it appeared that blades on another propeller assembly near the engine's fuel combustion chamber also had been damaged. But they said they would not know what caused the problem until the engine was transported to United's plant in San Francisco and taken apart.

The cause, officials said, was unrelated to engine support problems that prompted the FAA a ground all domestic DC10s for 37 days recently after the crash of United DC10 in Chicago.

"It could have been a manufacturing defect, or a weakness in the metal of the blades," said FAA spokesman Fred Ferrar. "But there is not way of knowing for sure until the engine is opened up."