The National Transportation Safety Board said yesterday that its investigators examined the engines of the Northwest Airlines jet that crashed in Detroit and found no evidence that they caused the accident.

Engine failure on the McDonnell Douglas MD80 jet, which crashed Aug. 16 and killed 156 people, was one of the early theories investigators were looking into as a cause of the disaster.

"There was nothing in the disassembly of the right or left engine that would indicate an internal failure prior to impact," NTSB spokesman Alan M. Pollock said.

At a news conference shortly after the accident, NTSB member John K. Lauber had said authorities had found no evidence in either engine of an uncontained failure, in which parts would have flown out of the casing.

Pollock said that until a report on the accident is issued in October, the board will not definitively rule out the engines as a cause of the crash of Flight 255. A final NTSB report on the entire accident is expected early next summer.

Investigators are examining indications that the crew of Flight 255 had not properly set the aircraft's flaps for takeoff.

The airliner had two JT8D-217 engines on the rear of its fuselage. The JT8D-217 is one of the most widely used jet engines.

"In the sense that NTSB still has a long way to go, we're pleased that at this stage their investigation of the engines has indicated there was not a failure," said spokesman Jim Linse of Pratt & Whitney, the Connecticut-based aircraft engine manufacturer that built the plane's engines.