Eight airplanes carrying passengers made emergency or unscheduled landings Thursday and yesterday as crew members smelled smoke, spotted fuel leaks and noticed other potentially dangerous conditions, authorities said.

In New Jersey, Eastern Airlines Flight 201 from Boston to Kansas City made an unscheduled landing at Newark International Airport yesterday after the pilot smelled smoke in the cockpit.

The plane carried 53 passengers and took off later in the afternoon after workers discovered no problems.

Also in New Jersey, two Continental Airlines flights from Newark, one heading for Chicago and another to St. Petersburg, Fla., returned to the airport after takeoff.

Chicago-bound Flight 635 returned when the pilot saw a warning light indicating that one of the plane's engines was leaking air, spokesman Jim Brigance said from the airline's headquarters in Houston.

Flight 679 from Newark to St. Petersburg experienced "engine problems after some distance," Brigance said. He would not say what the engine trouble was nor would he disclose how far the plane had flown.

In Atlanta, a fiberglass panel flew off the wing of Eastern Airlines Flight 711 bound for Las Vegas shortly after takeoff, but the plane returned to Hartsfield Atlanta International Airport without incident.

In Louisiana, Delta Flight 423 from Atlanta made an unscheduled stop yesterday because an oil pressure light went on, airline spokesmen said.

The 757 jet with 76 aboard landed safely at Shreveport Regional Airport.

No one was in danger and no engines went out, according to Delta Airlines spokesman Bill Berry in Atlanta.

He said the plane reboarded passengers for the flight to San Diego after mechanics found no problem.

A cargo jet sustained substantial damage yesterday when it skidded off a rain-slickened runway in Chicago shortly after aborting takeoff, a Federal Aviation Administration spokeswoman said.

There were no injuries aboard the plane at O'Hare International Airport.

In New Mexico, an American Airlines jet was forced to make an emergency landing Thursday in Albuquerque when one of its two engines failed.

Flight 35, with 139 passengers, was en route to Los Angeles from Dallas. The flight was canceled and passengers were rerouted to other airplanes.

"There was no disturbance in altitude," said Sondra Byington, an airline spokeswoman.

"Most likely the passengers didn't even notice a difference."

Passenger Hal Waldman of Dallas said one of the flight attendants began crying when the pilot announced the engine had failed and an emergency landing was in order.

The plane, a McDonnell Douglas MD80, is identical to the one that crashed in Detroit on Sunday.

Also on Thursday, a Northwest Airlines jet bound for Memphis and Houston had to turn back to Philadelphia International Airport after crew members saw fuel flowing from a wing tip, and a Piedmont Airlines flight had to make an unscheduled stop in Syracuse, N.Y., after a cockpit light went on indicating problems with the landing gear.