Investigators are trying to determine why a United Airline jet's landing gear failed to deploy yesterday as it approached Newark Airport the malfunction forced passengers to crouch in their seats and brace for a crash before the pilot touched down safely on the runway. The FAA says the plane's right landing gear didn't extend even though its nose and left landing gear did. The emergency landing closed Newark for about 20 minutes yesterday. United says it's determining the extent of the damage to the plane.