Passengers and crew on a Northwest Airlines flight escaped without injury when the plane's main landing gear collapsed as it arrived at Minneapolis/St Paul Airport on Monday evening.The incident happened as the DC-9 aircraft, with 66 passengers and four crew on board, was landing after a flight from Louisville, KentuckyNorthwest said that passengers were able leave the plane by stairs and initial reports indicated no injuries.Most of the passengers with onward connections from Minneapolis were able to continue their journeys on Monday evening flights.The airline says it is co-operating with federal authorities to investigate the causes of the incident which happened at 7.31 CDT. Leo/ORD