United A319 at Portland on Jun 3rd 2014, could not retract landing gear

A United Airbus A319-100, registration N835UA performing flight UA-470 from Portland,OR to Houston Intercontinental,TX (USA), was in the initial climb when the crew stopped the climb at 4000 feet reporting they could not retract the landing gear. The aircraft returned to Portland for a safe landing about 20 minutes after departure.

The problem was fixed, the aircraft departed again after 2.5 hours on the ground and reached Houston with a delay of 3:10 hours.