Northwest Super Constellation N6214C departed Seattle-Tacoma at 01:48 for a flight to Chicago. Shortly after takeoff the no. 3 prop oversped. The prop was feathered, but continued to rotate at 400rpm. While climbing through 5000 feet a severe loss of oil forced the crew to feather the no. 4 prop as well. It was decided to carry out an emergency landing at McChord AFB. Only the right hand main gear leg could be locked down prior to landing. This caused the plane to swerve off the runway, bursting into flames. All occupants were evacuated in time. PROBABLE CAUSE: “A sequence of mechanical failures resulting in an emergency landing under adverse weather conditions with insufficient hydraulic pressure in the secondary system to extend fully the landing gear in the time available. A contributing factor was the design of the hydraulic system which did not permit use of the available pressure in the primary system for that purpose.”