At approximately 1730 mountain time, a Grumman G-44 lost engine power and struck a house about a mile from Boise Air Terminal. The two pilots received serious injuries but the occupant in the residence was not injured. The pilot said the landing gear did not retract after takeoff and he pumped it up. The airplane then yawed and the engine rpm dropped on the right engine. He was returning to land but the airplane would not maintain altitude. Inspection of the right engine revealed a substantial amount of metal shavings in the fuel filter and bowl. Additional metal shavings were found in the right fuel tank.