The helicopter collided with the snow-covered ground after the engine quit during a power-line patrol at about 30 ft AGL. The pilot reported that the visibility was 1/2 mile with light snow falling. He also said he could see 4 to 7 of the supporting structures. These poles are spaced about 350 ft apart so seven poles total less than 1/2 mile. The Bell 206BFLT manual states that 'operations are permitted in falling snow when visibility is in excess of 1/2 mile, but flight duration is limited to 1 and 1/2 hours.' Investigation of the engine after the accident revealed that when the top plug of the fuel pump filter was loosened, the sound of escaping air was noted. Investigation also revealed that on the day of the accident the forward fuel boost pump had been replaced with a new IC-38-L type pump which had been signed off as having been checked for pressure and bled.