Protective Helmet

FIG. 1 is a front perspective view of a protective helmet showing my new design; FIG. 2 is a rear perspective view thereof; FIG. 3 is a front view thereof; FIG. 4 is a left side view thereof; FIG. 5 is a right side view thereof; FIG. 6 is a rear view thereof; and, FIG. 7 is a top view thereof. The broken lines represent portions of the protective helmet that form no part of the claimed design.