Aviation helmet

An adjustment mechanism comprising:

• a housing including a sidewall extending circumferentially around a central axis, the sidewall defining an opening extending along the central axis and including a first aperture extending through the sidewall in a direction perpendicular to the central axis;
• a receiving member coupled to the housing and rotatable about the central axis, the receiving member including a protrusion extending along the central axis, the protrusion including an aperture extending along an axis spaced from and parallel to the central axis;
• a cable having a first end and a second end, the first end extending through the first aperture in the housing and the aperture in the receiving member and fixedly coupled to the receiving member, the second end fixed relative to the housing;
• a knob coupled to the housing and rotatable about the central axis, the knob including a first protrusion configured to engage the protrusion of the receiving member such that rotation of the knob causes the receiving member to rotate;
• a locking element engaged with an interior surface of the sidewall of the housing, the locking element configured to be disengaged with the interior surface of the sidewall in response to a manual rotation of the knob by a user;
• a base configured to receive at least one compressible comfort pad, the base comprised of a rigid material and having an outer surface, an inner surface and a protrusion extending outwardly from the outer surface, the outer surface being generally convex and the inner surface being generally concave, the protrusion defining an first aperture disposed on a first side of the protrusion and a second aperture disposed on a second side of the protrusion opposite the first side;
• and
• a strap extending through the first aperture and the second aperture in the base, the strap configured to receive a fastener at a first end of the strap such that a position of the strap is fixed relative to the adjustment mechanism, the first strap having a second end opposite the first end, the second end looped around the cable of the adjustment mechanism,
• wherein the base includes a flexible arm configured to couple the base to a helmet shell, wherein rotation of the knob causes the base to be displaced relative to the housing and causes the flexible arm to be elastically deformed.

An aviation helmet comprising:

• a helmet shell having an outer surface and an inner surface;
• and
• a base configured to be positioned proximate a nape of a user's neck when the user wears the helmet shell, the base adjustably coupled to the helmet shell by an adjustment mechanism, the adjustment mechanism comprising:
• a housing fixedly coupled to the helmet shell and including a sidewall extending circumferentially around a central axis, the sidewall defining an opening extending along the central axis and including a first aperture extending through the sidewall in a direction perpendicular to the central axis;
• a receiving member coupled to the housing and rotatable about the central axis, the receiving member including a protrusion extending along the central axis, the protrusion including an aperture extending along an axis spaced from and parallel to the central axis;
• a cable coupled to the base and having a first end and a second end, the first end extending through the first aperture in the housing and the aperture in the receiving member and fixedly coupled to the receiving member, the second end fixedly coupled to the helmet shell;
• a knob coupled to the housing and rotatable about the central axis, the knob including a first protrusion configured to engage the protrusion of the receiving member such that rotation of the knob causes the receiving member to rotate;
• and
• a locking element engaged with an interior surface of the sidewall of the housing, the locking element configured to be disengaged with the interior surface of the sidewall in response to a manual rotation of the knob by a user.