An earplug connector for simultaneously providing an audio signal from a vehicle or an extra-vehicular source to a pilot while providing power to a noise reduction device while operating the vehicle. The earplug connector has a multi-pin connector for receiving audio signal and power from a pilot interface assembly connected to the vehicle. A ground, power, and audio signal connector transfers power to a noise reduction device worn by a pilot. An audio output continuously transfers audio signals from the multi-pin connector to earplugs and a multi-pin signal separator is in electrical and audio communication between the multi-pin connector and the ground, power, and audio signal connector. The audio output receives audio signals from the multi-pin connector and selectively passes the audio signals to the earplugs while transferring power to a noise reduction device while accepting a plurality of pin configurations.

An adjustment mechanism is disclosed that includes a housing that has a sidewall extending circumferentially around a central axis defining an opening. A first aperture extends through the sidewall perpendicular to the central axis and a receiving member rotatably coupled to the housing and includes a protrusion that extends along the central axis and an aperture spaced from the central axis. A cable has a first end that extends through the first aperture of the housing and is fixedly coupled to the receiving member and a second end fixed relative to the housing. A knob is rotatably coupled to the housing and is configured to engage the receiving member such that rotation of the knob causes the receiving member to rotate. A locking element engages with the sidewall of the housing, and is configured to disengage the sidewall in response to a manual rotation of the knob by a user.

A visor assembly for a helmet includes a helmet cover configured to couple to a helmet, a visor pivotably coupled to the helmet cover and configured to selectively pivot between a stowage position and one or more usage positions relative to the helmet cover, and a latching mechanism coupled to the visor. The latching mechanism includes a first pawl configured to rotate between a locked position and an unlocked position. The latching mechanism is further configured to releasably lock the visor in one or more of the stowage position and the one or more usage positions.

A helmet includes one or more vacuum retention systems lining and affixed to an interior of the helmet. The vacuum retention systems are containers including a plurality of microbeads and a valve allowing air to be added into or subtracted from the containers, compactifying the microbeads around the head of a pilot. The vacuum retention systems are connected to inflatable bladders in a suit of the pilot, thereby allowing air evacuated from the vacuum retention systems to be used to inflate the bladders. The vacuum retention systems are able to be connected to one or more sensors of a plane and the rigidity of the vacuum retention systems is able to be automatically adjusted based on sensor readings (e.g., G-force measurements).