bulkhead

A bulkhead is a physical barrier, typically a flat panel of metal or composite material, that separates equipment, chambers, or compartments. Connectors, cables, fluid lines, or electrical contacts pass through openings in this barrier, and a bulkhead connector is specifically designed to mount flush against the bulkhead surface, allowing the connection to occur across the divide without requiring the mating connector to protrude into the space on either side.

In practice, bulkheads are load-bearing walls in pressure vessels, aircraft fuselages, and spacecraft hulls, or simple sheet-metal partitions in cabinets and enclosures. They serve structural, thermal, or operational purposes. A bulkhead connector has threads or a panel-mount flange that secures it perpendicular to the bulkhead face; the cable or mating connector then attaches to the back of the bulkhead. This arrangement saves space and keeps the compartment behind the bulkhead uncluttered.

Common bulkhead connector types include RF coaxial connectors (SMA, N-type, Type-F), circular mil-spec connectors, and fiber-optic feedthroughs. Each variant has a threaded or bayonet back end that locks the connector to the bulkhead from one side, while the signal passes through to the other side. The bulkhead itself absorbs the mechanical stress of mating and unmating, rather than the cable or internal equipment.

Where the name comes from

The term originates in naval architecture, where a bulkhead is any vertical wall that divides a ship's interior, improving structural integrity and containing flooding to one compartment. The term transferred to aerospace and industrial electrical terminology because the function is identical: a barrier that compartmentalizes space and provides a mounting point for pass-throughs.

Bulkhead connectors are essential in applications where reliability and space efficiency matter: aircraft avionics bays, missile guidance systems, laboratory equipment racks, and sealed chambers. They prevent accidental damage to mating connectors during cable routing, reduce the force exerted on internal equipment during connection, and simplify panel layout. Incorrect bulkhead mounting or a damaged bulkhead face can cause signal loss, mechanical looseness, or environmental seal failure.