Bulkhead Nut #4 Black

The FRAGOLA Bulkhead Nut #4 Black (part number 492404-BL) is a precision-engineered aluminum fitting nut designed for AN-4 bulkhead connections. This black anodized component serves as a critical interface in high-pressure fluid systems, securing bulkhead fittings to panel-mounted applications in aerospace, automotive, marine, and industrial hydraulic assemblies. The AN-4 size indicates a nominal 1/4-inch port, making it compatible with standard 1/4-inch AN bulkhead fittings across professional and performance applications.

Constructed from lightweight aluminum and finished with black anodize coating, this bulkhead nut provides corrosion resistance in salt-air and humid environments while maintaining minimal weight—critical in aerospace and marine contexts. The anodized finish also improves grip durability during installation and removal cycles. At 0.01 lbs with compact dimensions (1.25 x 1.05 x 4.1 inches), it integrates seamlessly into confined spaces without adding system weight. Proper torque specifications and compatible thread sealant ensure leak-free operation under rated pressure conditions.

This component is essential for anyone assembling or repairing AN-4 bulkhead connections in fuel systems, coolant lines, brake circuits, or hydraulic manifolds. Whether you're a restoration specialist rebuilding aircraft, a marine technician servicing offshore equipment, or an automotive engineer developing custom fluid routing, AN-4 bulkhead nuts are non-negotiable consumables. The black anodize variant offers superior aesthetics in visible installations while delivering the same functional reliability as standard finishes. FRAGOLA is a recognized manufacturer of aircraft and automotive fluid fittings, ensuring engineering consistency across bulkhead fitting systems.