Details
39A2450 is the North American Aviation drawing number for a Dzus Type SB spring, alternate part number SB4-1, for use with size 4 (1/4 inch body diameter) Dzus fasteners. Type SB and Type SC springs are the box corner and box side styles, and the period Dzus catalog notes that Type SC and SB springs may be used with Type AW and Type F fasteners. They mount to the side or corner of a box or structure where a standard flat S spring cannot be riveted.
ABOUT: Dzus fasteners are quarter-turn, self-locking panel fasteners made of heat-treated, cadmium plated nickel steel, used with an aluminum grommet and a music wire spring. The stud passes through the removable panel, the grommet locates and protects the panel hole, and the spring is riveted to the underlying structure where it takes the load and provides the locking action. They are used on covers, plates, cowlings, and similar panels that require quick removal and replacement. Worn, bent, or broken parts must be replaced to maintain clamp load and vibration resistance.
Part Number: 39A2450
Alt Part Number: SB4-1
Part Type: Spring, Dzus, Type SB box side
Mfg: Dzus Fastener Co., Inc.
Size Family: 4 (for 1/4" body diameter studs)
Used With: Type A, AJ, AW, F, and FJ size 4 studs
Aircraft: North American Aviation types and others
Condition: NS, shelf wear due to age
DETAILS: Dzus spring designations use S for a standard spring, followed by the size number of the stud it serves and a dash number giving spring height. The SB prefix marks the box side variant rather than the flat standard spring, so the dash number on an SB spring is a configuration number rather than a height in thousandths. Size 4 springs are normally riveted with 3/32 inch rivets.
For a full breakdown of Dzus type codes, size families, and how to select a stud, grommet, and spring together, see our blog post About Dzus Fasteners.
Images for reference only.
Warranty Information
