MIL-DTL-38999 Hermetic Connectors: Procurement Guide for Flight-Critical Programs
MIL-DTL-38999 defines the most widely deployed circular connector family in modern aerospace and defense. The spec governs miniature, scoop-proof, environment-resistant circular connectors with three active series in production .
Series Overview:
Series | Coupling | Best For |
|---|---|---|
Series I | Bayonet | Legacy airframes, ground equipment, vibration-prone installations |
Series II | Low-silhouette bayonet | Weight- and space-constrained installations |
Series III | Triple-start threaded | New aerospace programs (dominant choice) |
Hermetic Connectors:
Hermetic 38999 connectors use glass-to-metal seals (rather than elastomeric) to seal against pressure differential. Required for avionics bays, cryogenic systems, hazardous-location equipment, and fuel-system bulkheads.
Key Procurement Questions:
Is the exact part number on the current QPL (Qualified Products List)?
When was the most recent re-qualification?
Is the supplier the original QPL holder or distributing a third party's product?
Shell plating options include olive drab cadmium (being phased out), electroless nickel, stainless passivated, and zinc-cobalt.
