D38999 Bulkhead Connectors

MIL-DTL-38999 Series Bulkhead Connectors: High-Reliability Feed-Through Interconnect Solutions

Product Overview

Our MIL-DTL-38999 Series III Type Bulkhead Connectors—also widely recognized as Bulkhead Feed-Through Adapters, Chassis Connectors, or Panel Pass-Throughs—seamlessly facilitate secure data and power transmission through sealed enclosures, aircraft bulkheads, and pressure hull barriers.

Built strictly to comply with the mechanical envelope of the MIL-DTL-38999 Series III standard, these circular components provide a reliable plug-to-plug connection on both sides of a panel cutout. This allows robust connectivity without compromising environmental sealing or electromagnetic protection.

When electrical cables or fiber optic lines must pass from a harsh external environment into a protected electronic system, D38999 bulkhead connectors provide a rugged and reliable feed-through interface. This eliminates risks associated with exposed wiring and helps maintain stable signal integrity.

Detailed Mating Configurations & Interface Logic

To simplify system integration, these bulkhead feed-through connectors are designed with symmetrical construction and clear polarization. Unlike standard receptacles, each bulkhead adapter includes two mating faces: front (external side) and rear (internal side).

Pin/Socket Gender Configurations

We offer three standard interface types:

Pin-to-Pin:
Male contacts on both sides, typically used when both cable assemblies use socket connectors.

Pin-to-Socket:
Male contacts on the front side and female contacts on the rear side, enabling direct in-line extension without cable redesign.

Socket-to-Socket:
Female contacts on both sides, compatible with standard pin-type cable plugs.

Keyway Polarization Stability

Each bulkhead connector uses a master key and multiple keyway positions (N, A, B, C, D, E). The keying system is mechanically continuous through the connector body, ensuring front and rear alignment consistency.

This design prevents incorrect mating and avoids rotational misalignment that could damage contacts or fiber end faces.

Technical Mechanics of Bulkhead Feed-Throughs

Unlike standard receptacles, bulkhead connectors function as a true plug-to-plug feed-through interface.

• Bi-directional mating accepts standard D38999/26 straight plugs on both sides
• Solid contact structure ensures precise alignment across the panel barrier
• Extended thread design supports varying panel thicknesses, from thin avionics housings to heavy industrial enclosures

Key Performance Features

• Fast mating using triple-start threaded coupling (approximately 1.5 turns full engagement)
• Recessed contact design protects pins and fiber termini during blind mating
• Zirconia ceramic ferrules provide low insertion loss performance (typically ≤0.5 dB depending on configuration)
• 360° metal shell contact ensures EMI shielding continuity
• Fluorosilicone seals provide protection against moisture, dust, and fluid ingress
• Available in aluminum alloy or stainless steel shells for different environments
• Corrosion-resistant finishes include zinc-nickel and electroless nickel plating
• Supports multi-channel signal configurations based on shell size and insert arrangement
• Hybrid configurations allow fiber, power, and coax contacts within one connector

Technical Specifications & Parameters

Mechanical & Environmental

• Operating temperature: -65°C to +125°C (aluminum), up to +200°C (stainless steel)
• Environmental sealing: IP67/IP68 rated depending on configuration and mating condition
• Hermetic versions: leak rate ≤ 1 x 10^-7 atm·cm³/s under 1 bar differential pressure
• Vibration resistance: up to 60g under MIL-STD test conditions

Materials & Finishes

• Aluminum alloy shells for lightweight aerospace applications
• Stainless steel shells for high-corrosion marine and subsea environments
• Black zinc nickel and electroless nickel finishes for corrosion resistance and conductivity

Advanced Insert Arrangements

Supports high-current contacts (size 8, 12, 16) and high-density signal contacts (size 20, 22D).

Fiber Optic & Hybrid Configurations

Supports MIL-PRF-29504 fiber optic termini as well as coaxial, twinax, and quadrax contacts. Hybrid configurations enable combined optical and electrical transmission within a single connector system.

Structural Reliability Features

• Anti-galling surface treatment for stainless steel threads
• Contact retention system prevents terminal push-out under mating stress
• Dual-groove sealing design maintains compression under thermal cycling

Typical Applications

• Aerospace and avionics enclosure feed-through systems
• Subsea and marine pressure-rated electronic housings
• Tactical military shelters and communication vehicles
• Industrial vacuum and sealed control systems

Intermateability & Quality Assurance

These connectors are manufactured to standard MIL-DTL-38999 dimensional specifications, ensuring mechanical compatibility with standard D38999 Series III plugs.

All units are inspected under AS9100D and ISO 9001 quality systems, with full traceability for aerospace and defense procurement requirements.