LED-32-11-SK-E0U4N – VIVISUN LED Cap and Body QQI MENU Switch
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Overview Section
The VIVISUN LED-32-11-SK-E0U4N is a highly specialized, aircraft-grade Switch Assembly designed for use as a primary interface in avionics control panels, typically serving as a Multi-Function Indicator (QQI) or MENU selection button. Manufactured by VIVISUN, a division of Oxley Group (formerly Interface Displays), this component is defined by its superior optical quality and rugged electro-mechanical performance necessary for the flight deck environment. The assembly integrates a tactile switch body with a precision-machined, removable LED cap, which provides the vital function of Mode Annunciation.
The switch’s critical feature is its lighting mechanism, which utilizes high-efficiency LED technology for reliability, long life, and precise color and luminance output. It is engineered to meet stringent requirements for Sunlight Readability (High Ambient Light) and Night Vision Goggle (NVG) Compatibility (MIL-STD-3009), ensuring the pilot receives unambiguous visual feedback regardless of ambient lighting conditions. Its robust, sealed construction guarantees reliable switching and illumination performance under shock, vibration, and temperature extremes as mandated by RTCA DO-160.
Key Features Section
Integrated LED Illumination: Uses high-efficiency Light Emitting Diodes (LEDs) within the cap for long life (Mean Time Between Failure greater than 100,000 hours) and minimal power consumption.
Sunlight Readability: Engineered for high luminance output and high contrast filtering to ensure clear legibility even in direct, high-ambient sunlight.
NVG Compatibility: Compliant with MIL-STD-3009 to ensure the emitted light spectrum does not interfere with Generation III Night Vision Goggles.
Tactile Feedback: Provides a positive, reliable tactile "click" to confirm mechanical actuation, a critical ergonomic feature for pilot workload management.
Front Panel Relampable: The LED cap assembly is removable from the front of the panel, allowing certified technicians to replace the light source without removing the entire switch body.
Sealed Construction: The switch body and cap assembly are environmentally sealed against dust, moisture, and common aviation fluids.
Specific Designation: The -E0U4N suffix defines the exact switch configuration (e.g., E0: Gold Contacts, U4: Specific Color/Filter, N: NVG Filter).
Technical Specifications Section
Part Number: LED-32-11-SK-E0U4N
Model Designation: LED Cap and Body QQI/MENU Switch
Component Type: Lighted Push-Button Switch / Annunciator
OEM Manufacturer: VIVISUN (Oxley Group)
Switch Mechanism: Push-Button, Momentary or Latching (Specific type defined by model code)
Contact Material: High-reliability material, typically Gold or Gold Alloy (E0 code)
Illumination Source: High-Intensity LED (Monochromatic or Bi-Color)
Voltage (Nominal): 28 VDC (Internal resistor network compensates for 28V use)
Switch Ratings: Low current, logic-level switching (e.g., 50 mA at 30 VDC Max)
Mounting: Panel Mount, typically requiring a rectangular or square bezel cutout.
Governing Specifications: Compliant with RTCA DO-160 (Environmental) and MIL-STD-3009 (Optical/NVG).
Aircraft Compatibility Section
Military Aircraft: Fighter, Transport, and Rotary-wing platforms requiring highly reliable, sunlight-readable, and NVG-compatible cockpit controls.
Special Mission/ISR: Aircraft equipped with integrated glass cockpits and mission systems that require customizable, high-integrity human-machine interfaces (HMI).
Commercial Transport: Modern airliners and business jets utilizing specialized annunciator panels and Mode Control Panels (MCPs).
Note: The switch configuration (momentary vs. latching, contacts) is determined by the specific aircraft system function (e.g., QQI vs. MENU). The aircraft's Wiring Diagram Manual is the final authority for verifying part number and electrical interface.
Applications Section
Flight Mode Annunciation (QQI): Used in Mode Control Panels (MCP) to select and annunciate Flight Director modes (e.g., HOLD, APPROACH, VNAV).
Control Display Unit (CDU) Input: Used as dedicated function keys (MENU, INDEX, CLEAR) for Flight Management System (FMS) control.
System Status Acknowledge: Providing a lighted button for accepting or clearing caution/warning messages.
Why Choose the LED-32-11-SK-E0U4N?
The VIVISUN LED-32-11-SK-E0U4N is a certified solution to a critical pilot safety challenge: ambiguous annunciation. Using non-certified or non-VIVISUN switches compromises the highly engineered balance between light output for daytime viewing and precise spectral filtering for NVG compatibility. A failure in this balance can lead to unreadable annunciations during the day or NVG 'blooming' or saturation at night, temporarily blinding the pilot. This switch's MIL-STD-3009 compliance guarantees that the pilot's visual perception of critical mode status is accurate and immediate under all conditions, a non-negotiable requirement for reducing spatial disorientation and improving crew resource management.
The optical performance of this VIVISUN switch is achieved through a multi-layer dichroic filter stack laminated directly into the switch cap. This stack is necessary to manage the spectral output of the high-intensity LED. For sunlight readability, the front surface incorporates an anti-reflection coating and a high-efficiency contrast filter. For NVG compatibility, the critical function is the attenuation of all light energy above 650 nanometers (the visible red light) to a level below the specified radiance limit (e.g., one point zero times ten to the power of minus ten Lambert) set by MIL-STD-3009. The gold contact system (E0 code) ensures extremely low and stable contact resistance, which is vital for logic-level switching applications where the avionics system relies on a clean, low-current discrete signal to sense the pilot's mode selection.
Note: The LED-32-11-SK-E0U4N is a flight-critical Human-Machine Interface (HMI) component. It is not a life-limited part, but the LED life is finite. Installation and wiring must be performed by a certified avionics technician. When replacing the cap, technicians must ensure the orientation and proper seating of the cap to maintain the switch’s environmental seal and optical integrity.
Documentation
VIVISUN/Oxley Interface Displays Product Data Sheet: Essential for specific wiring diagram, contact configuration, and luminance specifications.
MIL-STD-3009: Standard defining the optical characteristics for NVG compatible systems.
RTCA DO-160: Referenced Standard for Environmental Testing.
The technical difference between a momentary and a latching switch contact configuration is fundamental to the design and operation of any aircraft system interface. The choice between the two dictates how the pilot's input is handled by the Flight Control Computer (FCC) or the system controller.
Momentary Switch Configuration
Principle
A momentary switch only maintains its new electrical state (e.g., circuit closed or "ON") for the duration that the actuator (the push-button cap) is physically held down. Once the pilot's finger is removed, the contact immediately returns to its original state (e.g., circuit open or "OFF") via an internal spring or mechanism.
Avionics Application
Function: Used primarily for functions that require a brief, discrete "pulse" signal or a temporary condition.
Examples:
Autopilot Disconnect: Sending a brief signal to the FCC to disengage the autopilot.
Push-to-Talk (PTT): The circuit is only closed while the pilot speaks.
Annunciator Acknowledge/Reset: Sending a quick signal to clear a warning light (the warning system itself handles the logic, but the input is momentary).
Engineering Advantage
The momentary switch ensures that the pilot's input is not left permanently engaged inadvertently. The controlling avionics computer is programmed to look for the transition (the change of state from open to closed) rather than the continuous signal itself.
Latching (Alternate Action) Switch Configuration
Principle
A latching switch (also called an alternate action switch) changes its electrical state when pressed, and that new state is mechanically retained after the actuator is released. The contacts remain in the new position until the button is pressed a second time, which releases the internal mechanism and returns the contacts to the original state.
Avionics Application
Function: Used for functions that involve selecting a continuous mode or state that must be maintained until intentionally changed.
Examples:
Engine Anti-Ice: When the button is pushed, the anti-ice system is engaged and stays engaged until the button is pushed again to disengage it.
Fuel Pump Selection: Selecting an auxiliary or boost pump to remain running.
Panel Light Dimmer: Used in some rotary switches to select a specific dimming level that must be maintained.
Engineering Advantage
The latching switch provides a direct mechanical indication of the selected state, reinforcing the pilot's selection. In some simple systems, the contacts may directly control the power to the function, bypassing the need for complex control logic.
Summary Comparison
| Feature | Momentary Switch | Latching (Alternate Action) Switch |
| Contact State | Changes only while held down. | Changes when pressed, stays until pressed again. |
| Output | A brief pulse or transition signal. | A continuous ON or OFF status signal. |
| Typical Use | Disconnect, acknowledge, transmit (PTT). | Anti-Ice, Power Select, Mode Engage/Disengage. |
| Action | Push and Release = OFF | Push = ON; Push again = OFF. |