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100-389018-23 – Textron Aviation OEM Fuel Pressure Switch
Available now through the AirParts Aero marketplace.
Overview Section
The 100-389018-23 is an authentic Textron Aviation OEM (Original Equipment Manufacturer) fuel pressure switch. This precision-calibrated safety component is a critical part of the fuel management and cockpit annunciation system, primarily used in the Beechcraft King Air and 99 Series aircraft.
The switch is designed to monitor the fuel pressure delivered by the engine-driven fuel pump or the boost pump. If the pressure drops below a specific, pre-set threshold, the switch closes (or opens) an electrical circuit, triggering a "FUEL PRESS" warning light on the pilot's annunciator panel. This immediate alert allows the flight crew to activate standby pumps or troubleshoot a potential engine flameout condition.
Key Features Section
OEM Reliability: Manufactured to the exact specifications required by the aircraft's Type Certificate, ensuring seamless integration with the existing wiring harness and fuel lines.
Precision Calibration: Factory-set to trigger at a specific PSI, providing accurate and repeatable warnings throughout the life of the component.
Environmental Sealing: The electrical housing is ruggedized and sealed to withstand the vibration, moisture, and temperature extremes found in an aircraft's engine nacelle.
Corrosion-Resistant Ports: Features high-grade metallic fluid ports designed to resist degradation from constant exposure to Jet A and JP-8 fuels.
Gold-Plated Contacts: Often utilizes specialized electrical contacts to ensure a reliable connection even after long periods of inactivity in a high-vibration environment.
Direct Replacement: Designed as a "plug-and-play" component for the 100-389018 series, requiring no modification to the mounting bracket or electrical connectors.
Technical Specifications Section
| Specification | Detail |
| Part Number | 100-389018-23 |
| Manufacturer | Textron Aviation (Beechcraft) |
| Component Type | Diaphragm-Actuated Pressure Switch |
| Fluid Compatibility | Jet Fuel (Jet A, Jet A-1, JP-8) |
| Connector Type | Standard Aviation Screw Terminal or Circular Connector |
| Pressure Port | Standard Threaded Fitting (refer to IPC for dash size) |
| Certification | FAA-PMA / OEM |
Aircraft Compatibility Section
The 100-389018-23 is a vital part of the safety systems in the following Textron Aviation models:
Beechcraft King Air 90 Series: C90, E90, F90.
Beechcraft King Air 200 Series: B200, B200GT.
Beechcraft King Air 300/350 Series: 300, B300.
Beechcraft 99 Airliner: Used across various configurations of the commuter turboprop.
Technical Applications & Safety
In a turbine aircraft like the King Air, fuel pressure is vital for the operation of the High-Pressure Fuel Pump. A "Low Fuel Pressure" indication is a Redline/Warning event.
Safety Warning: Installation and Testing. When installing the 100-389018-23, ensure the fuel system is depressurized. After installation, a leak check is mandatory while the boost pumps are active. Additionally, the switch's functionality should be verified during the aircraft's scheduled Phase Inspections by using a calibrated pressure source to ensure the annunciator light triggers at the exact PSI specified in the Aircraft Maintenance Manual (AMM). Never attempt to "re-calibrate" an OEM switch in the field; if the trip point is incorrect, the unit must be replaced.
Installation & Maintenance Addendum
Thread Sealant: Use only aviation-approved fuel-resistant thread lubricant (such as EZ-Turn) on the pressure port threads. Do not use Teflon tape, as shreds can enter the fuel system and clog the switch diaphragm or engine fuel nozzles.
Electrical Continuity: Before flight, perform a "Press-to-Test" on the annunciator panel to ensure the bulb is functional, then verify the light extinguishes once the engine-driven pump reaches operating pressure.
Vibration Dampening: Ensure the mounting bracket is secure. Excessive vibration can cause "chatter" in the electrical contacts, leading to intermittent or false "Low Fuel Press" warnings.
Applicable Textron Aircraft
- King Air 350 Fusion
- King Air 350C FM-36 & On
- King Air 350C Fusion
- King Air 350i
- King Air 360
- King Air 360C
- King Air B200, B200T, B200C or B200CT
- King Air B200GT
- King Air B200GT Fusion or B200CGT Fusion
- King Air C90, C90A, C90GT or E90
- King Air C90GTi
- King Air C90GTx
- King Air C90GTx Fusion
- Super King Air 350
- Super King Air 350C FM-1 to FM-35
List not comprehensive, may be applicable on other models.
