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3070800-54 – Honeywell Aerospace Main Fuel Control (MFC) Assembly
Available now through the AirParts Aero marketplace.
Overview Section
The Honeywell 3070800-54 is a high-precision Main Fuel Control (MFC) unit, also categorized as a Fuel Control Unit (FCU). Engineered for the Honeywell TFE731 turbofan engine series, the -54 dash number represents a specialized, late-generation configuration. It is a hydro-mechanical "analog computer" designed to provide peak fuel metering accuracy for the high-thrust variants of the TFE731 family.
This assembly acts as the central command for engine combustion. It monitors pilot input via the Power Lever Angle (PLA) and cross-references it with critical environmental sensors: Compressor Discharge Pressure ($P_3$) and Inlet Temperature ($T_2$). The -54 variant is specifically calibrated to handle the increased airflow and thermal requirements of modern turbofan operations, ensuring smooth power transients and stable governing at all altitudes.
Key Features Section
Advanced Hydro-Mechanical Logic: Utilizes a complex internal system of bellows and 3D cams to calculate the optimal fuel flow for any given flight condition.
Optimized for High-Altitude Cruise: Features refined pneumatic sensing technology to ensure stable engine speeds ($N_2$) and prevent RPM "hunting" in thin air.
Precision Acceleration Schedules: Engineered to provide rapid, linear throttle response while maintaining a maximum safety margin against compressor surges.
Hardened Internal Metering Valves: Incorporates advanced surface treatments to resist "stiction" and wear caused by diverse fuel types or microscopic contaminants.
Integrated Mechanical Governor: Provides a fail-safe $N_2$ overspeed protection, physically limiting fuel flow to protect the engine core from structural damage.
Ruggedized Cast Housing: Constructed from a high-integrity aluminum alloy designed to dissipate heat and withstand the intense vibrations of the Accessory Gearbox (AGB) mounting.
Technical Specifications Section
| Specification | Detail |
| Part Number | 3070800-54 |
| Manufacturer | Honeywell Aerospace |
| Engine Application | TFE731-40, -50, and -60 Series variants |
| Input Signals | Power Lever Angle (PLA), $P_3$ (Pneumatic), $T_2$ (Temperature) |
| Fuel Compatibility | Jet-A, Jet-A1, JP-5, JP-8 |
| Control Logic | Hydro-mechanical with Pneumatic Override |
| Weight | Approximately 18.7 lbs |
Aircraft Compatibility Section
The 3070800-54 is a critical component for high-performance business jets utilizing the TFE731 geared turbofan:
Dassault Falcon 900EX / 900LX: Essential for the fuel management of the TFE731-60 series turbofans.
Hawker 900XP: Found in the high-efficiency TFE731-50R engine configurations.
Gulfstream G150: Core component for the TFE731-40AR powerplants, providing reliable transcontinental performance.
Dassault Falcon 50EX: Utilized in the upgraded -40 series engine installations for enhanced climb performance.
Technical Applications & Safety
The MFC operates as a closed-loop feedback system. It continuously monitors the "work" the engine is doing via the $P_3$ signal. If the $P_3$ sensing line is restricted by carbon or moisture, the 3070800-54 will sense an artificial "low air" condition and limit fuel flow, which can prevent the engine from reaching takeoff power.
Safety Warning: FCU installation requires a mandatory "Part Power Trim" procedure. This is a safety-of-flight task performed on the ground to synchronize the MFC with the engine's Interstage Turbine Temperature (ITT). Failure to correctly rig the 3070800-54 can result in "Hot Starts" or over-temperature events that can cause permanent, multi-million dollar damage to the turbine's hot section.
Technical Engineering Insight
The engineering value of the 3070800-54 lies in its Pneumatic Signal Dampening. In high-pressure engines, the $P_3$ air can be highly turbulent. The -54 variant uses precision-drilled orifices to dampen these pressure "pulses" before they reach the sensing bellows. This ensures a rock-steady power setting even in turbulent flight conditions, which is vital for the accuracy of modern autothrottle systems.
By choosing a certified 3070800-54 through AirParts Aero, you ensure the unit has been bench-tested on a computer-controlled fuel stand to verify its Acceleration and Deceleration Schedules match the Honeywell master engineering curve.
Installation & Maintenance Addendum
$P_3$ Filter Replacement: Always install a new $P_3$ air filter when replacing the MFC. A clogged filter is the most common cause of "sluggish" engine response.
Drive Spline Integrity: Inspect the drive splines on the accessory gearbox for "red dust" (fretting). Apply the specified high-pressure lubricant to the 3070800-54 drive shaft to ensure longevity.
Preservation: If the unit is removed and stored, it must be filled with MIL-PRF-6081 preservation oil. If left dry, the internal steel bellows can corrode, causing the unit to fall out of calibration.
| Specifications | |
|---|---|
| Cage Code | 99193 |
