3070800-36 - Honeywell Aerospace Turbine Engine Main Fuel Control Assembly

3070800-36 – Honeywell Aerospace Main Fuel Control (MFC) Assembly

Available now through the AirParts Aero marketplace.

Overview Section

The Honeywell 3070800-36 is a premium, high-precision Main Fuel Control (MFC) unit, also known as a Fuel Control Unit (FCU). Engineered for the Honeywell TFE731 turbofan engine series, the -36 dash number represents a highly evolved configuration of this hydro-mechanical "analog computer."

This assembly is the central intelligence for engine thrust management. It continuously calculates and delivers the exact fuel-to-air ratio by monitoring the pilot’s Power Lever Angle (PLA) alongside two critical environmental inputs: Compressor Discharge Pressure ($P_3$) and Inlet Temperature ($T_2$). The -36 variant is noted for its refined internal calibration, designed to provide the high degree of throttle linearity and surge protection required for modern business jet flight profiles.

Key Features Section

• Advanced Transient Response: Features optimized internal 3D cams that provide a crisp, predictable engine response during rapid throttle movements, essential for go-around maneuvers.

• Refined Surge Margin: Utilizing high-sensitivity pneumatic bellows, the -36 reacts instantaneously to changes in $P_3$ air density, effectively shielding the engine from compressor stalls and surges.

• Superior Governing Stability: Incorporates internal mechanical flyweight governors that maintain stable $N_2$ speeds, eliminating RPM "hunting" during high-altitude cruise.

• Low-Hysteresis Design: Engineered with ultra-smooth internal metering valves and low-friction coatings to ensure that power settings are repeatable and precise.

• Integrated Fail-Safe Protection: Includes a mechanical overspeed governor that acts as an ultimate shut-off to prevent the engine core from exceeding structural limits.

• Modern SB Compliance: As a late-series dash number, the -36 often incorporates the most recent Service Bulletin (SB) improvements regarding bellows longevity and drive-train vibration dampening.

Technical Specifications Section

Aircraft Compatibility Section

The 3070800-36 is a critical component for several of the world’s most advanced business jets powered by the TFE731 engine:

• Dassault Falcon 50EX / 900DX / 900LX: Found in the TFE731-40 and -60 engine variants for long-range global missions.

• Hawker 900XP: Essential for the fuel scheduling of the TFE731-50R engines.

• Learjet 40 / 45 / 45XR: Core component for the TFE731-20 series powerplants.

• Gulfstream G100 / G150: Utilized for precise thrust management and fuel efficiency.

Technical Applications & Safety

The MFC is a closed-loop feedback device. It ensures that for every molecule of air compressed by the engine ($P_3$), only the safe amount of fuel is added. If a sensing line leaks or an internal bellows fails, the MFC prevents the engine from over-fueling, which could result in an uncontained "hot section" failure.

** THIS ITEM WAS REPLACED BY HONEYWELL PART NUMBER: 3070800-46.

Safety Warning: FCU installation requires a mandatory "Part Power Trim" procedure. This ground-run calibration ensures the engine’s Interstage Turbine Temperature (ITT) is synced with the FCU's acceleration schedule. Failure to properly rig the 3070800-36 can lead to "Hot Starts" or over-temping during takeoff, leading to catastrophic turbine damage.

Technical Engineering Insight

The engineering value of the 3070800-36 lies in its Pneumatic-to-Mechanical Transduction Accuracy. By refining the bellows assembly, Honeywell reduced the "dead band" in throttle response. This means that even at the flight ceiling (FL510), where air density is minimal, the -36 provides the granular control needed for precision speed adjustments without the "lag" found in earlier generation controls.

By choosing a certified 3070800-36 through AirParts Aero, you are guaranteed a unit that has been bench-tested on a computer-controlled fuel stand to verify its Steady State and Transient Schedules match the Honeywell master engineering curve.

Installation & Maintenance Addendum

1. $P_3$ Sensing Line Inspection: Always verify the integrity of the $P_3$ line; any "carboning" or moisture in this line will cause the engine to "surge" or "stumble" during power changes.

2. Mounting Gasket: Always use a new OEM mounting gasket (typically a specialized O-ring or metal-clad seal) to prevent oil leaks from the Accessory Gearbox.

3. Shaft Lubrication: Apply the specified anti-seize lubricant to the drive splines to protect against "fretting," which can lead to a loss of drive input and subsequent engine flame-out.