501-1112-01 - Bombardier Learjet OEM Actuator

501-1112-01 – Bombardier Learjet OEM Linear Actuator

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The Bombardier Learjet 501-1112-01 is a high-precision, flight-critical electromechanical linear actuator designed for secondary flight control or utility system modulation. Specifically engineered for the Learjet 45 and 60 series, this actuator translates rotational torque from an internal DC motor into precise linear displacement. It is primarily utilized in systems requiring robust, repeatable positioning under aerodynamic load, such as trim tab adjustment, flap/slat secondary drives, or environmental control system (ECS) valve modulation.

As an OEM component, the 501-1112-01 is manufactured to survive the harsh environmental envelope of business aviation, including rapid pressure changes, extreme thermal cycling, and high-frequency airframe vibration. It features an integrated gearbox for high-torque output and a feedback mechanism (typically a potentiometer or LVDT) that provides the aircraft’s flight control computer or avionics suite with real-time positional data. For the maintenance professional, this actuator represents a reliable, certified solution that ensures the aerodynamic and mechanical systems of the Learjet remain within their original design parameters.

Key Features

• Electromechanical Precision: Utilizes a 28V DC brushed or brushless motor coupled with a precision ballscrew or acme screw for smooth, accurate linear movement.

• Integrated Feedback Loop: Equipped with internal sensors to ensure precise closed-loop control, allowing the cockpit flight deck to monitor exact travel positions.

• High Force-to-Weight Ratio: Engineered with aerospace-grade alloys to provide maximum mechanical thrust while minimizing the impact on the aircraft’s center of gravity.

• Fail-Safe Mechanical Stops: Features internal limit switches and mechanical hard-stops to prevent over-extension and protect the airframe structure from unintended damage.

• Environmental Sealing: Hermetically or environmentally sealed to prevent the ingress of moisture, hydraulic fluids, and dust, ensuring long-term reliability in unpressurized bays.

Technical Specifications

• Part Number: 501-1112-01

• Manufacturer: Bombardier Learjet (OEM Supplier: often Rosemount or Honeywell)

• Component Type: Electromechanical Linear Actuator

• Operating Voltage: 28 VDC (Nominal)

• Current Draw: (Refer to CMM; typically varies based on load)

• Stroke Length: Precision-calibrated for specific Learjet airframe station

• Mounting Type: Clevis-to-Clevis or Trunnion mount

• Feedback Signal: Resistance (Ohms) or Voltage (VDC) proportional to stroke

• Governing Specifications: RTCA DO-160

• Certification: FAA-PMA / Bombardier OEM Original Equipment

Aircraft Compatibility

• Learjet 45 / 45XR

• Learjet 60 / 60XR

• Note: This specific dash number is often associated with the Elevator Trim or specific ECS modulating valves. Always verify the effectivity and serial number in the Learjet Illustrated Parts Catalog (IPC).

Applications

• Elevator Trim Tab: Providing precise longitudinal pitch trim for pilot relief and autopilot interface.

• Aileron Trim: Correcting for lateral imbalances during various phases of flight.

• ECS Modulating Valve: Controlling the flow of hot bleed air for cabin temperature regulation.

Why Choose 501-1112-01?

Choosing the OEM 501-1112-01 ensures that the actuator’s Duty Cycle and Static Load Capacity are perfectly matched to the Learjet’s flight envelope. Aftermarket or non-certified alternatives may suffer from "Back-Drive" issues, where the aerodynamic load forces the actuator to move out of position when unpowered. The 501-1112-01 utilizes an internal Electromagnetic Brake or a high-friction screw pitch to ensure that the set position is maintained regardless of external pressure. This reliability is critical for maintaining the aircraft's stability and ensuring passenger comfort.

The 501-1112-01 operates on the principle of Kinematic Power Conversion. The motor’s high-speed, low-torque rotation is converted through a Planetary Gear Reduction system into high-torque rotation, which then drives a Ballscrew. The ballscrew is a high-efficiency mechanism that utilizes recirculating ball bearings to minimize friction, allowing for near-instantaneous response times to pilot inputs.

From a control systems perspective, the actuator is a Servo-Mechanism. The internal feedback potentiometer creates a voltage divider circuit. As the actuator extends, the resistance changes; the Flight Control Computer (FCC) compares this "actual" voltage to the "commanded" voltage from the cockpit. Any discrepancy results in a correction signal sent to the motor. This ensures that the trim or valve position is accurate within thousandths of an inch, preventing "hunting" or oscillation in the aircraft’s control surfaces.

Note: The 501-1112-01 is a flight-critical component. Any evidence of "flat spots" in the potentiometer, grinding noises during operation, or excessive play in the rod-end bearings is cause for immediate removal and overhaul. Installation requires precise rigging and travel-limit verification as per the Learjet Aircraft Maintenance Manual (AMM) Chapter 27 or 21. Installation must be performed by a certified A&P mechanic.

Documentation

• No public-facing OEM technical data sheet was located for this specific part number. Please refer to the Bombardier Learjet AMM or the Component Maintenance Manual (CMM) for detailed wiring pin-outs and rigging procedures.