S2041-50B1.6 – Textron Aviation Ignition System Ballast Resistor
Available now on the Airparts.aero Marketplace.
The S2041-50B1.6 is a genuine Textron Aviation (Cessna) OEM, flight-critical power resistor. This is not a common electronics component; it is an engineered ballast resistor designed for a specific and essential role in the engine ignition systems of many Cessna aircraft. Its primary function is to regulate the voltage and current supplied to the ignition coil(s). It protects the coil from overheating during normal engine operation, while a bypass circuit allows for a boosted, high-energy spark during engine start.
This component is a high-power, wirewound resistor, precision-manufactured to have a specific resistance of 1.6 Ohms. It is constructed by winding a nickel-chromium alloy (Nichrome) wire around a ceramic core and encasing the assembly in a heat-dissipating ceramic body. The reliability of the entire ignition system is dependent on this resistor's ability to maintain its specified resistance under high temperatures and continuous electrical load. A failure of this component will result in a total loss of engine ignition.
Key Features
Genuine Textron Aviation OEM Part: Guarantees the precise resistance value, power rating, and material specifications required for the certified ignition system.
Functions as an Ignition Ballast Resistor: Limits current to the ignition coil during normal operation to prevent overheating, and is bypassed during start-up to provide a hotter spark.
Wirewound Construction for Durability: Engineered to withstand the high temperatures and vibration of the engine compartment, providing a long and reliable service life.
Provides a "Boost" for Engine Starting: The bypass system associated with this resistor ensures maximum available voltage reaches the ignition coil during engine cranking for faster, more reliable starts.
Critical for Ignition System Reliability: A properly functioning ballast resistor is essential for the long-term health of the ignition coils and consistent spark performance.
Technical Specifications
Part Number: S2041-50B1.6
Component Type: Ballast Resistor, Wirewound Power Resistor
OEM Manufacturer: Textron Aviation (Cessna)
Resistance: 1.6 Ohms (Ω).
Power Rating: Rated for the high power dissipation required by a continuous-duty ignition circuit (consult maintenance manual for specific wattage).
Construction: Nickel-Chromium (Nichrome) resistance wire wound on a ceramic core, with a protective ceramic body.
Aircraft Compatibility
The S2041-50B1.6 is the specified ignition ballast resistor for a wide range of Textron Aviation (Cessna) aircraft, particularly those with specific ignition system configurations (e.g., non-impulse coupled or "shower-of-sparks" starting systems). Common applicable models include, but are not limited to:
Cessna 150, 152
Cessna 172 Skyhawk
Cessna 177 Cardinal
Cessna 182 Skylane
Crucial Note: The specific aircraft model and serial number must be checked against the latest revision of the official Textron Aviation (Cessna) Illustrated Parts Catalog (IPC) and Wiring Diagram Manual to ensure correct part number applicability.
Applications
Located in the firewall-forward engine compartment, wired in series with the primary circuit of the ignition coil(s).
Replacement part for a failed (open circuit) or out-of-tolerance resistor, which typically manifests as a "cranks but won't run" condition.
Why Choose S2041-50B1.6?
Choosing the genuine Textron S2041-50B1.6 is a critical decision for the reliability of your ignition system. The resistance and power rating of this component are precisely matched to the electrical requirements of the ignition coil. Using a generic, non-certified resistor with an incorrect resistance value can lead to a weak spark (causing poor engine performance and fouling) or can deliver excessive current to the coil, causing it to overheat and fail prematurely. A resistor with an inadequate power rating will quickly burn out, resulting in an in-flight engine shutdown. The genuine OEM part is the only way to guarantee the correct, tested values required for a safe and airworthy ignition system.
The S2041-50B1.6 is a key component in a "boosted" ignition start circuit, a design governed by Ohm's Law (V=IR) and the Power Law (P=I2R). In the normal "RUN" state, the 1.6 \Omega ballast resistor is in series with the primary winding of the ignition coil. The total resistance of this circuit limits the current (I) to a safe, continuous level that prevents the coil from overheating while still allowing it to generate a sufficient spark. In this state, the resistor itself dissipates a significant amount of energy as heat (P=I2R), which is why it is a large, ceramic-bodied power resistor. When the ignition switch is turned to the "START" position, a separate contact in the switch closes a circuit that shorts across (bypasses) the ballast resistor. The total circuit resistance drops dramatically. Although the overall bus voltage (V) is depressed by the heavy load of the starter motor, this sharp decrease in resistance allows a much higher current (I) to flow to the coil. Since the energy stored in the coil's magnetic field—which directly determines the intensity of the spark—is proportional to the square of the current (E=21LI2), this boosted current results in a significantly hotter and more energetic spark, ensuring reliable ignition of the cold, rich fuel mixture during engine start.
Note: This is a flight-critical ignition system component. A failed resistor will cause the engine to shut down or fail to start. This component is designed to operate at high temperatures and must be mounted in its specified location to allow for proper airflow and cooling. All electrical work must be performed by a certified A&P or avionics technician in accordance with the Textron/Cessna maintenance and wiring diagram manuals.
Documentation
The definitive part number applicability and all installation procedures are detailed in the applicable Textron Aviation (Cessna) Illustrated Parts Catalog (IPC) and Wiring Diagram Manual for the specific aircraft model and serial number.