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0850469-1 – Textron Aviation OEM Starter Relay Assembly
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Overview
The Textron Aviation 0850469-1 is the genuine OEM, flight-critical starter relay assembly (also known as a starter solenoid or contactor) for a wide range of modern 24-volt Cessna single-engine aircraft. This is a heavy-duty, remote-controlled electromechanical switch, engineered to perform one of the most demanding tasks in the aircraft's electrical system: safely handling the immense inrush current required to engage the starter motor. A direct connection from the cockpit ignition switch to the starter is impractical and unsafe due to the hundreds of amps involved. Instead, the ignition switch sends a low-current signal to this relay, which then closes its high-power internal contacts to complete the circuit between the battery and the starter.
Mounted on the firewall, this relay is designed to withstand the extreme heat and vibration of the engine compartment. Its robust construction features high-conductivity copper studs for the main power circuit and a fully sealed housing to protect the internal coil and contacts from moisture and contaminants. The reliability of this component is paramount; its failure means the engine cannot be started.
Key Features
Genuine Textron Aviation OEM Part: The only part certified and approved for this application, guaranteeing correct voltage, current rating, and environmental resistance.
High-Current Switching Capability: Specifically designed to handle the massive, instantaneous current draw (often >300 amps) of the starter motor without arcing or welding the contacts.
Robust, Sealed Construction: The sealed case protects the internal coil and high-power contacts from the harsh firewall-forward environment, ensuring long-term reliability.
Vibration and Heat Resistant: Engineered and tested to perform flawlessly under the constant vibration and high ambient temperatures of the engine compartment.
Flight-Critical Component: Essential for all engine starting operations, making it a "no-go" item if inoperative.
Technical Specifications
Part Number: 0850469-1
Component Type: Starter Relay / Solenoid / Contactor
OEM Manufacturer: Textron Aviation (Cessna)
Voltage Rating: 24 VDC (for 28V nominal aircraft systems)
Duty Cycle: Intermittent (rated for engine start cycles)
Contact Configuration: Single Pole, Single Throw (SPST), Normally Open (NO)
Terminals: High-current copper studs for the main circuit; smaller threaded posts for the control circuit.
Aircraft Compatibility
This starter relay is the specified OEM part for a wide range of 24-volt Cessna piston aircraft, including but not limited to:
Cessna: 172R, 172S, R172, 182S, 182T, T182T, 206H, T206H
Note: This compatibility list is for general reference. Applicability can vary by aircraft serial number. The aircraft's specific Illustrated Parts Catalog (IPC) is the sole and final authority for determining part applicability.
Applications
Engine Starting System: Acts as the primary, high-current switch that connects the aircraft battery to the starter motor upon command from the cockpit ignition switch.
Electrical System Safety: Isolates the high-amperage starting circuit from the low-amperage cockpit switches and wiring, preventing a major fire hazard.
Why Choose 0850469-1?
The starter relay is a classic single point of failure. If it doesn't work, you're not flying. Using a non-certified, automotive, or "will-fit" relay is an extreme safety risk. Such parts are not designed for the specific current loads or the harsh environmental conditions of an aircraft engine compartment. A failed relay can leave you stranded. Even worse, a relay that fails with its contacts welded shut can lead to an in-flight starter engagement (destroying the starter and potentially the engine's ring gear) or an unstoppable electrical drain that can lead to a fire. The genuine Textron OEM 0850469-1 is the only part guaranteed to meet the stringent performance and safety specifications required for your aircraft.
The engineering principle that necessitates the use of the 0850469-1 relay is a fundamental application of electrical power management and Ohm's Law. To deliver the hundreds of amps required by a starter, the connecting cables must be very large and very short to minimize power loss due to resistance ($$P_{loss} = I^2R$$). Running such heavy cables all the way to the cockpit and back would add significant weight, cost, and a massive fire hazard. The relay, acting as a remote contactor, solves this problem. It allows the heavy, high-current cables to be kept short, running only from the nearby battery to the relay and then to the starter. A small, lightweight, low-current wire is then safely routed to the cockpit ignition switch. When the pilot turns the key, this low-current circuit energizes the relay's internal electromagnet, which provides the powerful force needed to close the main contacts and switch the high-current load. This is a classic and essential design for a safe and efficient high-power electrical system.
Note: The 0850469-1 is a flight-critical electrical component. Installation must be performed by a certified A&P mechanic. All high-current electrical terminals must be clean, free of corrosion, and torqued to the values specified in the Textron Aviation maintenance manual to prevent high-resistance connections, which can generate extreme heat and lead to failure.
Documentation
No public-facing OEM specification sheet was located for this proprietary part number. All authoritative technical data, installation procedures, and wiring diagrams are contained within the official Textron Aviation Maintenance Manual and Illustrated Parts Catalog (IPC) for the applicable aircraft models.
