390-389001-0001 - Textron Aviation OEM Ametek Starter Generator

390-389001-0001 – Textron Aviation OEM Ametek Starter Generator (300 Amp)

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Overview

The Textron Aviation 390-389001-0001 is the genuine OEM, flight-critical Starter Generator for the Beechcraft King Air 350 (B300 series) aircraft. Manufactured by Ametek, this is a heavy-duty, dual-function component that is the heart of the aircraft's electrical and starting systems. Its dual role is paramount: first, it acts as a powerful, high-torque electric motor to spool the PT6A turbine engine for starting. Second, once the engine is running, it is driven by the accessory gearbox to serve as the aircraft's primary, high-output 300 Amp DC generator, providing all necessary electrical power for the avionics, anti-ice, and other systems while also charging the battery.

This unit is engineered for the extreme demands of the turboprop environment, built to withstand high temperatures, vibration, and continuous-duty operation. Its reliability is non-negotiable for the safe operation of the aircraft.

Key Features

• Genuine Textron Aviation OEM Part: The original, factory-specified component (manufactured by Ametek), guaranteeing perfect fit, form, and function.

• Flight-Critical Dual Function: Serves as both the engine starter and the primary 300 Amp DC generator.

• High-Output Electrical Power: Provides 300 Amps of continuous, stable 28 VDC power, essential for the high-demand electrical systems of a King Air 350.

• High-Torque Starter Motor: Engineered to provide the immense torque required to overcome engine inertia and provide a fast, cool start, which is critical for prolonging turbine life.

• Durable & Reliable: Designed and tested for a long service life in the harsh, high-heat, high-vibration environment of the engine nacelle.

• Forced-Air Cooled: Designed for a mandatory blast tube connection to ensure proper cooling and prevent overheating under high electrical loads.

Technical Specifications

• Part Number: 390-389001-0001

• Component Type: Starter Generator

• OEM Manufacturer: Textron Aviation (Original Mfr: Ametek)

• Ametek P/N (Reference): 5002498-4

• Voltage: 28 VDC

• Current Rating: 300 Amps (Continuous)

• Drive: Splined Shaft (Engine Accessory Gearbox)

• Cooling: Forced Air (Blast Tube Required)

• JASC Code: 8011 - AC Generation

Aircraft Compatibility

• Beechcraft (Textron Aviation): King Air 350 (B300 Series)

Note: This is a flight-critical component. The aircraft's specific Illustrated Parts Catalog (IPC) for a given serial number is the final and absolute authority for determining part applicability.

Applications

• Engine Starting: Provides the rotational torque to spool the PT6A-60A engine's compressor section for starting.

• Primary Electrical Power: Serves as the main DC generator, powering all aircraft systems in flight (avionics, anti-ice, lighting, etc.).

• Battery Charging: Provides the current to charge the aircraft's main battery and maintain its state of charge.

Why Choose 390-389001-0001?

In a twin-turboprop, the starter-generators are the foundation of the entire electrical system. A failure of one unit places the entire electrical load on the remaining generator, and a dual failure is a catastrophic emergency. The genuine Textron/Ametek 390-389001-0001 is the only component guaranteed to meet the exact performance specifications of the King Air 350. Using a non-certified or improperly overhauled part introduces an extreme risk of insufficient starting torque (leading to hot starts), unstable voltage (damaging avionics), or premature failure from bearing or brush burnout. For the safety and dispatch reliability of your aircraft, there is no substitute for this genuine OEM part.

The engineering brilliance of the 390-389001-0001 is that it is a compound-wound DC machine designed to perform two inverse functions. As a starter (motor mode), it operates as a series-wound motor. The high starting current flows through both the armature and the heavy-gauge series field windings, producing the massive magnetic flux required for maximum breakaway torque ($$T \propto \Phi I_a$$). Once the engine reaches a self-sustaining speed, the Generator Control Unit (GCU) de-energizes the starter circuit and energizes the shunt field windings. Now being driven by the engine's accessory gearbox, the unit transitions to generator mode. The GCU continuously modulates the current to the shunt field, precisely controlling the strength of the magnetic field to maintain a constant, rock-solid 28VDC output, regardless of variations in engine RPM or aircraft electrical load.

Note: The 390-389001-0001 is a flight-critical component. Installation must be performed by a certified A&P/IA mechanic. It is essential to ensure the splined shaft is properly lubricated and engaged, the unit is securely mounted, and the blast tube cooling duct is correctly attached. The main "B-lead" electrical terminal must be clean and torqued to the exact value specified in the maintenance manual to prevent a high-resistance connection, which will 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 inspection criteria are contained within the official Textron Aviation Beechcraft King Air 350 Series Maintenance Manual and Illustrated Parts Catalog (IPC).

CORE DEPOSIT $12,500.00

Description:   Starter Generator
Part Number:   390-389001-0001
Model Number:   MG94A-1
FAA Eligibility:   [ Click Here ]

Features:

• Application: Engine 
• 28 VDC power
• 150-400 Amp continuous load range
• Aircraft Models:
  •  Beechcraft Jet 390 Premier 1, 1A
    
    
    
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