MHJ-4003S - Hartzell Engine Technologies 24 Volt Direct Drive Starter Motor

MHJ-4003S – Hartzell Engine Technologies 24 Volt Direct Drive Starter Motor

Available now on the Airparts.aero Marketplace.

Overview

The Hartzell Engine Technologies MHJ-4003S is a genuine, FAA-PMA approved, heavy-duty starter motor, engineered as a direct replacement for the original equipment on a wide range of Continental 520 and 550-series engines. This is a traditional direct-drive starter, valued for its robust construction and time-proven reliability. Manufactured by Hartzell (which now includes the legacy Kelly Aerospace and Prestolite brands), the MHJ-4003S is built to provide the powerful, high-torque cranking performance required to start large-displacement, high-compression piston engines, ensuring dependable starts in all operational environments.

Key Features

• Direct-Drive, High-Torque Design: A powerful, series-wound electric motor that drives the starter clutch and gear directly, without a reduction gearbox. This simple, robust design provides the raw torque needed to turn over large, six-cylinder engines.
• Heavy-Duty Construction: Built with high-quality, heavy-gauge copper windings, robust bearings, and a durable housing to withstand the extreme thermal and mechanical stresses of engine starting.
• Proven Reliability: The direct-drive starter design has a decades-long history of proven reliability in the field, making it a trusted workhorse for a vast portion of the general aviation fleet.
• Direct PMA Replacement: A certified FAA-PMA direct replacement for a range of OEM starters, including the Prestolite MHJ-4003S and Continental 631005, guaranteeing perfect form, fit, and function without any modification.
• Industry-Leading Support: Backed by Hartzell Engine Technologies, a global leader in engine components, ensuring the highest standards of quality control, manufacturing, and product support.

Technical Specifications

• Part Number: MHJ-4003S
• Manufacturer: Hartzell Engine Tech (incorporating Kelly Aerospace / Prestolite technology)
  
• Component Type: Direct-Drive Starter Motor
• Voltage: 24 VDC
• OEM Replacement for: Prestolite MHJ-4003S, Continental 631005
• Primary Function: Engine cranking for startup.
• Certification: FAA-PMA
• Description:   Starter Motor
• Part number:   MHJ-4003S 
• Alternate Part number:   ES646275-1, 646275-1, 637847, PM2407, MHJ-4003, PL13484
• OEM:   Prestolite, Continental
• OEM Part number:   MHJ-4003, 637847, 646275
• FAA Eligibility:   [ Click here ]

Aircraft Compatibility

The Hartzell MHJ-4003S is the specified FAA-PMA replacement starter for numerous high-performance single and multi-engine aircraft powered by Continental's premier large-bore engines. It is imperative to consult the specific aircraft's Illustrated Parts Catalog (IPC) or the current Hartzell application guide for final verification.

• Common Continental Engine Series:
  • IO-520, TSIO-520
  • IO-550, TSIO-550
  • GTSIO-520
• Common Aircraft Platforms:
  • Beechcraft: Bonanza, Baron
  • Cessna: 206, 210, 310, 340, 414, 421
  • Mooney: M20 series (with Continental engines)
  • Cirrus: SR22 (with Continental engines)

Applications

The MHJ-4003S is a flight-critical component essential for engine operation:

• Engine Starting: Its sole function is to convert electrical energy from the battery into the high-torque mechanical energy required to rotate the engine's crankshaft and initiate the combustion cycle.
• Component Overhaul/Replacement: The primary component to replace when the original starter fails to engage, cranks slowly, or draws excessive current.

Why Choose MHJ-4003S?

The ability to reliably start your engine is fundamental to the utility and safety of your aircraft. The Hartzell MHJ-4003S provides the proven performance and robust construction of a traditional direct-drive starter, backed by a modern, industry-leading manufacturer. As an FAA-PMA approved part, it meets or exceeds the specifications of the original equipment, offering a high-quality, airworthy, and cost-effective solution for replacing a tired or failed starter. For trusted performance, the Hartzell direct-drive starter is the professional's choice.

Order Your Hartzell MHJ-4003S Starter Now

Ensure reliable starts for your high-performance engine with a robust, FAA-PMA certified starter from Hartzell Engine Tech. Visit Airparts.aero to inquire about new or remanufactured MHJ-4003S starters today.

The Hartzell MHJ-4003S is a series-wound DC motor. In this classic, high-torque design, the field coils (on the stator) and the armature coils (on the rotor) are connected in series. This configuration produces the maximum possible torque at zero RPM (stall torque), which is ideal for overcoming the high initial inertia and compression of a large piston engine. The starter transmits this torque to the engine's ring gear via a Bendix-style overrunning clutch drive, which automatically engages and disengages. The direct-drive nature means the armature rotates at the same speed as the output gear, providing a simple and extremely durable power transmission path.

Note: This is a flight-critical, high-amperage electrical component. Installation must be performed by a certified A&P mechanic. Ensure the battery is disconnected before installation. All electrical connections must be clean and torqued to the specified value to prevent high resistance and heat buildup. The condition of the engine's starter ring gear should be inspected before installing a new starter.  



Product Overview:

Every Hartzell Engine Technologies starter line reveals true aviation design/development and are capable of being maintenance free to your Lycoming engine’s TBO… and beyond. Each of the aircraft starters provide High Torque, Low Inrush & Operating Current Draw, and a Superior Duty Cycle. Along with major weight savings from the old Prestolite heavyweights, the new Hartzell Engine Technologies starters are suitable for installation on all Lycoming engines without modification. 

Application Chart:   [ Click here ]
Maintenance Information:   [ Click here ]
Troubleshooting:   [ Click here ]

AirParts stocks thousands of engine and engine overhaul parts. Cranks, cases, cams, cylinders, and more. Most available on exchange programs.