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55006 – Hartzell Engine Technologies OEM Spacer Washer
Available now on the Airparts.aero Marketplace.
Overview
The Hartzell Engine Technologies 55006 is a genuine OEM, flight-critical starter adapter spacer washer, a primary structural and alignment component for a wide range of Lycoming engines. This is not a standard hardware washer; it is a precision-ground, hardened steel spacer engineered to establish and maintain the critical clearance and alignment within the starter adapter assembly. The 55006's exact thickness is fundamental to the proper operation of the starter clutch and gear train. Its integrity ensures the reliable transmission of torque during engine start while preventing binding or excessive wear on internal components.
Manufactured by Hartzell Engine Tech (incorporating the trusted Kelly Aerospace brand), this spacer guarantees the certified material strength and microscopic dimensional tolerances required for this high-torque, flight-critical application.
Key Features
Precision Ground Thickness: The washer is precision ground to an extremely tight dimensional tolerance for thickness. This precise dimension is critical for setting the correct end play and clearances within the starter adapter's gear and clutch assembly, ensuring smooth and reliable engagement.
Hardened Bearing Steel Construction: Fabricated from a high-grade, heat-treated bearing steel alloy. This provides an extremely hard, wear-resistant surface that can withstand the high compressive and rotational shear loads of the starter adapter without deforming or galling.
Manages Axial & Torsional Loads: Its primary function is to act as a precision spacer and thrust bearing surface. It properly locates the starter gear and clutch assembly, managing the axial loads that are generated as the starter gear engages with the engine's ring gear.
Ensures Drivetrain Alignment: A correctly dimensioned spacer is essential for maintaining the alignment of the starter adapter's internal gear train, preventing premature wear of gear teeth and bearings.
Genuine OEM Component: As a genuine Hartzell component, it guarantees conformance to the exact material specifications, heat treatment, and dimensional tolerances required by the original engine and starter adapter design.
Technical Specifications
Part Number: 55006
Component Type: Starter Adapter Spacer Washer / Thrust Washer
OEM Manufacturer: Hartzell Engine Technologies (Kelly Aerospace)
Material: High-Strength, Hardened Bearing Steel
Finish: Precision Ground
Dimensions:
Inside Diameter: 0.328 inches
Outside Diameter: 0.562 inches
Primary Function: Provides precise spacing and load-bearing surface within a starter adapter assembly.
Certification: FAA-PMA
Aircraft Compatibility
The Hartzell 55006 is a critical internal component for the starter adapter assemblies on a vast number of Lycoming-powered aircraft, making it a key part for a significant portion of the general aviation fleet.
Common Lycoming Engine Series:
O-320, IO-320, LIO-320, AIO-320, AEIO-320
O-360, IO-360, LIO-360, AIO-360, AEIO-360
O-540, IO-540, TIO-540, AEIO-540
Common Aircraft Platforms:
A vast range of aircraft from Piper, Cessna, Beechcraft, Mooney, and numerous experimental designs that utilize the above Lycoming engine series with a starter adapter.
Why Choose 55006?
A failure within the starter adapter, often caused by incorrect clearances or worn components, can result in a "no-crank" situation, leaving an aircraft stranded. In a worst-case scenario, it can cause the starter to remain engaged, leading to catastrophic damage. The Hartzell 55006 is the genuine, certified component designed to ensure this critical assembly is properly spaced and aligned. Using a precision-ground, OEM-quality spacer is the only way to guarantee the internal clearances are set to the manufacturer's exact specifications, ensuring a reliable and long-lasting starter system.
The Hartzell 55006 is a critical element in controlling the end play of the starter adapter's main shaft and gear assembly. The starter adapter contains a spring-loaded, overrunning clutch that must have a precise amount of axial (fore-and-aft) movement to engage and disengage properly. The 55006 spacer washer, with its precision-ground thickness, is a key component in the "stack-up" of parts that defines this movement. If the spacer is too thin, the assembly will have excessive end play, which can cause the gear teeth to mesh improperly and lead to damage. If the spacer is too thick, it can cause the clutch and bearings to bind, leading to starter failure. This small washer's dimensional accuracy is therefore fundamental to the correct mechanical operation of the entire starter adapter system.
Note: This is a flight-critical engine internal component. Installation must be performed by a certified A&P mechanic, typically during the overhaul or repair of an engine starter adapter, in strict accordance with the current Lycoming maintenance and overhaul manuals. Proper measurement of clearances is essential during assembly.
