71652 - Lycoming Engines Crankshaft Gear Assembly

71652 – Lycoming Engines Crankshaft Gear Assembly

Available now on the Airparts.aero Marketplace.

Overview

The Lycoming 71652 is a genuine OEM crankshaft gear, a flight-critical component that serves as the heart of the engine's timing and accessory drive system. This precision-machined gear is installed on the rear of the crankshaft and is responsible for transmitting the engine's rotation to both the camshaft and the entire accessory gear train. Manufactured from a high-strength, case-hardened steel alloy, the 71652 is engineered to withstand immense torsional loads and provide perfect, life-long timing for thousands of hours of reliable service. As a genuine Lycoming part, it guarantees the material integrity and exacting tolerances required for a professional, airworthy engine build.

Key Features

• Master Timing Component: This is the primary drive gear in the engine. It directly meshes with the camshaft gear, establishing the precise 2:1 ratio required to synchronize the opening and closing of the engine's valves with the movement of the pistons.
• Accessory Drive Function: Initiates the power transmission through the accessory gear train, driving essential engine components including both magnetos, the oil pump, and the mechanical fuel pump.
• Case-Hardened Steel Construction: Fabricated from a high-strength steel alloy and then case-hardened. This process creates an extremely hard, wear-resistant outer surface on the gear teeth while maintaining a more ductile core to resist shock loads and prevent tooth fracture.
• Precision Machined: The gear teeth are hobbed and ground to a precise involute profile, ensuring smooth, quiet operation and an even distribution of loads between meshing gear teeth, which is critical for preventing premature wear.
• Genuine Lycoming OEM Part: As a genuine factory component, it guarantees conformance to Lycoming's stringent metallurgical standards, heat treatment processes, and quality control, ensuring the highest level of safety and performance.

Technical Specifications

• Part Number: 71652
• Component Type: Crankshaft Gear
• Material: Case-Hardened Steel Alloy
• Primary Function: Drives Camshaft and Accessory Gear Train
• Installation: Press-fit or shrink-fit onto the rear of the crankshaft, located by a dowel pin.
• Features: Includes timing marks for proper engine assembly.
• Certification: FAA Production Approval

Aircraft Compatibility

The Lycoming 71652 is one of the most widely used internal engine components in the general aviation fleet, specified for use in a vast range of Lycoming's most popular 4-cylinder and 6-cylinder direct-drive engines.

• Common Engine Series:
  • O-320, IO-320, AIO-320, AEIO-320
  • O-360, IO-360, AIO-360, AEIO-360
  • O-540, IO-540, TIO-540, AEIO-540
• Common Aircraft Platforms:
  • A vast range of aircraft from Cessna, Piper, Beechcraft, Mooney, and numerous experimental designs that utilize the above Lycoming engine series.

Applications

The 71652 is a fundamental component for engine assembly and overhaul:

• Engine Timing & Synchronization: Its installation is a critical step in setting the engine's internal valve timing, which is fundamental to the engine's ability to produce power.
• Engine Overhaul: A mandatory inspection item during any engine overhaul. It is inspected for pitting, scoring, and tooth wear, and replaced if any out-of-limit conditions are found to ensure the reliability of the rebuilt engine.

Why Choose 71652?

The crankshaft gear is the single component responsible for driving every other timed event and accessory in the engine. Its failure would be instantaneous and catastrophic. Using a genuine Lycoming 71652 OEM gear is the only way to ensure the part has the correct material composition, case hardening depth, and tooth profile specified by the engine's designers. The risks associated with using a non-certified part with an unknown history or material pedigree are unacceptable. For any professional engine build, the integrity of this gear is paramount.

Order Your Lycoming 71652 Crankshaft Gear Now

Build your engine with the proven reliability and certified quality of genuine Lycoming components. Visit Airparts.aero to order your 71652 crankshaft gear today.

The 71652 crankshaft gear is the first component in the engine's complex gear reduction and power transmission system. The crankshaft rotates at engine RPM, and this gear, having a specific number of teeth, meshes with the camshaft gear, which has exactly twice the number of teeth. This creates a precise 2:1 reduction, ensuring the camshaft—and by extension, the valves—operate at exactly half of crankshaft speed, which is required for a four-stroke engine cycle. The 71652 also meshes with an idler gear, which then reverses the direction of rotation and drives the magneto and oil pump gears. The precise geometry and backlash between the 71652 and these mating gears is critical for quiet operation and long component life.

Note: This is a flight-critical engine internal component. Installation must be performed by a certified A&P mechanic or at a qualified engine overhaul facility in strict accordance with the current Lycoming Overhaul Manual. The installation process typically requires specialized tools and heating/cooling procedures to achieve the proper shrink fit onto the crankshaft.