654490 - Continental Connecting Rod Nut 0.44-20

654490 – Continental Connecting Rod Nut 0.44-20

Available now on the Airparts.aero Marketplace.

Overview

The Continental 654490 is a flight-critical, high-stress connecting rod nut engineered specifically for use on a wide range of Continental aircraft engines. This is not a standard piece of hardware; it is a precision-manufactured component designed to secure the connecting rod cap to the connecting rod body, a joint that is subjected to immense tensile and compressive forces during engine operation. Manufactured from a superior-grade, high-tensile steel alloy, the 654490 is designed to be torqued to a specific stretch value to achieve the precise clamping force necessary to maintain the integrity of the rotating assembly. It is a mandatory replacement item during any engine overhaul or when a connecting rod is disassembled.

Key Features

• High-Tensile Steel Alloy: Forged from a specialized, high-strength steel alloy, heat-treated to achieve the optimal balance of tensile strength and ductility required to withstand millions of stress cycles without fatigue.
• Precision-Rolled Threads: Features smooth, rolled 0.44-20 UNF threads for maximum engagement and resistance to stripping. The rolling process creates a superior grain structure compared to cut threads, significantly enhancing fatigue life.
• Engineered for Stretch: Specifically designed to elongate a precise amount when the specified torque is applied. This "stretch" is what provides the critical and consistent clamping force on the bearing journal.
• Mandatory Replacement Part: Universally designated as a single-use component. Once torqued to specification and subsequently removed, it must be discarded and replaced to ensure safety and reliability.
• Genuine Continental Part: As a genuine OEM part, it guarantees conformance to the strict material and manufacturing standards required by Continental's Type Certificate Data Sheets (TCDS) and the FAA.

Technical Specifications

• Part Number: 654490
• Component Type: Connecting Rod Bolt Nut
• Thread Specification: 7/16-20 UNF (0.4375-20)
• Wrench Size: 1/2" (12-point socket recommended)
• Material: High-Tensile, Heat-Treated Steel Alloy
• Application Method: Torque-to-stretch
• Recommended Torque: Varies by engine model; must be referenced from the current Continental Overhaul Manual (e.g., 40-45 ft-lbs for many models).
• Certification: FAA Production Approval

Engine Compatibility

The Continental 654490 connecting rod nut is specified for use across a vast range of Continental's most successful and long-running engine series. It is imperative to consult the specific engine's Illustrated Parts Catalog (IPC) and Overhaul Manual to verify the correct part number and installation procedure.

• Compatible Engine Series:
  • O-300, GO-300
  • O-470, IO-470, TSIO-470
  • IO-520, TSIO-520
  • GTSIO-520
  • IO-550, TSIO-550

Applications

The 654490 nut has one singular, flight-critical application:

• Engine Rotating Assembly: Used in pairs to fasten the connecting rod cap to the connecting rod, securing the crankpin bearing. This application is fundamental to the engine's ability to convert combustion pressure into rotational force.
• Mandatory Overhaul Component: Must be replaced with new units whenever connecting rods are serviced or the engine is overhauled.

Why Choose 654490?

In an aircraft engine, there is no room for compromise on critical fasteners. The 654490 is the only part certified by the engine manufacturer to provide the required clamping force and fatigue resistance for this high-stress joint. Using a genuine Continental part ensures you are installing a component with a known material pedigree and manufacturing process, which is essential for the safety and reliability of the engine. Attempting to substitute this part or reuse an old one risks catastrophic engine failure. For A&P mechanics and engine builders, using a new set of 654490 nuts is a non-negotiable step in a professional and airworthy engine build.

Order Your 654490 Connecting Rod Nuts Now

Ensure the integrity and safety of your engine overhaul with genuine Continental connecting rod nuts. Visit Airparts.aero to order your set of 654490 nuts today.

The Continental 654490 nut is an integral part of a bolted joint system designed to operate under intense, cyclical tensile loading. The engineering principle behind its use involves tightening the fastener to a predetermined preload (clamping force) that exceeds the maximum separating force it will encounter in service. This is achieved by torquing the nut to stretch the connecting rod bolt into its elastic region. A properly preloaded 654490 nut ensures the joint remains tightly clamped throughout the engine's operational cycle—from the compression stroke to the peak tensile load during the exhaust/intake strokes at high RPM. This prevents microscopic slippage between the rod and cap, which would otherwise lead to fretting, bearing damage, and eventual fatigue failure of the bolts. Therefore, the use of a new, certified 654490 nut and adherence to the manufacturer's multi-stage torque procedure is not merely a recommendation, but a fundamental requirement for a durable and airworthy engine.

Note: This is a single-use, flight-critical component. It MUST be replaced with a new part every time it is loosened. Installation must be performed by a certified A&P mechanic in strict accordance with the current, applicable Continental Motors Overhaul Manual, paying close attention to lubrication and multi-stage torque application procedures.

Attached to connecting rod bolt to attach connecting rod to piston and crankshaft.

This part superseded 628109, 631554

Aftermarket PMA part available:
Superior Air Parts - SA631554 for certain engine types.

Fits Continental piston engines: GTSIO-520 -C, -D, -F, -H, -K, -L, -M, -N