CR3243-4-4 - Cherry Aerospace Universal Head Cherrymax Blind Rivet

CR3243-4-4 – CherryMAX® Blind Protruding Head Rivet (Oversize)

Available now through the AirParts Aero marketplace.

Overview Section

The Cherry Aerospace CR3243-4-4 (often listed as CR3243-4-04) is a high-strength structural blind rivet featuring a universal protruding head.1 Part of the CherryMAX® family, it is designed to provide the strength of a solid rivet in areas where the backside of the work is inaccessible.

The CR3243 series is specifically an Oversize variant. It is the primary choice for maintenance technicians when a standard 1/8" rivet hole has been slightly enlarged or damaged during the removal of an old fastener. With a shank diameter of 0.140 in (1/64" larger than nominal), it ensures a tight, structural interference fit without the need to upsize to a 5/32" fastener.

Key Features Section

• Mechanically Locked Spindle: Features a "Safe-lock" collar that permanently secures the stem into the rivet sleeve, preventing the stem from vibrating loose—a critical safety feature in high-vibration airframe areas.

• Bulbed Blind Head: During installation, the sleeve forms a large "bulb" on the blind side, providing a wide bearing surface that prevents pull-through in thin skins or composite materials.

• One-Tool Versatility: Designed with an integral driving anvil, allowing it to be installed using standard pulling heads without the need for specialized nose-piece changes.

• Flush Stem Fracture: The stem breaks off clean and flush with the manufactured head, providing a finished look and consistent structural strength.

• Visual Inspectability: The locking collar is visible from the manufactured head side after installation, allowing for immediate quality verification.

• Oversize Shank (0.140"): Specifically engineered to provide superior hole-fill in previously stressed or enlarged holes, preventing "smoking rivets."

Technical Specifications Section

Aircraft Compatibility Section

The CR3243-4-4 is widely used in structural repairs across various airframes:

• Textron Aviation (Cessna/Beechcraft): Standard for repairs on fuselage skins, ribs, and bulkheads on the Cessna 172, 182, and King Air models.

• Piper Aircraft: Utilized in the PA-28 and PA-32 series for structural patches on wing and control surfaces.

• Experimental Aircraft: A favorite for Van’s RV builders when a hole in a 1/8" line is accidentally enlarged during drilling.

• General MRO: Used in secondary structures on Boeing and Airbus regional jets where blind access is required.

Technical Applications & Safety

The -04 grip length is intended for a total material thickness (stack-up) of 3/16" to 1/4".

Safety Warning: Hole preparation is critical. Because this is an Oversize rivet, you cannot use a standard #30 (0.128") drill bit. You must use a #27 drill bit (0.144"). If the hole is too tight, the rivet sleeve will be damaged during installation, or the locking collar will fail to seat. Always use a grip gauge to verify the material thickness; a rivet with a grip that is too short will not form a proper bulb, leading to structural failure under load.

Technical Engineering Insight

The engineering value of the CR3243-4-4 lies in its Hole Fill and Fatigue Resistance. In the Oversize configuration, the rivet sleeve is designed to expand more aggressively than a nominal fastener. This bridges the gap in worn holes, effectively "re-prestressing" the joint. This prevents localized stress concentrations that lead to fatigue cracking in aluminum skins, significantly extending the life of the repair compared to standard non-locking blind fasteners.

Installation & Maintenance Addendum

1. Tooling: For optimal results, use a Cherry G704B or G747 power tool. For field repairs, a manual G29 hand tool is sufficient but requires more physical effort due to the steel stem.

2. Driving Anvil: These rivets come with a silver-colored driving anvil (the small washer on the stem) to identify them as Oversize.4 Nominal rivets typically use a gold-colored anvil.

   
   

   
   

3. Inspection: Post-installation, verify that the locking collar (visible on top of the head) is fully seated. If the stem is protruding or the collar is missing, the rivet must be drilled out and replaced.

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Alternate Part Numbers: CR3243-4-04, M7885/6-4-04, MS20470

Cherry Textron Cherrymax® rivets are the industry standard blind rivets. They are structurally rated, which means that they are just as strong as a solid rivet and can be used anywhere as solid rivet can be used. The flush fracturing stem breaks off cleanly to produce a smooth domed or flush head upon proper installation.

Item Specification:

CR3243-4-4 - Cherry Aerospace Universal Head Cherrymax Blind Rivet

The CR3243-4-4 Cherrymax Blind Rivet by Cherry Aerospace is an advanced fastening solution used extensively in aircraft assembly and maintenance. This universal head rivet features a high-strength aluminum alloy body with a stainless steel mandrel, ensuring robust and reliable performance under extreme conditions. It is specifically engineered for applications requiring superior shear and tensile strength, making it ideal for structural areas subject to high stress and vibration. The rivet's self-plugging design provides consistent and secure fastening, while its blind installation capability allows for easy application in areas with limited access.

Technical Specifications:

• Diameter: 1/8 inch (4)
• Grip Range: 0.188 - 0.250 inches
• Material: Aluminum body, stainless steel stem
• Head Type: Universal head
• Compliance: Meets MIL-R-7885 and NAS9301 standards

Applications: The CR3243-4-4 is used in aerospace applications, particularly in the assembly of airframe structures, control surfaces, and other critical components. Its design ensures maximum joint integrity and reliability in high-vibration and high-load environments.

EQUIVALENT TO HUCK PART NUMBER HC3243-04-04