CR3243-4-3 - Cherry Aerospace Rivet Blind

CR3243-4-3 – CherryMAX® Blind Protruding Head Rivet (Oversize)

Available now through the AirParts Aero marketplace.

Overview Section

The Cherry Aerospace CR3243-4-3 (often written as CR3243-4-03) is a high-strength structural blind rivet featuring a universal protruding head. As part of the CherryMAX® product line, it is designed to provide the strength of a solid rivet in applications where only one side of the structure is accessible.

The CR3243 series is the Oversize version of the nominal CR3213.3 In aircraft maintenance and repair (MRO), it is used when a hole has become slightly enlarged during the removal of an old 1/8" rivet. The 0.140" shank diameter (1/64" over nominal) ensures a tight interference fit, restoring the structural integrity of the joint without requiring the technician to upsize to a 5/32" fastener.

Key Features Section

• Mechanically Locked Spindle: Features a "Safe-lock" collar that permanently secures the stem within the rivet sleeve. This prevents the stem from vibrating out, ensuring the rivet remains a structural member and preventing Foreign Object Damage (FOD).

• Bulbed Blind Head: During installation, the sleeve expands into a large "bulb" on the blind side. This distributes the load over a wide area, making it excellent for thin skins and providing high pull-through resistance.

• Oversize Shank (0.140"): Specifically engineered for rework. It provides superior hole-fill in "stressed" or slightly enlarged holes, preventing the "smoking rivet" effect (black oxidation caused by movement).

• Universal Head Style: The protruding head provides a larger bearing surface on the manufactured side, ideal for non-countersunk applications.

• High-Strength Materials: The combination of a 5056 aluminum sleeve and a heat-treated 8740 alloy steel stem provides high shear strength and excellent corrosion resistance.

• Flush Stem Fracture: The pulling stem breaks off flush with the top of the rivet head, requiring no secondary trimming for a finished appearance.

Technical Specifications Section

Aircraft Compatibility Section

The CR3243-4-3 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 wing and control surface structural patches.

• Experimental Aircraft: A favorite for Van’s RV builders when a hole is "messed up" and requires an oversize fastener to maintain structural margins.

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

Technical Applications & Safety

The -03 grip length is intended for a total material thickness (stack-up) of 1/8" to 3/16".

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 CR3243-4-3 lies in its Hole Fill and Fatigue Resistance. Blind rivets are often criticized for lack of hole fill compared to bucked solid rivets. CherryMAX technology addresses this by expanding the sleeve significantly during the initial phase of the pull. In the Oversize configuration, this expansion is tailored to bridge 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. 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.

Product Overview

An item consisting of two or more of the following components: stem, rivet body, sleeve, expander, bolt, and collar. It is a headed fastening device with the shank designed to be expanded by means of a separate or integral stem or mandrel, or bolt and expander. It is designed to be installed or expanded from one side only. Excludes nut, blind assembly.

Specification:

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