CR3242-4-2 - Cherrymax Oversized Blind Rivet

CR3242-4-5 – CherryMAX® Blind Flush Rivet (Oversize)

Available now through the AirParts Aero marketplace.

Overview Section

The Cherry Aerospace CR3242-4-5 (often written as CR3242-4-05) is a high-strength structural blind rivet featuring a 100° flush (countersunk) head. It is part of the legendary CherryMAX® line, known for being the "all-in-one" blind fastener that provides the structural integrity of a solid rivet with the convenience of blind installation.

The CR3242 series is specifically an Oversize variant. In aircraft maintenance, when an original 1/8" rivet is drilled out, the hole often becomes slightly enlarged. This oversize rivet features a shank diameter approximately 1/64" larger than nominal (actual diameter 0.140"), allowing it to fill the expanded hole and maintain a tight, structural fit without the need to upsize to a 5/32" fastener.

Key Features Section

• Locked Spindle Design: Features a mechanical "Safe-lock" collar that permanently locks the stem into the sleeve, ensuring the stem cannot vibrate loose or fall out (FOD prevention).

• Bulbed Blind Head: During installation, the rivet sleeve "bulbs" out on the blind side, creating a large bearing surface. This makes it ideal for thin sheets or composite materials where pull-through is a concern.

• One-Tool Installation: The CherryMAX system includes an integral installation washer, allowing various diameters and styles to be installed with a single pulling head.

• Flush Fracturing Stem: The stem breaks off flush with the rivet head, providing a smooth, aerodynamic finish that requires no secondary shaving or trimming.

• Oversize Shank: The 0.140" diameter is the industry standard for repair work, ensuring structural hole-fill in previously drilled-out locations.

• Visual Inspectability: The locking collar is visible after installation, allowing for a quick, positive confirmation of a successful structural bond.

Technical Specifications Section

Aircraft Compatibility Section

The CR3242-4-5 is a ubiquitous repair fastener across nearly all metallic airframes:

• Textron (Cessna/Beechcraft): Approved replacement for Part Numbers 132272A405 and S2457-4-5.6

• Piper Aircraft: Standard for structural repairs on PA-28 and PA-32 control surfaces.

• Boeing 737 / 747 / 767: Utilized in secondary structures and cabin furnishings where blind access is required.

• Experimental / Van’s Aircraft: Frequently used in "blind spots" on the RV-series where a bucking bar cannot reach the back of a 1/8" solid rivet.

Technical Applications & Safety

CherryMAX rivets are structurally rated, meaning they can often be used in place of AD-series solid rivets (per SRM or engineer approval).7

Safety Warning: Do not use a standard #30 drill bit. Because this is an Oversize rivet, a standard 1/8" (#30) hole is too small. Use a #27 drill bit to ensure the proper 0.143"–0.146" hole clearance. Additionally, ensure the total material stack-up falls within the 0.251" to 0.312" grip range; using a rivet that is too long or too short will compromise the shear strength of the joint.8

Technical Engineering Insight

The engineering value of the CR3242-4-5 lies in its Mechanical Joint Integrity. Unlike standard "pop" rivets, the CherryMAX stem becomes an integral part of the load-bearing structure once locked. In the 5056 Aluminum/Alloy Steel combination, the steel stem provides the shear strength, while the aluminum sleeve provides the corrosion resistance. The Oversize shank is particularly engineered for "Sheet Metal Rework"; it expands during the pulling process to provide 100% hole fill, preventing vibration-induced wear.

Installation & Maintenance Addendum

1. Tooling: Use a Cherry G704B, G747, or G27 power tool for best results. Hand tools (like the G29) can be used for small quantities but require significant force.

2. Deburring: Always deburr the hole before installation. Any metal shavings trapped between the sheets will prevent the rivet from pulling the materials together tightly.

3. Visual Check: After pulling, ensure the gold-colored locking collar is seated flush within the rivet head. If the stem is sticking out or the collar is missing, the rivet must be replaced.

Product Specification: