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 or "smiled." 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.4 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, eliminating tool-switching time.
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 (1/64" over nominal 1/8") 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
| Specification | Detail |
| Part Number | CR3242-4-5 (or CR3242-4-05) |
| Manufacturer | Cherry Aerospace (Textron) |
| Head Style | 100° Flush Head (Countersunk) |
| Diameter | 1/8" Oversize (Actual: 0.140 in) |
| Grip Range | 0.251 in – 0.312 in (Size -05) |
| Sleeve Material | 5056 Aluminum Alloy |
| Stem Material | 8740 Alloy Steel |
| Shear Strength | 530 lbs (Typical for -4 diameter) |
| Hole Size Required7 | #27 Drill Bit (0.143 – 0.146 in)8 |
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 S2457-4-5.9 Used extensively in wing skin and fuselage repairs.
Piper Aircraft: Standard for structural repairs on PA-28 and PA-32 control surfaces.
Boeing 737 / 747 / 767:10 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).11
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. Forcing the rivet into a small hole can damage the locking collar or lead to an incomplete bulb formation. 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.12
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 and compatibility with the aircraft skin. The Oversize shank is particularly engineered for "Sheet Metal Rework"; it expands during the pulling process to provide 100% hole fill, preventing the "smoking rivet" (vibration-induced wear) that occurs when a fastener is loose in its hole.
Installation & Maintenance Addendum
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 physical force for steel-stem rivets.
Deburring: Always deburr the hole before installation. Any metal shavings trapped between the sheets will prevent the rivet from pulling the materials together tightly, leading to a "gapped" joint.
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 drilled out and replaced.