CR3242-4-1 - Cherry Aerospace CherryMax Oversized Blind Flush Rivet

CR3242-4-1 – CherryMAX® Blind Flush Rivet (Oversize)

Part Number: CR3242-4-1 (also referenced as CR3242-4-01)

Manufacturer: Cherry Aerospace (A PCC Company)

Military Specification: NAS1097 / MIL-R-7885

Overview Section

The CR3242-4-1 is a high-strength oversize structural blind rivet featuring a 100° flush (countersunk) head. Part of the industry-leading CherryMAX® family, this fastener is engineered specifically for thin-gauge sheet metal applications where the reverse side is inaccessible.

The "42" series designation identifies this as an oversize diameter rivet. It is designed with a shank diameter 1/64" larger than the nominal 1/8" standard. This makes the CR3242-4-1 the primary engineering solution for repairing "working" or "smoking" rivets where the original hole has been slightly enlarged by vibration or during the removal of the previous fastener. By stepping up to this oversize rivet, technicians can restore a precision interference fit, ensuring the structural integrity and aerodynamic smoothness of the airframe.

Enhanced Technical Data

Advanced Engineering & Structural Application

The CR3242-4-1 is optimized for Thin-Skin Structural Repairs. With a grip range of 0.045" to 0.062", it is specifically designed for the outermost layers of the aircraft skin, such as attaching a .025" skin to a .025" rib or frame.

Engineering Insight: NAS1097 Reduced Head Design

The flush head follows the NAS1097 standard, often called a "shear head." This design features a shallower head height compared to standard MS20426 rivets. This is critical for thin-skin applications because it prevents the countersink from "knife-edging" (penetrating completely through) the top sheet of metal. This ensures a cylindrical bearing surface remains in the hole, significantly improving the fatigue life of the repair.

The CherryMAX Mechanical Lock

Unlike standard blind rivets where the mandrel can fall out, the CR3242 features a Safe-Locking collar. During installation, a driving anvil on the rivet shears a small collar into a groove on the stem. This locks the 8740 steel stem permanently in place, allowing it to act as a structural member that shares the shear load with the aluminum sleeve.

Aircraft Compatibility

The CR3242-4-1 is a standard stock item for MRO facilities servicing:

• Textron Aviation: Cessna 100/200 series and Beechcraft Bonanza/Baron skin repairs.

• Bombardier: CRJ and Challenger series fairing and secondary structure maintenance.

• Piper Aircraft: PA-28 and PA-44 wing and fuselage sheet metal work.

• Commercial Aviation: Utilized in Boeing and Airbus cabin interior structures and non-pressurized secondary skins.

The Cherry Aerospace CR3242-4-1 is the definitive structural fastener for thin-gauge aerospace sheet metal repair. When a standard 1/8" rivet hole is worn or oversized, this 1/64" oversize rivet allows you to clean the hole with a #27 drill and restore a factory-strength interference fit. Engineered with a NAS1097 reduced flush head, it is the ideal choice for exterior skins where aerodynamic smoothness and fatigue resistance are paramount. With the reliability of an 8740 steel stem and a permanent mechanical lock, the CR3242-4-1 provides a professional, airworthy finish for high-performance aircraft maintenance.

Installation & Maintenance Addendum

1. Hole Prep: Use a #27 Cobalt Drill Bit. A standard #30 bit is too small for this oversize shank and will cause the rivet sleeve to jam or gall during insertion.

2. Grip Range Check: This is a "short" rivet. If your total material thickness exceeds 0.062" (1/16"), you must step up to a -2 or -3 grip length to ensure proper blind-side bulbing.

3. Tooling: Compatible with Cherry G704B, G747, or the G29 hand tool. Always ensure the pulling head is clean and properly adjusted to shear the locking collar at the correct tension.

Product Specification: