CR3242-4-03 – CherryMAX® Blind Flush Rivet (Oversize)
Part Number: CR3242-4-03
Manufacturer: Cherry Aerospace (A PCC Company)
Military Specification: NAS1097 / MIL-R-7885
Overview Section
The CR3242-4-03 is a high-strength oversize structural blind rivet featuring a 100° flush (countersunk) head.1 It is part of the world-renowned CherryMAX® family, recognized as the industry standard for high-reliability blind fastening.2 The "42" designation signifies the oversize diameter, engineered specifically for MRO (Maintenance, Repair, and Overhaul) applications where the original rivet hole has been enlarged, damaged, or cleaned of corrosion during the removal of a nominal 1/8" fastener.
With an actual shank diameter approximately 1/64" larger than standard, the CR3242-4-03 ensures a precision interference fit in reworked holes. This restores the load-bearing capacity of the airframe skin and internal structures while maintaining an aerodynamic flush profile.
Enhanced Technical Data
| Technical Metric | Specification Data |
| Nominal Diameter | 1/8 in |
| Actual Shank Diameter | 0.140 in – 0.143 in (Oversize) |
| Grip Range (-03) | 0.126 in – 0.187 in |
| Head Style | 100° Flush Head (Reduced Profile per NAS1097) |
| Ultimate Shear Strength | 530 lbs (minimum) |
| Ultimate Tensile Strength | 245 lbs (minimum) |
| Sleeve Material | 5056 Aluminum Alloy (AMS 4118) |
| Stem Material | 8740 Alloy Steel (AMS 6322) |
| Locking Collar Material | A-286 Corrosion Resistant Steel |
| Required Hole Size | #27 Drill Bit (0.144" – 0.147") |
Advanced Engineering & Structural Application
The CR3242-4-03 is designed for Structural Load Path Restoration. In aerospace structures, a loose or "smoking" rivet compromises the aircraft's fatigue life. The oversize shank of the -42 series fills the void created by hole wear, preventing "shuttling" (micro-movements) of the fastener.
Engineering Insight: The Bulbed Blind Head
During installation, the sleeve does not simply expand; it "bulbs" against the blind side of the structure.3 This creates a large, uniform bearing surface that distributes the clamping force over a wider area. This is particularly advantageous when fastening thin skins to heavier internal frames, as it prevents the rivet from pulling through the skin under high tensile loads.
Mechanical Safe-Locking Spindle
The hallmark of the CherryMAX system is the Integral Driving Anvil and Locking Collar.4 As the tool reaches the final pull stage, it drives the collar into the stem's locking groove. This ensures the stem is permanently retained, contributing its high-shear steel strength to the overall joint, unlike "pop" rivets where the mandrel is lost or non-structural.
Aircraft Compatibility
The CR3242-4-03 is ubiquitous in the Structural Repair Manuals (SRM) of virtually all metallic aircraft:
Textron Aviation: Essential for Cessna Citation and King Air skin-to-rib repairs.
Bombardier: Extensively used in the CRJ and Challenger series secondary structures.
Gulfstream: Found in cabin pressurized bulkheads and floor structures.
General Aviation: The "gold standard" for repairing loose 1/8" rivets on Piper, Beech, and Mooney airframes.
The Cherry Aerospace CR3242-4-03 provides a critical engineering solution for airframe technicians. When a standard 1/8" rivet hole becomes oversized due to vibration or repair work, the CR3242-4-03 restores the original structural integrity of the joint. With a grip range specifically suited for material thicknesses between 1/8" and 3/16", this fastener combines the aerodynamic superiority of a NAS1097 flush head with the shear-load capacity of an 8740 alloy steel stem. The CherryMAX "Safe-Lock" system ensures that the stem stays put, providing peace of mind for pressurized cabins and high-stress airframe components.7
Installation & Maintenance Addendum
Hole Size Warning: Do not attempt to install this rivet in a standard #30 hole. It requires a #27 drill bit.
Tool Compatibility: Compatible with standard power and manual pulling tools, including the Cherry G704B, G747, and the G29 hand riveter. Ensure the pulling head is a dedicated CherryMAX type (e.g., H701-456).
Visual Confirmation: A correctly installed CR3242-4-03 will show the gold locking collar seated flush with the rivet head. If the stem breaks off below the head surface and the collar is missing, the rivet has not locked and must be replaced.