CR3212-4-04 – CherryMAX® Blind Rivet (Nominal)
Part Number: CR3212-4-04
Manufacturer: Cherry Aerospace (A PCC Company)
Military Specification: NAS1400 / MIL-R-7885
Overview Section
The CR3212-4-04 is a high-performance structural blind rivet featuring a universal (protruding) head. As a core member of the CherryMAX® family, it is engineered to provide the structural integrity of a solid "AD" rivet in applications where access to the backside of the work is restricted.
The "3212" series is the Nominal Diameter version, featuring a standard 1/8" shank. It is the industry-standard fastener for airframe assembly and repair, utilized extensively for attaching skins to ribs, stringers, and bulkheads. The CherryMAX system is distinguished by its "Safe-Lock" mechanical locking collar, which ensures the stem is permanently retained to provide maximum shear strength.
Enhanced Technical Data
| Technical Metric | Specification Data |
| Nominal Diameter | 1/8 in (Size -4) |
| Actual Shank Diameter | 0.125 in – 0.128 in |
| Grip Range (-04) | 0.188 in – 0.250 in (3/16" to 1/4") |
| Head Style | Universal Head (Protruding) |
| 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) |
| Finish | Chemical Film (Sleeve) / Cadmium Plate (Stem) |
| Required Hole Size | #30 Drill Bit (0.129" – 0.132") |
Advanced Engineering & Structural Application
The CR3212-4-04 is designed for High-Vibration Structural Joints. In aerospace engineering, the primary concern with blind fasteners is the potential for the "mandrel" or stem to fall out over time. The CherryMAX system solves this through a mechanically locked spindle.
Engineering Insight: The Bulbed Head Formation
During the installation cycle, the sleeve undergoes controlled deformation to form a large "bulb" on the blind side.5 This provides a broad bearing surface that resists "pull-through" failures, even in thin-gauge materials.6 Because the stem remains locked inside the sleeve, it essentially creates a solid metal plug that fills the hole, preventing fluid migration and enhancing the fatigue life of the airframe.
Materials Science
The use of 5056 Aluminum for the sleeve offers excellent corrosion resistance and compatibility with most aircraft aluminum skins (2024 or 7075). The 8740 Alloy Steel stem is heat-treated to ensure the rivet maintains its shear strength under the cyclic loading of flight.
Aircraft Compatibility
The CR3212-4-04 is a staple in the Structural Repair Manuals (SRM) of virtually all metallic aircraft:
Textron Aviation: Standard for non-flush skin repairs on Cessna 172/182 and Beechcraft King Air.
Piper Aircraft: Extensively used in the PA-28 and PA-32 series for internal structural patches.
Bombardier: Utilized in regional jets (CRJ) and business jets (Challenger) for secondary structure assembly.
Experimental Aircraft: The preferred fastener for Van's RV builders for "blind" sections of the fuselage and wing.
The Cherry Aerospace CR3212-4-04 is the definitive structural fastener for airframe technicians who demand uncompromising reliability. Designed for a grip range of .188" to .250", this nominal 1/8" rivet ensures a perfect interference fit in standard #30 holes.7 By utilizing the CherryMAX Safe-Lock system, this fastener provides the high-shear performance of a solid rivet with the convenience of blind-side installation. Whether you are performing a skin repair on a Cessna or maintaining a fleet of commercial jets, the CR3212-4-04 delivers a permanent, mechanically locked finish that meets the most stringent aviation safety standards.8
Installation & Maintenance Addendum
Hole Precision: Use a high-quality #30 Cobalt Drill Bit. Ensure the hole is deburred; any shavings between the sheets will prevent the rivet from pulling the layers tight together.9
Grip Length Verification: Use a Grip Gauge to measure the total material stack-up. For the -04 grip, your total thickness must be between 3/16" and 1/4".
Tooling: Compatible with Cherry G704B, G747, or the G29 hand tool. Verify that the gold locking collar is visible in the rivet head after the stem fractures to ensure a positive lock.
CR3212-4-04 FEATURES
| Parameter | Characteristics | ||
| Fastener Length | : | 0.339" inches minimum and 0.359" inches maximum | |
| Head Style | : | Flush (flat) countersunk (included angle - less than 135 deg W or W/O chamfer) | |
| Shank Diameter | : | 0.125" inches minimum and 0.129" inches maximum | |
| Shank Style | : | Self-plugging mechanically locked stem | |
| Head Major Diameter | : | 0.229" inches maximum | |
| Expansion Device | : | Serrated stem-type W | |
| Grip Length | : | 0.188" inches minimum and 0.250" inches maximum | |
| Countersink Angle | : | 99.0 degrees minimum and 101.0 degrees maximum | |
| Special Features | : | Ns" letters after the material code "b" indicate no preference to lock type (may be visible or internal). rivets with no letter code (indicating visible lock type) and rivets with the letter "h" after the material code (indicating internal lock type) are both acceptable for this item of supply. | |
| Material | : | Aluminum alloy 5056 sleeve | |
| Material | : | Steel comp 8740 stem | |
| Material Document and Classification | : | Ams 6322 assn std single material response stem | |
| Material Document and Classification | : | QQ-A-430 fed spec single material response sleeve | |
| Surface Treatment | : | Cadmium stem and chromate stem | |
| Surface Treatment | : | Chromate sleeve | |
| Surface Treatment Document and Classification | : | MIL-C-5541 mil spec single treatment response sleeve | |
| Surface Treatment Document and Classification | : | QQ-P-416 ty 2 cl 2 fed spec single treatment response stem |
This part is used on the following aircraft:
- • Textron Aviation Beechcraft King Air 200 - all variants
- • Textron Aviation Beechcraft King Air 300 - all variants
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