?unique=3fa7b7d)
PE21101-3-2CP – Passivated Stainless Steel Sheet Metal Screw
Available now through the AirParts Aero marketplace.
Overview Section
The PE21101-3-2CP is a high-grade Stainless Steel Sheet Metal Screw specifically engineered for aerospace and marine environments where corrosion resistance and structural integrity are paramount. This fastener features a #10 diameter with a #10-32 UNF thread pitch, bridging the gap between a standard tapping screw and a machine screw for use in specialized nut plates or thin-gauge tapped extrusions.
Constructed from premium stainless steel and subjected to a chemical Passivation (CP) process, this screw is designed to resist "tea staining" and galvanic corrosion when used in aluminum airframes. The 15/32-inch length is optimized for securing cowlings, inspection plates, and interior fairings where a standard 1/2-inch screw might interfere with internal structural members.
Key Features Section
Passivated 300-Series Stainless Steel: Undergoes a chemical bath that removes free iron from the surface, enhancing the natural chromium-oxide protective layer for maximum rust resistance.
Precision #10-32 UNF Threads: Provides a fine thread count that offers superior vibration resistance and higher clamping force compared to coarse-threaded hardware.
High-Torque Drive Head: Designed to be driven with standard aerospace tools, minimizing the risk of head stripping or "cam-out" during high-frequency maintenance cycles.
Flat/Countersunk Profile: Often utilized in aerodynamic "flush-mount" applications to maintain laminar flow across exterior skins.
Environmental Stability: Resistant to aviation fluids, including Jet-A, Skydrol, and cleaning solvents, ensuring the fastener remains removable after years of service.
OEM Certified Compatibility: Manufactured to meet the specific "PE" (Private Enterprise/Proprietary) standards often found in Textron Aviation and Piper Aircraft assembly manuals.
Technical Specifications Section
| Specification | Detail |
| Part Number | PE21101-3-2CP |
| Thread Size | #10-32 UNF |
| Screw Diameter | #10 (0.190 in) |
| Length | 15/32 in (0.468 in) |
| Material | Stainless Steel |
| Finish | Passivated (CP) |
| Head Style | Countersunk (Typical for PE21101 series) |
| Drive Type | Phillips or Tri-Wing (Check specific lot) |
Aircraft Compatibility Section
The PE21101-3-2CP is a foundational fastener used extensively in light and mid-size aircraft:
Cessna 100/200 Series: Used for securing inspection panels on the underside of wings and fuselage.
Piper Cherokee/Archer/Saratoga: Found in interior trim and cabin plastic window molding attachments.
Beechcraft Bonanza: Utilized for secondary fairing attachments and cooling shroud mounts.
Cirrus SR20/SR22: Often used in non-structural composite-to-metal bonding interfaces.
Technical Applications & Safety
Fasteners in the PE21101 series are designed for "Serviceability." In aviation, a stuck or rusted screw can lead to hours of "drill-out" time.3 By using passivated stainless steel, the PE21101-3-2CP ensures that the fastener can be removed easily during the next 100-hour or Annual inspection.
Safety Warning: Do not over-torque in composite materials. While the #10-32 thread provides high clamping force, over-tightening into nut plates attached to fiberglass or carbon fiber can lead to "delamination" around the fastener hole. Additionally, always verify that the Countersink Angle of the screw matches the dimple in the sheet metal; a mismatch will cause the head to sit proud of the skin, increasing drag and creating a potential snag point for maintenance rags or clothing.
Technical Engineering Insight
The engineering value of the PE21101-3-2CP lies in its Galvanic Compatibility. When a standard steel screw is placed in an aluminum wing skin, the two dissimilar metals create a "battery" effect in the presence of moisture, leading to rapid corrosion of the aluminum.4 The Passivation (CP) on this 300-series stainless screw creates a non-reactive barrier that significantly slows this electrochemical process.5 This is particularly vital in the 15/32-inch length, as this size is frequently used on the lower fuselage where moisture and salt-laden "run-off" tend to collect.
Installation & Maintenance Addendum
Anti-Seize Usage: While passivated, it is still recommended to use a tiny amount of Tef-Gel or high-temperature anti-seize when installing these screws into stainless steel nut plates to prevent "galling" (cold welding).
Dimple Inspection: Before installation, ensure the sheet metal dimple is clean. Debris trapped under the countersunk head of a PE21101-3-2CP will prevent a flush fit and lead to localized stress skin cracking.
Driver Fit: Ensure your Phillips #2 or specialized driver is in good condition. Stainless steel is softer than alloy steel; a worn driver bit will "round out" the head of the screw almost instantly.
