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NAS397-18 – Ratcheting Hose Clamp
Available now on the Airparts.aero Marketplace.
Overview
The NAS397-18 is a National Aerospace Standard, single-use, ratcheting hose clamp designed for securing low-pressure hoses and wire bundles in a variety of aerospace applications. Unlike traditional worm-gear clamps, the NAS397 is made from a lightweight, high-strength polymer and features a unique toothed, interlocking design that provides a secure, tamper-proof, and vibration-resistant hold once installed. This clamp is engineered for speed of installation and reliability, making it a preferred choice for modern airframe and systems manufacturing where weight savings and consistent clamping force are critical.
Key Features
- Lightweight Polymer Construction: Manufactured from a high-quality, durable nylon (or similar aerospace-grade polymer). This material offers significant weight savings compared to metal clamps and is inherently resistant to corrosion and most aviation fluids.
- Self-Locking Ratchet Design: Features a unique "double-row" tooth design that allows the clamp to be progressively tightened. Once the teeth engage past a certain point, the clamp is permanently locked and cannot be loosened or removed without being destroyed, ensuring a tamper-proof connection.
- Vibration Resistance: The positive-locking ratchet mechanism is extremely resistant to loosening under the constant vibration found in aircraft, providing a more reliable hold than many traditional clamp types.
- Controlled Clamping Force: Designed to be installed with a specific hand tool (e.g., NAS398 series pliers) that ensures a consistent and proper clamping pressure is applied every time, preventing over-tightening and damage to the hose or underlying components.
- NAS Certified Standard: Manufactured in strict accordance with the National Aerospace Standard, guaranteeing material quality, dimensional accuracy, and performance characteristics for certified aviation use.
Technical Specifications
- Standard: NAS397
- Full Part Number: NAS397-18
- Component Type: Single-Use Ratcheting Hose Clamp
- Material: Nylon (Polymer)
- Color: Typically Natural (White/Off-White) or Black
- Nominal Clamp Diameter: 1-1/8 inches (1.125 inches)
- Installation Tool Requirement: NAS398 series installation pliers
- Temperature Range: Varies by specific material, but typically suitable for standard airframe and cabin environments.
Aircraft Compatibility
The NAS397-18 clamp is a universal component not specific to a single aircraft model. It is widely used in modern commercial, military, and general aviation aircraft, particularly in areas where low-pressure fluid lines, wire harnesses, or ducts need to be secured.
- Common Applications:
- Drain & Vent Lines: Securing low-pressure fluid drain and vent hoses.
- Wire Harness Bundling: Used as a heavy-duty, permanent strap for securing wire bundles to airframe structures.
- Conduit & Tubing: Fastening flexible conduit, SCAT tubing, and insulation blankets.
- Avionics & Cabin Systems: Securing components and wiring for cabin pressurization, environmental control systems, and avionics cooling ducts.
Applications
The NAS397-18 clamp is the ideal solution for specific, permanent installations:
- Low-Pressure Fluid Lines: Perfectly suited for securing hoses in systems where internal pressure is minimal, such as pitot-static system drain lines or air-conditioning condensate drains.
- Permanent Wire Management: Offers a stronger, wider, and more secure alternative to standard cable ties for critical wire bundle installations that are not intended to be serviced regularly.
- Non-Metallic Connections: Being non-conductive and non-corrosive, it is ideal for use with composite structures and in areas where preventing galvanic corrosion is important.
Why Choose NAS397-18?
For permanent, low-pressure installations, the NAS397-18 clamp offers a superior combination of light weight, speed of installation, and vibration-proof security. Its tamper-proof design ensures that a critical connection cannot be accidentally loosened or reused. By using a certified NAS component, you are ensuring that the clamp meets the flammability, temperature, and strength requirements for aviation use, a guarantee that commercial-grade hardware cannot provide. For production environments and certified repairs, it is the modern, engineered solution for permanent clamping needs.
Order Your NAS397-18 Clamps Now
Secure your aircraft's systems with certified, lightweight, and reliable hardware. Visit Airparts.aero to order your NAS397-18 ratcheting hose clamps today.
The engineering principle behind the NAS397 clamp is to provide a "fit and forget" fastening solution. The double-row toothed band and the pawl within the clamp head create an irreversible ratchet. As the clamp is tightened with the NAS398 pliers, the teeth slide over the pawl. Once the pliers are released, the pawl securely engages the teeth, preventing the band from backing out. This design provides a consistent, pre-determined tension that is dependent on the installation tool, not the operator's "feel." This level of process control is highly desirable in aerospace manufacturing. Furthermore, its broad, smooth band distributes the clamping force over a wider area than a traditional cable tie, reducing the risk of pinching or damaging wires, insulation, or lightweight composite tubing.
NOTES
ORDER AS FOLLOWS: S1891-12 CLAMP CLAMPING RANGE IS MIN.-.69 AND MAX.-1.25 OR S1891-20 CLAMP CLAMPING RANGE IS MIN.-.81 AND MAX.-1.75 OR S1891-20S CLAMP SAME AS -20 BUT IT IS STAINLESS STEEL OR S1891-24 CLAMP CLAMPING RANGE IS MIN.-1.06 AND MAX.-2.00 S1891-24S S/A -24 BUT IS STAINLESS STEEL
Applicable Textron Aircraft
- Baron Series B55, E55, 58 or G58
- Bonanza F33, G33, F33A or F33C
- King Air 100
List not comprehensive, may be applicable on other models.
Other Textron Notes:
- ACCEPTABLE ALTERNATE FOR BEECH APPLICATIONS
A3122-18-1J - ACCEPTABLE ALTERNATE FOR BEECH APPLICATIONS
MS22064-5 - MODEL RESTRICTED - SEE COMMENTS
S1891-12 - MODEL RESTRICTED - SEE COMMENTS
S1891-20 - MODEL RESTRICTED - SEE COMMENTS
S1891-20S - MODEL RESTRICTED - SEE COMMENTS
S1891-24 - MODEL RESTRICTED - SEE COMMENTS
S1891-24S
Note: This is a single-use clamp. Once fully engaged, it cannot be removed without cutting the band, which destroys the clamp. It must be installed using the correct, specified NAS398 series installation tool to ensure proper tensioning and locking. Do not use for high-pressure fluid applications.
