ISO 20291-1:2021

Overview

ISO 20291-1:2021 is an international standard developed by the International Organization for Standardization (ISO) that specifies design and testing requirements for air cargo restraint sling assemblies made of steel wire rope. These restraint slings are critical equipment for securing cargo on board civil transport aircraft during flight, ensuring safety and operational reliability. The document outlines the criteria necessary to guarantee the ultimate strength and dependability of restraint sling assemblies with a rated ultimate load capacity of 22.25 kN (5,000 lbf), intended exclusively for restraint - not for lifting purposes.

Key Topics

• Types of Restraint Slings:

  • Type A: Adjustable length restraint sling assemblies, equipped with a tension retaining device and termination fittings.
  • Type B: Fixed length restraint sling extensions used in conjunction with Type A cables, typically with end eyes for connection.

• Design Criteria:

  • Construction using steel wire rope meeting stringent strength and flexibility requirements.
  • Use of corrosion-resistant materials and proper end fittings, such as hooks or double stud tie-downs.
  • Protective measures for operator safety and prevention of accidental disengagement.

• Testing Methods:

  • Comprehensive strength and function testing using calibrated tensile testing equipment.
  • Specific procedures, including sleeves tests, ultimate load and elongation tests, and cyclic load testing, to verify performance across all load scenarios in flight.

• Operational Considerations:

  • Use in various aircraft cargo restraint scenarios, from loaded airworthiness-approved pallets to individual cargo pieces and “floating” pallets.
  • Compatibility with aircraft-approved structural attachment points or pallet systems.

Applications

Air cargo restraint slings are essential tools for the airline industry and ground handling operations, ensuring secure transportation of goods via civil aircraft. Main applications include:

• Securing cargo on pallets: Restraint slings are used to tie down cargo on airworthiness-approved air cargo pallets that are then anchored within the aircraft’s cargo system.
• Direct restraint for unpalletized items: For non-unitized pieces of cargo or cargo placed on unrestrained pallets, slings provide a reliable means of securing loads directly to aircraft structure attachment points.
• Adaptability for different decks: Suitable for use on lower deck, main deck, or upper deck systems in accordance with relevant air cargo requirements.
• Replacement for straps: Where cargo straps’ elongation under tension is undesirable (e.g., heavy vehicles, aircraft engine stands, or machinery), steel wire rope slings offer minimal elongation and enhanced safety.

Organizations that benefit from adhering to this standard include airline operators, freight forwarders, ground service providers, air cargo handlers, and manufacturing companies supplying air cargo hardware.

Related Standards

Compliance with ISO 20291-1:2021 often requires consideration of other essential air cargo equipment and safety standards, including:

• ISO 8097: Minimum airworthiness requirements and test conditions for certified air cargo unit load devices (ULDs).
• ISO 21100: Performance requirements and test parameters for air cargo unit load devices.
• ISO 2408: Requirements for steel wire rope construction and performance.
• ISO 4117: Specifications for air and air/land cargo pallets.
• ISO 9788: Design and testing requirements for air cargo double stud tie-down fittings.
• ISO 7531, ISO 7597, ISO 8793, ISO 8794: Specifications for wire rope slings, hooks, and terminations relevant to air cargo restraint applications.

Following ISO 20291-1:2021 enhances in-flight safety, demonstrates compliance with internationally recognized best practices, and supports efficient, secure, and reliable air cargo operations.