ISO 21894:2020 pdf free.Air cargo – Cargo stopper devices – Design and testing.
3.1 breaking force BF lowest load at which a unit under tensile test exhibits part or complete failure
Note 1 to entry: Deformations are not accounted as a failure.
3.2 interlinking straps cargo stopper straps sewn at an angle with the tension straps (3A), forming a web to adapt the shape of the piece of cargo but which do not transmit the in-flight loads, to which they are perpendicular
3.3 ‘piercing” cargo piece of cargo of a piercing or penetrating nature, such as rods, pipes, extrusions, beams, etc., that could become a projectile under flight operational loads
3.4 tension straps
cargo stopper straps which attach to the pallet through other straps or slings, and transmit in-flight loads, with which they form a low angle
4 Requirements
4.1 Cargo stopper devices (see typical examples in Figure 1) shall be built from sewn lengths of cargo restraint straps grade webbing, performing two different roles:
a) tension straps connecting to the main restraint arrangement straps and able to withstand the same forces;
b) interlinking straps forming a web like structure in order to prevent passage of small cross-section items, stitched together with supplemental continuous flexible material to fill the gaps between tension straps.
4.2 The tension straps shall consist of a single uninterrupted piece of webbing with a rated tension load of at least 22 250 N (5 000 lbf), consistent with that mostly used to manufacture cargo restraint straps. They shall meet the ISO 16049-1 design requirements applicable to the webbing and stitching.
4.3 The tension straps shall he equipped at each end with fittings allowing their attachment to standard cargo restraint straps per ISO 16049-1, or to pallet net rope as appropriate. The fittings may be hooks, rings or D rings, tie-down fittings or pieces of tie-down track, or a combination thereof. No tension device is required.
4.3.1 Hooks shall be equipped with a retainer and strong enough to withstand the rated load without deformation.
4.3.2 Rings or D rings shall be strong enough to withstand the rated load without deformation. Open rings or open D rings are not permitted. Any gaps in bent wire shall be welded to provide an uninterrupted circumference.
4.3.3 Tie-down fittings where used shall be of the double stud type and conform to the requirements of ISO 9788.
4.3.4 Tie-down track where used shall conform to the requirements of Iso 7166.
4.4 The interlinking straps may be of lesser grade webbing for flexibility, but their assembly shall ensure the total rated tension load of at least 22 250 N (5 000 lbf) between two opposite end fittings. Their geometric arrangement shall form a web ensuring the largest empty space between straps does not exceed a 100 mm (4,0 in) diameter circle. They shall be stitched together and with the tension straps at intersections. Webbing and stitching of tension straps and interlinking straps shall meet the applicable ISO 16049-1 design requirements.
4.5 The total area covered by the web of restraining straps shall Le at least more than a typical pallet net’s mesh size, i.e. 300 x 300 mm (12 x 12 in) diamond [400 x 400 mm (16 x 16 in) square], thus a minimum of 1 600 cm2 (250 sq.in). It is recommended to consider total areas up to 4 800 cm2 (750 sq. in), usually limited by the desired unit’s weight and flexibility to adapt to various shapes of cargo. See Figure 1 for examples.ISO 21894 pdf download.