In the past three months, there have been two incidents involving older paraglider harnesses equipped with CLICK-LOCK buckles (HSi10) in the chest strap. The buckles had opened unintentionally during flight while they were under load. In one of the cases this happened during a SAT maneuver (spreading of the chest strap due to the pilot resting on the riser), in the other case the reason was presumably the load applied by the body weight of the pilot who was hanging only in the leg straps.
Finsterwalder has conducted a technical investigation and found the following: The hooks of the metal tongue can wear out through the frequent diagonal load changes the chest strap is subject to. This might lead to decreased load capacity and – in the case of sufficiently high diagonal load transmission – the buckle might open unintentionally.
As a consequence of this finding, Finsterwalder has limited the respective buckles’ service time to 4 years if they are used in paraglider chest straps. The harness manufacturers have already been informed accordingly.
To date, there have been no unintentional openings of T-LOCK buckles. However, since their mechanism resembles that of CLICK-LOCK buckles, the problem is likely to be the same.
Finsterwalder calls on all owners of harnesses equipped with CLICK-LOCKs (HSi10) or T-LOCKs in the chest strap to determine their buckles’ previous usage time by checking the routine test date on the sample inspection label. If this date indicates a usage time of more than 4 years, the harness is not airworthy for now and may not be used for flying anymore. Affected owners should contact their harness manufacturer.
The service time limitation applies only to CLICK-LOCK and T-LOCK buckles that are used in paraglider chest straps. When used for applications where only static loads are involved, the CLICK-LOCK and T-LOCK buckles’ service life is 10 years.
The following harness manufacturers have used the mentioned buckles in one or more of their models: Advance, AVA Sport, APCO, Finsterwalder & Charly, KARPO FLY, SKY Paragliders, SkyTrekking, SOL, Woody Valley. Besides the buckles are used in paramotor harnesses of several manufacturers.