Ask a rigger | How much webbing wear can there be at the harness hip ring before the webbing has to be repaired or replaced?
By Kevin Gibson
Like just about any innovation or improvement, the hip rings introduced to make a skydiving harness more flexible for freestyle and freeflying have a downside. If the harness is fitted correctly so the two ends of the leg strap at the ring seldom or never make contact, no wear should appear. However, heavy friction at that point can lead to visible damage. Additionally, rubber stow bands on the hip rings, which jumpers often use to hold down shirttails etc., can cause abrasion, and in 2003, United Parachute Technologies issued a bulletin that warned jumpers not to use rubber stow bands this way.
The heavy wear on the hip-ring/leg-strap junction from an Infinity (shown in the upper right photograph) prompted an email to the manufacturer, Velocity Sports Equipment. A lot of differently sized students and new jumpers had been renting this rig with its 190-square-foot main canopy. There’s no telling what kind of angles at the hip junction may have led to contact between the two worn points.
Kelly Farrington, president of VSE, agreed to take a closer look. As one would expect of any manufacturer, Farrington performs a lot of testing on his equipment. He and his crew took this rig to a facility with a dynamometer—a device that pulls things apart and measures how much tension it takes to do so.
Brand new off the roll, the type-8 webbing used at the hip junction is rated for 4,000 pounds breaking strength. Everyone attending the test made $5 bets on how much force it would take to break the worn portion. These guesses ranged from 3,800 to 4,800 pounds, with the author’s outlier bet at 1,900 pounds.
On the first test, because of the way they rigged the harness to the machine, the edge of the thin chest-strap hardware worked its way through its webbing at 4,372 pounds. They then repositioned everything, but the leg strap adjustment hardware—although fat with a smooth edge—began grinding through its undamaged webbing at 4,066 pounds. The hip junction, even with its damaged webbing, held firm. They tried again. Ultimately, the webbing at the hip junction in question broke at 4,674 pounds. Farrington’s guess won the $20 pool, only 126 pounds low. So, there was never any question in the manufacturer’s mind about the effect of the wear on the overall strength of the harness. Even with the damage and the uneven loading, it failed above the 3,500 pounds for which the government tested and approved it.
In a casual conversation, Bill Booth at United Parachute Technologies reckoned that during a barely survivable hard opening, a harness would need to withstand only something in the neighborhood of 500 pounds. Farrington said possibly more if the harness loaded unevenly and took a lot of strain in only one area. But safe to say that this Infinity harness with its worn webbing would have held up for many more jumps.
Obviously, VSE’s test was as much for curiosity as for scientific research, and the rest of the rig was already trashed enough to remove from service. But the effort tells a story: Under all reasonable conditions of use and maintenance, skydiving harnesses will break under load long after the jumpers they’re built to carry. And that’s morbidly comforting.
However, a rigger presented with a harness showing the wear apparent in the first photo has to consider a number of issues. Few will have the equipment to test the harness, much less the understanding of the best way to engineer a meaningful test. A differing second opinion from another rigger down the line would just lead to even more doubt in the owner’s mind. And what about the instructor discovering it later when issuing the rig to a student? Or worse, a student discovering it and pointing it out to an unwitting instructor?
So, the decision to perform a repair of even several hundred dollars to a visibly worn harness isn’t out of the question for a system that otherwise has lots of jumps to go before retirement. Nor is retiring a system with lots of visible wear just for peace of mind for the rigger, the owner or for the image of the skydiving school. The job of your quintessential rigger in the field is to advise you of wear discovered during the routine 180-day inspection, help you avoid it and assist you in keeping your equipment to a high standard of maintenance. After all, besides your safety, the rigger’s reputation is on the line.
Kevin Gibson | D-6943 and FAA Designated Parachute Rigger Examiner
Rahlmo’s Rigging at Skydive Orange in Virginia