Soft Links vs. Regular Links

Tag: Ask a Rigger, Gear, March 2012

Q:

 

Should I get the fabric loop-style connector links or the steel ones to connect my canopy to the risers?

 

A:
Most jumpers should go with fabric or “soft” links on both the main and reserve. Of course, certain exceptions for a specific use might make the race-track-shaped steel links (aka “French” or “rapide” links) the better choice for you. Some people choose to go with what they know, and there’s nothing wrong with that—steel links have connected parachutes to harnesses for years. However, soft links have been in use for long enough now to have proven themselves to be the best choice for most skydiving purposes.

Although canopy manufacturer Performance Designs is not the first or only company to offer a fabric loop or fabric-metal combination alternative to steel connector links, it dominates the market with its Slink® brand of all-fabric link. PD offers one version for mains and a beefier, FAA-approved version for reserves. There’s no metal involved in either version’s construction or assembly.

Before going to market, PD intentionally tested systems—both steel and Slink®—to the failure point. In its literature, the company reports that Slinks® performed well while suspension lines broke or 3-ring systems failed. PD preferred the performance of Slinks® over the steel links, which distorted or failed altogether when overloaded.

At first, many jumpers took a wait-and-see attitude as fabric links became available. By the time the FAA approved PD’s reserve model of Slinks®, soft links had already been around in one form or another for at least three decades without scaring skydivers away. Even at a little over $25 per set, they’re cheaper than either the steel or stainless-steel French links they displace. Getting whacked on the knuckles or head with French links during opening (not to mention what they can do to expensive cameras and helmets) helps jumpers appreciate all-fabric links even more.

Steel links come with other liabilities. Riggers and industry experts agree that the only brand suitable for parachute connector links carries the marking “Mallion Rapide” (which come from France—hence the term “French” link), not the generic alternatives found on the shelf at various hardware stores. There is a specification for the number of inch-pound or Newton-meters of torque for tightening steel links, which generally translates in actual use to “finger tight (maximum thread engagement) plus a quarter turn with a wrench.” Cheap knock-offs have been known to fail on assembly, either turning past the point of maximum thread engagement or having the threaded barrel crack. Even Mallion Rapides® aren’t perfect. The barrels have been known to crack from over-tightening, and they sometimes have sharp edges and burrs that need to be addressed before they snag suspension lines.

Sometimes, steel links randomly disassemble themselves. Too many inattentive jumpers have landed with one of their French links bent wide open and the lines literally hanging on by a thread. A drop of liquid thread locker (for example, Loctite® brand) on the threaded barrel nut where it meets the shank can prevent the barrel from turning. Many tandem mains still use French links, so vigilance is important on these systems. (PD Slinks® proved incompatible with the control line, slider and brake systems of some tandem main parachute systems, so steel links remain the norm on those.)

Most parachutes without a collapsible slider suffer from “motorboating,” where the slider flaps and flops in flight. Motorboating hammers the slider grommets against the connector links, with the suspension lines in between taking much of the abuse. Hammering against steel connector links can ruin the suspension lines in only a few jumps. Soft links make motorboating a non-issue.

Sliding a short length of flexible tubing, or “slider bumpers,” over steel links protects the lines from damage. The tubes also help keep the barrels from unthreading. However, tube-type slider bumpers become a maintenance headache of their own, requiring the packer to inspect and adjust them after every jump. They wear out from brake-line friction, and replacement requires disassembly, which calls for a rigger’s skills and tools. Fabric slider bumpers—just a wrap of webbing sewn into position—last longer than tubes but don’t protect as well or prevent the link from loosening.

Slider bumpers may be incompatible with the steel links used on tandem main systems. Tandem manufacturers use different methods to address the problems associated with the slider flapping.

On the other hand, after a correct assembly, soft links should require little or no maintenance beyond inspection. Some have even been misassembled and still performed their jobs. (See “Keep an Eye Out” in February’s Parachutist for an egregious example). Generally, all one needs to do is to spin the loop until the locking portion stays hidden inside the end of the riser. However, because soft links are nylon, jumpers should keep a close eye on them and replace them at the first signs of visible wear or if they find any damage. Slider grommets may have sharp edges or burrs that can quickly damage soft links (not to mention the suspension lines). At least one jumper has been severely injured when a worn out soft link went undetected and broke just before he landed, causing the canopy to spin him into the ground. Because there are so many factors that affect the lifespan of soft links, jumpers must inspect them frequently.

One advantage to soft links can be a disadvantage for some jumpers. Canopy pilots who like to pull their sliders down over the connector links and brake systems to the bottom of the risers will find it easier with soft links. Those who like the slider to stop and stay at the top of the risers may have to install a stopping device of some sort. PD provides optional slider stops for Slinks®.

Some day in the future, something may change that makes soft links impractical or obsolete. But at this point in the game, they’re a hands-down improvement over French links for most applications, which were a hands-down improvement over the big, bulky L-bar links they themselves replaced. That’s just the way our sport evolves.

Link progression, 1970 to present (from left to right): L-bar links, which are still used for some tandem reserves; Number 5 Mallion Rapide® links in steel and stainless steel, which are often found on reserves; Number 4 and 3.5 stainless steel links; PD Slink® for mains.
Assembly sequence of a PD Slink®: The length of the line goes through the connection twice, then the loop end passes below a small opening below the button head. Finally, the loop goes over the button head. PD provides optional instruction to tack the assembly for extra security.
PD main and reserve Slinks® fabric connector links, both after use.
Example of a fabric slider bumper installed on a French link.
Example of a plastic tubing slider bumper installed on a French link.
It's important to keep the fabric-link locking mechanism hidden inside the end of the riser. For PD Slinks® (shown here), instructions are provided for optional tacking to keep them in place and provide extra security.

—Kevin Gibson | D-6943
Master Rigger
Orange, Virginia

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