Tuesday, December 11, 2018

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Ask a Rigger | Bottoms Up

By Kevin Gibson

Ask A Rigger | December 2018

Q: Some rigs have the main bridle routed top to bottom over the closing flaps, and some rigs have bridles that come out from underneath the closing pin and then back down the same direction. Which is more correct?

A: “More correct” is exactly the way to ask and answer this question. Until around 2010, almost all owners manuals called for the bridle to exit from underneath the top of the right-side closing flaps before insertion of the closing pin and then tuck back underneath at the bottom on its way to the pilot chute pouch. One exception was the Parachute Laboratories Racer, whose bridle has always come from under the bottom to the pin and back the same way.

In 2009, likely due to some subtle design and material changes to bridles and configurations of pin covers, jumpers began reporting instances of deploying a pilot chute and having the end of the curved pin somehow pierce the bridle and lock the container hopelessly closed with the pilot chute in tow. It occurred on various brands of rigs and was a bit of a mystery. One of the manufacturers, United Parachute Technologies, reported trying many times to recreate the problem but could not.

A number of articles appeared here and there with ideas on how to prevent the malfunction by twisting the bridle this way or that. But the designs and materials used in this area differ greatly from rig to rig. Frankly, nobody ever stepped forward with a clear explanation. The cause could be a combination of factors, including the way the pin is attached to the bridle, the material used to make the bridle, the direction the packer orients the pin, the length of the closing loop and even the size of the pin-cover flap.

Many manufacturers and riggers simply told jumpers to route their bridles more carefully to avoid contact with the end of the pin. United Parachute Technologies reverted to a prior design for attaching the pin to the bridle and also provided an alternate method of routing the pin (from under the bottom of the side flap, up to the pin and then back the same way—bottoms up).

Eventually, UPT made this its preferred method—the old way was omitted from the manual—and modified the bridle so that the inspection window for the inner bridle (that you check to make sure the pilot chute is cocked) is easier to see. Other manufacturers started exploring the alternative bottoms-up routing, as well. Required, recommended, allowed or disallowed, the bottoms-up routing began occurring on more and more rigs.

Done correctly, routing from the bottom up makes it pretty much impossible for the bridle to contact the end of the pin. However, the transition isn’t 100 percent complete. Some manufacturers have yet to fully settle on the bottoms-up routing.

The slow adoption has led some packers to MacGyver existing systems in search of a way to twist the bridle so the inspection window still shows during a pin check. Done improperly, that can leave the bridle still susceptible to malfunction and might even make it more so. The manufacturer of Wings, for example, has identified three instances of a pilot chute in tow with the bottoms-up routing, the result of the pin working its way into the inspection window. So, Sunrise Manufacturing does not recommend the bottoms-up routing for its Wings system.

Wings isn’t a complete outlier. The bottoms-up routing might not be the best solution for rigs with pin-cover flaps that tuck under, either. The extra bulk of the doubled-back bridle can reduce the effectiveness of the pin cover. For that reason, Velocity Sports Equipment prefers the conventional routing published in its current manual. Also, certain configurations on various rigs make it a little harder to fully hide the bridle when trying to route it bottoms-up.

Besides Racer, the UPT Vector is now packed exclusively bottoms-up. So is the Peregrine Glide. The latest manuals for the Aerodyne Research Icon, Firebird EVO, Mirage, Rigging Innovations Curv and Sun Path Javelin show it as an alternative method. But the situation is evolving, so it would be wise to stay abreast of the current manual and refer to yours for any rig not mentioned.

The best news is that attention to the problem seems to have all but eliminated this malfunction. Funny how we went for years without seeing it and then suddenly a rash of them occurred. Historically speaking, stuff like this pops up from time to time. It’s always good to stay current on your malfunction procedures just in case you’re the next jumper to make a new discovery.

Kevin Gibson | D-6943 and FAA Master Rigger
Rahlmo’s Rigging in Orange, Virginia

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