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Rigging: Closing Loops

Reprinted from the July 2009 issue of Blue Skies Mag

By Mike Gruwell

Hidden behind flaps, under grommets and inside your container are tiny pieces of metal that can end your Sky God status in a hurry. In an ideal world, all the metal in skydiving is polished, shiny and smooth as silk. But manufacturing issues, abnormal wear and just plain sharp edges can lead to frayed and broken loops in your main and reserve container. The inspection is easy; a little bit of time and some basic knowledge on what to look for will go a long way in keeping your container closed when you need it to be. You can also save yourself from having to constantly replace your loops.

The majority of main closing loops are set and anchored through a washer, which then rests against a grommet. Behind the washer are knots in your loop. The first hidden sharp edge to check for is in the washer itself. It may be smooth on one side, but it can be sharp on the other. Take the closing loop out of the washer and run your finger around the edge of the hole on both sides. Smooth the washer out with emory cloth if needed, or replace it with a washer that has no nicks.

Grommets in the main container are the next item to check. Start with the one in the main closing loop anchor, which may be separate from or part of the container flap. Just like the washer, run your finger over both sides of the grommet and into the hole, feeling and looking for sharp edges. Sharp edges are created by an improper “set” during manufacturing or from the high tension during closing, which can open a previously-set grommet. An industry-wide bulletin in the 1990s dealt with the outside edges of grommets not being set flush or into the fabric, which could then allow a line to catch on the grommet.

PIA Technical Bulletin TB-241: Container Grommets and Small Suspension Lines PIA Technical Bulletin TB-241: Container Grommets and Small Suspension Lines

SERVICE BULLETIN: # FSI-SB-1004: MAIN CONTAINER CLOSING GROMMETS SERVICE BULLETIN: # FSI-SB-1004: MAIN CONTAINER CLOSING GROMMETS

SERVICE BULLETIN: # FSI-SB-1005 rev (1): ALL CONTAINER GROMMETS SERVICE BULLETIN: # FSI-SB-1005 rev (1): ALL CONTAINER GROMMETS

01/13/2004: Grommet Inspections/Vigil Features

SERVICE BULLETIN # SPSB: 03032000 – Revision B: MAIN CLOSING LOOP RETAINER – Grommet Protection SERVICE BULLETIN # SPSB: 03032000 – Revision B: MAIN CLOSING LOOP RETAINER – Grommet Protection

Service Bulletin SPSB # 03032000 Revision B Service Bulletin SPSB # 03032000 Revision B

08/08/2004: “Recent stabilizer, grommet, cable and closing loop inspection issues”

But there are also wear issues with grommets where the inside edge rolls onto the opposing side of the grommet. This edge, if unseated, won’t necessarily catch a line, but it will cut and damage loops. Fixing this usually entails your rigger or container manufacturer resetting the grommet back to its original shape/setting with a grommet inserting die. If resetting the grommet doesn’t remove the sharp edge, then your rigger should replace the grommet entirely.

Grommets in the reserve container have the same issues, and are more likely to distort their shape or pop-up slightly and expose a sharp edge. This is due to the high tension on the closing sequence for most sport reserve containers. Riggers check each grommet during an inspection and repack for exposed sharp edges. A sharp grommet edge can nick and completely cut a reserve closing loop during closing when a flap is brought into place over the closing loop. Any sharp edge, combined with the tensioned loop, can lead to a spring-loaded pilot chute in the face and/or fraying of the loop. A frayed loop has lost strength, and must be replaced.

Just like a sharp edge on a main closing loop washer, a rigger can encounter a sharp edge on a reserve closing loop washer. Checking for nicks or rough spots before threading a new loop through the washer will prevent unexpected damage later. Riggers should also check the closing loop anchor grommet(s) for sharp edges.

One other culprit for a frayed or broken reserve closing loop is a nicked or rough temporary pin. The temporary pin is inserted in the closing loop after each successive flap is pinned. If that pin is not smooth, the high tension of the loop combined with the rough pin will damage the loop immediately.

So, jumpers and riggers–check those loops, washers and grommets. Smooth out the rough edges or replace them if needed.

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