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## Square Canopy—Trim Check and Re-trim 

• Applicable products: Square main canopies 

• Description: Re-trimming the suspension lines of main canopies to return to the original trim specs 

• Authorized repairmen: FAA Senior or Master Parachute Rigger 

• Materials: E thread 

• Machines: 308 zigzag—medium duty 7–11 SPI or 1 inch × 42 stitch bar tack (optional) 

• Equipment: Scissors, seam ripper or scalpel, marking pencil, 6-inch ruler, 25-foot tape measure, and pony clamp 

## Procedure 

Checking and re-trimming main canopies is a common requirement for riggers. All canopies and all kinds of suspension lines get out of trim in time with use. The rigger that knows how to quickly check the trim on a customer’s canopy, and then determine how much work it takes to return it to the original configuration is performing a valuable service. In most cases, as long as the suspension lines are in good condition, re-trimming a canopy adds hundreds of jumps to the life of the canopy and returns the performance to almost as good as new. The chart shown in Figure A  is tailored to apply to normal ram-air canopies. Certain designs, 

such as elliptical canopies, may have nonstandard trim measurements that require more detailed measurements. The rigger should consult the manufacturer’s manuals or technical data for these canopies. 

## Disassembly 

1. The first thing the rigger must do is to complete a measurement of the lines of the canopy. The chart in Figure A shows a matrix for measuring the lines of the canopy. Simply fill in the boxes for each dimension measured. 

2. Start by laying the canopy on the left side, anchor the connector links, and flake it out as if for packing. Most canopy lines are measured from the inside of the connector links, which is called the zero point. 

3. Anchor the end of the tape measure even with the zero mark at the end of the lines using the pony clamp. [Figure B] 

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4. Start with the top outside right front corner line of the canopy. This line will be line 1A. Depending on the number of cells to the canopy, on a 7-cell canopy, the left corner line will be line 8A. On a 9-cell canopy, this line will be line 10A. Make sure that the canopy is oriented correctly so that the measurement sequence follows the boxes on the chart. 

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