When a slide arrives in the "shop" it follows a multi-step process, captured in the attached time-lapse video. Slides younger than 15 years visit the "shop" for inspection every three years. Slides older than 15 years are tested every year.
First, the slide is "flat-fired," or expanded. Then it is "over-pressured," where AMTs inflate the slide with 4.8 pounds of air pressure—more than double its regular capacity. In order for the slide to pass inspection, it must hold this pressure for anywhere from five to 15 minutes.
After checking the relief valve, the slide is allowed to stabilize, or rest, for an hour. Then the real test begins. Each slide must sit inflated with the regulation two pounds of air pressure for two to four hours (depending on the brand). When assessing whether a slide has passed or failed, AMTs use a formula that considers several variables, including ambient temperature and barometric pressure.
When the slide passes inspection, the folding and packing begins. The deflated, folded slide is packed into the boxes (called valises) that are in aircraft doors. Then, depending on the brand, it is either attached to a high powered vacuum called a "suck box" for an hour or baked in a convection oven at 125 degrees for twelve hours to compact it by removing all the air from the slide. This part of the process reminds me of packing for a long trip when one would use industrial strength Space Bags. Once all the air is removed from the slide, the hour-long process of folding begins. Once folded and inside the valise, a pin is inserted to prevent the slide from expanding. During installation, an AMT must remove the pin and complete the installation process within 30 minutes or the slide will begin to fill with air and expand outside of its valise. If that time period is exceeded, the slide returns to the shop for re-packing.
Many thanks to James S., Jerry W., and the entire slide shop Team in DAL for their expertise. Together, the six AMTs in the DAL Slide Shop have more than 130 years experience in aircraft maintenance.