How Things Work: Evacuation Slides
De-plane in the fast lane.
- By Mark Huber
- Air & Space magazine, November 2007
(Page 2 of 2)
The inflated slide must flex precisely under a variety of weights to enable passengers to slide down quickly but not so fast that they are injured when they reach the bottom. In order to ensure that 800 passengers could exit an A380 in 90 seconds, its dual-lane slides are qualified to transport 70 passengers in one minute.
Developing modern slides is “like trying to balance a sheet of plywood on the head of a pin by throwing nickels at it from 50 yards away,” says Mark Robertson, a Goodrich vice president for engineering and quality, describing the amount of old-fashioned trial and error necessary. At its Phoenix plant, Goodrich uses an environmental chamber, six giant wind machines, elevated aircraft test fixtures including actual aircraft doors, and darkened tunnels connected to the doors for test jumps onto slides in simulated rain and nighttime conditions. For a standard dual-lane slide, test subjects make as many as 50 test runs at various pressures and door sill heights.
According to Goodrich, the reason passengers sustain injuries during evacuation is that they ignore instructions and hesitate or stop at the end of the slide, making them collide with other evacuees coming down, or instead of sitting upright, they lie down and descend too fast. Targets on the slide and built-in light-emitting diode (LED) lights give evacuating passengers aim points for jumping on and off.
Because slides must often function as life rafts for as many as 87 people, Goodrich conducts trials off the coast of Santa Barbara, California, where ocean conditions closely approximate those set forth in FAA regulations for exit slide performance.
With proper maintenance, a slide will last 15 years. Every three years a slide is deployed, removed, inspected, re-tested, re-packed, and re-installed. The inspection cycle is a way to make sure that slides will perform as they did last August, when a China Airlines 737 arriving in Okinawa experienced an engine explosion, and all 165 aboard escaped safely on inflatable slides just before the plane burst into flames.