Fabrics are put through physical, chemical and textile tests. Johan Frithiof reports.
Technology used within the production of aeroplanes has become more sophisticated and innovative as a result of stricter legislation. Regulations have been refined over the years following analysis of transportation accidents, to ensure the safest and most robust aeroplanes.
With the expertise to respond to these developments, particularly in the manufacture of emergency escape slides, is Trelleborg's engineered fabrics operation.
Johan Frithiof, Commercial Director within Trelleborg Coated Systems, commented: "Design requirements of airliner evacuation slides have become increasingly more stringent. In the 1960s they had to be deployed in 25 seconds in non-extreme weather, meaning no wind and only medium range temperatures. Now, the FAA states that slides must deploy in just six seconds, in heat ranging from -65 to 160 degrees Fahrenheit and winds of up to 25 knots (28.7mph)."
There are three main categories of requirements used for evacuation system design and operation - the FAA's Technical Standard Order (TSO) C69 which defines mostly performance criteria, FAR and JAR 25 which cover airworthiness standards and FAR 121 and JAR OPS 1 which define operating requirements.
Specifically, the FAA's TSO-C69 has seen numerous additions over the years, following testing, analysis and safety requirements from the National Transport Safety Board (NTSB), with its original issue on 15th August 1961. Since then, TSO-C69a was issued on the 3rd June 1983 to include radiant heat testing requirements in case of a fire, increased material flammability and revised strength requirements of the slide's material.
The evacuation rate was increased from 30 to 60 evacuees per minute, inflation time decreased from 25 to 10 seconds, the requirement for side guards and self illuminated slides, as well as deployment capabilities in 25 knot winds. At least five deployment and erection tests must be demonstrated without failure to prove performance.
On the 17th August, 1988, TSO-C69b was launched which required for the off-wing slide ramp floor fabric to be puncture proof and inflation times were decreased from 10 to 6 seconds. An additional wing-to-ground slide required the device to automatically erect from 15 to 10 seconds, after actuation of the inflation control.
Finally, on the 18th August, 1999, the latest guidelines were introduced under TSO-C69c, which included the increase of evacuation rate from 60 to 70 passengers per minute, per lane, the addition of a beam strength test to accommodate three evacuees sliding down together and the requirement of testing in the dark with naive subjects to test the lighting system efficiency. In addition, radiant heat testing requirements meant that the pressure holding materials must meet the 90 second minimum-time-to-failure requirement and the 180 second average-time-to-failure.
Frithiof continued: "Trelleborg puts all of its fabrics through physical, chemical and textile tests to ensure that elements such as tear strength, flame-resistance and aging, for example, are all carefully considered and measured to ensure compliant solutions every time.
"The nature of emergency products means that you hope they never have to actually be used. But, when they are needed it is imperative that they are in full working order."
For more information at www.engineerlive.com/ede
Johan Frithiof, Commercial Director within Trelleborg Coated Systems, Trelleborg, Sweden. www.trelleborg.com/en/Engineered-Fabrics