To reduce the weight of aircraft seats, a major seat manufacturer switched several of its seating elements from aluminum to carbon-fiber-reinforced composites.
This let designers drop the weight of lumbar and thigh supports, armrest-table covers, and shields for in-flight video screens by 40 to 50%.
The Tepex composite produced by Bond-Laminates GmbH (bond-laminates.com) in Germany are laminates of up to 20 layers and feature a matrix made from Fortron polyphenylene sulfide (PPS). DTC (www.composites.nl) in the Netherlands thermoforms the 0.2 to 5-mm-thick sheets into seating components.
Fortron PPS, from Ticona, the engineering polymers business of the Celanese Corp., Florence, Ky., (ticona.com), was the choice for the composite matrix because of its inherent flame retardance. It also has a low smoke index and high limited oxygen index.
"The FST (fire, smoke, toxicity) properties of Fortron PPS combined with the high-strength fibers used in the Tepex composite provide a superior material for aircraft interiors and other applications with stringent safety requirements," says Joost van Lindert, Bond-Laminates managing director. "This material will be a strong contender for many parts."
Fortron PPS composites are known for hardness, rigidity, and resisting impacts and most chemicals, as well as oxidation. They also remain dimensionally stable when exposed to the thermal variations exceeding 100°C often encountered during flight.
PPS composite-lumbar supports at the base of the rear portion of the seat measure 16 30 cm (6.3 11.7 in.) and weigh just 150 gm (5.3 oz). This contrasts with their 280-gm (9.9-oz) aluminum counterpart. The 130-gm (5-oz) weight saved per seat quickly adds up, in that Airbus A380s have a standard seating configuration of 555 seats. Weight difference per A380 aircraft could total 72 kg (158 lb).
"Additionally, PPS composites are easier and less costly to process than aluminum, which undergoes more production steps than formed composites," says Dirk Raudies, Ticona technical marketing manager. "We estimate that parts made with Tepex generate an overall cost savings of up to 25%, compared to aluminum."
"Using Fortron PPS composites is in line with the growing application of all composites in aircraft, which has risen from 7 to 20% since the 1980s," says Raudies. "More than 1,000 Fortron PPS structural and other components currently serve in aircraft, including keel beam rips and the leading edge of the wing."