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Technology update
Crashworthy seat comfort
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Martin-Baker's new helicopter crashworthy seat.
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Ejection seat specialist Martin-Baker launched its new helicopter crashworthy crew seat at the UK's Helitech 99 exhibition. It features adjustable lumbar and thigh support plus adjustable armrests. Crew comfort is a major contributor to reduced fatigue levels and, potentially, enhanced safety. The new crashworthy seat echoes automotive standards of adjustment, with a headrest that can be raised or lowered. Lumbar and thigh support adjustment is via a pneumatic system. The seat is based on Martin-Baker's established lightweight crashworthy crew seat, which meets latest FAR/JAR Pt. 27/29 safety standards, has been tested to Mil-Std 810 environmental test requirements, and has a five-point harness to SAE AS8043 standard.
The crashworthy crew seat consists of a padded, lightweight sheet metal sitting platform mounted on two light-alloy vertical rails and support structure. The new seat is adjustable vertically and longitudinally. Martin-Baker's energy attenuation system involves the use of hardened cutters, one in each of the vertical rails. They pass through the rails and engage in the light-alloy channel on the inside face of each rail. Two shear pins with a minimum pre-determined shear value secure the seat bucket assembly for normal flight. The company explained that if the seat and occupant are subjected to a vertical acceleration in excess of the predetermined load, the pins shear, allowing the bucket and occupant to move downwards on the vertical rails, the cutters shaving off material to limit deceleration to within specified limits.
Martin-Baker crashworthy seats are fitted to a wide variety of helicopters and have been selected, among others, for the NH-90, Sikorsky S-92 Helibus and S-76 C+, Eurocopter EC 135 and PAH-2 Tiger, Denel Rooivalk, and Agusta A129. The crashworthy seat range includes a rotating and traversing type, an armored crew seat for protection against 12.7-mm armor-piercing M2 projectiles, a passenger seat, and utility seat.
Stuart Birch
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