Preliminary FAA-Hybrid III Spinal Injury Criteria for Oblique-Facing Aircraft Seats

Occupant injury potential to oblique loading at aircraft crash severities is unknown. The objective of the present study was to derive preliminary injury criteria for the Federal Aviation Administration (FAA) Hybrid III anthropomorphic test device (ATD) under oblique loading conditions. Twelve sled tests were conducted at four pulse severities and three configurations. An acceleration pulse representative of the one specified in Title 14 Code of Federal Regulations Part 25.562, emergency landing dynamic condition for horizontal impact was used as an input. Pulses were scaled in magnitude at 50, 61, 75 and 100% of the peak acceleration 13.7, 10.2, 8.6 and 6.8 m/s, respectively. The three conditions were: 45-degrees, no arm rest, pelvis restrained with two belts, legs restrained; 45-degrees, with arm rest, single lap belt, legs restrained; 30-degrees, no arm rest, two lap belts, legs unrestrained. The ATD was placed on a generic seat representative of aircraft seat geometry and the seat was oriented obliquely. ATD accelerations, thoracic and lumbar spine forces, and restraint forces were recorded. Peak tension forces in the thoracic and lumbar spine ranged from 10–12.7 kN at the highest pulse to 3.6–4.2 kN at the lowest pulse. Previously reported in-house post mortem human surrogate (PMHS) tests provided a matched-paired dataset for combining injuries with ATD metrics. From this limited sample set, 5.2 kN tension force in the spine is suggested for the FAA-Hybrid III ATD as a preliminary injury criteria in oblique loading in the aviation environment.