Evaluation of a Proposed Modified F/FB-111 Crew Seat and Restraint System

An extensive impact test program was conducted to evaluate a proposed F/FB-111 crew seat and restraint system redesign. A primary objective of the program was to determine whether the overall protection performance of the system might be degraded by the design changes which are intended to alleviate the current high spinal injury rate (34 percent). A total of 187 human impact tests were performed in the cardinal axes, including vertical (up to 10G, 8.1 m/ sec), sideward (up to 8G, 9.2 m/sec), and forward facing (up to 10G, 9.8 m/sec). Subjects were exposed to similar impacts using different seat position adjustments to allow parametric analysis. Measured data included seat acceleration and velocity, head and chest translational acceleration components, triaxial forces acting on the seat pan and footrest, forces acting at the restraint harness attachments, and displacements of various body segments. In vertical impact tests, the forward position of the headrest appeared to cause increased forward acceleration of the head. Vertical impact tests demonstrated increased head accelerations with higher shoulder harness angles. Analysis of restraint loads in sideward impacts showed that more of the lateral support is provided by the lap belt with higher shoulder harness angles. This indicates potentially degraded lateral support of the upper torso with the proposed modification.