FAA Office of Aerospace Medicine 
Civil Aerospace Medical Institute 

Report No: DOT/FAA/AM-23/17

Title and Subtitle: Seat and Occupant Response in Energy Absorbing Seats

Report Date: June 2023

Authors:Taylor, Amanda M.; Moorcroft, David M.

Abstract:The Federal Aviation Administration (FAA) has undertaken research programs to support streamlining various facets of the seat certification process. Previous research evaluated potential methods to qualify replacement of worn seat cushions used in low G applications (Part 25 and Part 23 passenger) and better quantify variability in vertical testing. The current research focused on higher energy rotorcraft environment where seating systems have energy absorption built in to reduce an occupant’s risk of spinal injury. To gain a better understanding of how a seat with energy absorption characteristics behaves during a vertical test, the FAA’s Civil Aerospace Medical Institute (CAMI) tested two seats with different styles of energy absorption: motion of the seat relative to the frame and buckling of the bottom of the seat only. Additionally, a simplified rigid seat test was used to evaluate whether the recorded seat pan acceleration of a stroking seat can be applied to the entire sled and provide similar occupant response to the original test. The stroking seat absorbed energy by creating a phase shift between the lumbar load and the sled deceleration. The buckling seat acted as a load limiter. Both methods of energy absorption reduced the measured lumbar load to below the magnitude expected from a fixed, rigid seat. For the rigid seat test, magnitude and phase differences between the original test and the simplified test suggest that this method may not be a suitable replacement for a full-scale test. Combining these results with those from projects focused on Part 23 and Part 25 conditions, a simplified method of cushion replacement for Part 27/29 rotorcraft is not recommended at this time.

Key Words: Energy Absorbing Seats, Lumbar Load, Seat Pan Acceleration

No. of Pages: 30