Effects of Aircraft Size on Cabin Floor Dynamic Pulses 881379

Recent Federal Aviation Administration (FAA) regulatory actions (both a rule and proposed rules) have introduced dynamic test requirements for seats in the form of acceleration versus time triangular pulses. This paper summarizes a recent FAA sponsored effort to update size scaling trends for airplane cabin floor crash pulses.

The dynamic pulses for different category airplanes are summarized and compared. An investigation into the effect that airplane size has on dynamic floor pulses generated within the airplane cabin during a crash impact event is discussed, including:

• A review of narrow-body and wide-body section test results and supporting analytical model results.
• The utilization of the Controlled Impact Demonstration (CID) validated KRASH model to perform additional parametric studies.
• The definition of relationships between parameters which influence aircraft structure dynamic response.
• The development of airplane preliminary size effect trend curves for cabin floor dynamic pulses in terms of triangular pulse, acceleration magnitude, velocity change and pulse duration.

A simple approximate expression relating aircraft fuselage crush energy dissipation and kinetic energy was utilized to generate a set of triangular pulse velocity - crush distance - peak acceleration curves. Estimated effective crush distances for various classes of airplane sizes or categories and measured acceleration, velocity and crush data were plotted. Blots for vertical-direction and longitudinal-direction are presented. A preliminary size trend curve range is established for each of the two directional pulses. The vertical pulse trend curves are based on enveloping all the applicable measured and analytically developed data. The longitudinal trend curves assume that the survivable envelope ranges from the fringes of known survivable conditions to nonsurvivable crash test results.

The size effect study emphasizes that the results are more configuration sensitive and not directly related to mass. Large airplanes with limited effective crush regions could behave more like some smaller airplanes with regards to the character of the cabin floor pulses.