Abstract: An airframe includes an energy absorbing structure with a frame, a beam mounted to the frame at a rotational joint and a collapsible member. In response to reaching a predetermined threshold load value during a high sink rate impact event, the collapsible member will collapse under an aft section of the upper deck. The rotational joint operates as a virtual hinge such that a forward section of the upper deck deforms in a predictable manner. As the upper deck supports the high mass systems, the high mass components are less likely to separate from their mounting and penetrate into the crew compartment and the main rotor system will tilt aft away from the crew compartment to minimize the likelihood that the rotor blades may penetrate the crew compartment.

Abstract: A pressure tolerant composite panel has an inner fiber reinforced layer, an outer fiber reinforced layer and an core disposed therebetween. In one embodiment of the invention, the inner layer has weakening structures incorporated at the peripheral edges thereof, and has an outer layer of a different and lower modulus of elasticity than the inner layer to provide some degree of elongation. When high internal forces are encountered, the weakening structures allow the inner layer to separate, with the outer layers stretching to absorb the forces without failure. Optionally, strengthening straps are position about the panel such that it is compartmentalized into discrete sections to contain damage in localized areas. In an alternative embodiment of the invention, the inner core is produced of a crushable material which has a yield strength sufficient to provide structural support under normal operating conditions.