DISTRIBUTION A. Approved for public release; distribution unlimited.
EN-SB-10-002-Appendicies, Page 1 of 19
Number: EN-SB-10-002-Appendix A
Subject: Evolution of Air Force Crash Load and Cargo Restraint Requirements
Introduction:
During the development of the Senior Leader In Transit Command Capsule
(SLICC), a type of passenger transport module, ASC/EN and the Program
Offices held discussions pertaining to current United States Air Force (USAF)
crash load criteria in order to identify the applicable crash load criteria. These
discussions lead to the compilation of historical crash load criteria, cargo restraint
criteria and lessons learned. The purpose of Appendix A to EN-SB-10-002 is to
document the historical development and progression of crash load and cargo
restraint criteria.
Background:
When a crash occurs, the primary requirement is to assure the occupants (crew
& passengers) are able to survive and egress. This is accomplished by making
sure that cargo and equipment does not break off and become a projectile during
crash deceleration (thus causing injury) and by assuring egress requirements are
met.
Originally called “Emergency Landing Loads,” crash loads are a consideration in
airframe design. Application of crash load criteria will result in an airframe that
provides a balance between passenger safety, weight of the structure, and the
cost of the system. The primary parameters which affect occupant survival in a
crash environment and are considered in the design of a crashworthy airframe
are terrain, aircraft descent angle, aircraft impact attitude, and aircraft velocity. A
crashworthy airframe acts to retard the total destruction and complete rupture of
occupied areas and reduce the accelerations experienced by the occupants.
Historical Perspective on Crash Load Criteria
The origins of crash-load restraint criteria are hard to trace back to their
beginnings. The consequences of crash landings first became a concern during
the early days of flying in Dayton, Ohio. Just ten years after the Wright Brothers
delivered the first American military aircraft, World War I aircraft experiences with
fire after an emergency landing became a problem. Early aircraft were made
mostly of hardwood (braced with steel wires) and covered with a linen fabric that
was doped to provide the stiffness required to form a wing surface. Most aircraft
were structurally fragile by today’s standards and were susceptible to fire.
Early testing was focused primarily on fire safety, not load factors. In an effort to
prevent aircraft fires during emergency landings, the Wright Field Engineering
