Abstract : Any cargo that is freely suspended from a helicopter fuselage, by any of several available methods, does not experience the same dynamic loads as the aircraft. For various reasons the load factors may be amplified and peak out of phase with those of the helicopter. This has long been suspected as a major contribution to premature failures in slings, pendants, and attachment points at the aircraft or cargo. A theoretical analysis of the load factor relationship during various flight maneuvers was conducted by Sikorsky Aircraft in 1971 by means of a hybrid computer simulation of the coupled motion of a CH-54 helicopter and several types of external loads, conducted in real time and nonreal time on a fixed-base and a moving-base simulator. Actual flight tests have now been performed on a CH-54 helicopter to investigate the validity of that part of the simulator program from which was derived the relationship between helicopter load factor and sling tension load factor.