Full-scale fatigue test of twin-turboprop transport

When the design work was commenced on the YS-11 transport airplane in 1959, the fatigue behavior of the structure was one of the most cardinal problems in the structural design, then the various design principles were introduced in order to overcome the fatigue problems, and the fatigue test of the full-scale airplane structure was planned to guarantee a fatigue life of 30,000 flight hours. In order to perform the fatigue test of the full-scale air-plane structure, the equipment for the wing fatigue test and for the fuselage fatigue test was developed separately. The former consisted of sixteen hydraulic actuators, controlled automatically, and a program device, being able to program the four different repeated loads; the latter was a familiar water tank in which the fuselage was pressurized by water and loaded, the external loads corresponding to gust loads, standing on the ground loads and the others by actuators. Concerning these tests, the following problems will be explained in our report:

1. 1.
   The structure and operation of the equipment of the full-scale fatigue test.