The part played by strength testing in establishing structural integrity and efficiency is well known to aeronautical engineers. In principle, the great advances made in structural theory and stressing methods should lessen the pressure on strength testing facilities. In practice, things do not seem to work out this way. For this there appear to be two reasons. The first is the continuous change in aircraft structural design to meet new or more exacting operational roles. The second is the demand for still lighter structures without prejudice to safety. Strength testing, therefore, is as necessary as ever it was if the best results are to be obtained.

For a great many years structural strength testing meant just static strength testing. This is no longer true, since for many types of aircraft fatigue testing has become at least as important as static testing.