Investigations of Some Properties of Material Samples Taken from the Aircraft Withdrawn from Service

Materials used in aircraft structures have (should have) certificates confirming their quality. Nowadays, in majority of cases, the symbols of materials used in construction of aircraft give detailed information about their mechanical properties. This general material data is gathered in the widely available engineering material data bases. In the case of materials used in Polish aviation several decades ago, there is no reliable material data crucial for crack propagation estimation or fatigue life estimation among others. Examinations conducted in many different research institutes are not systematized and are not gathered in a remotely accessible data base.

As aging aircraft are concerned, the influence of service time (often exceeding thirty years) on the overall material properties is a very important factor. It may be too crude estimation to use standard material properties when it comes to aging aircraft fleet. Some experimental works concerning this topic are published from time to time and they are always very welcome.

In the Air Force Institute of Technology experimental tests were carried out to determine some specific properties of the materials used in the PZL-130 Orlik aircraft structure. The samples were obtained from aircraft withdrawn from service. This enabled estimating the difference in material properties over time. The following tests were conducted during the experiments:

- fatigue tests (crack propagation examination)

- static tests.

The analyzed material was taken from the central upper part of the aircraft wing. The experiment was conducted with the MTS machine with the 810.23 system.