Vol.9, No2, 2009, pp. 89-112
UDC 629.735.3.018.4

Abstract

Over recent years Australia has been involved in a number of full-scale fatigue testing programmes in support of the through-life structural integrity of the Royal Australian Air Force (RAAF) F/A-18 Hornet fleet. It was recognised early in the acquisition cycle that the certification testing conducted by the manufacturer would be unlikely to cover the typically more severe and diverse RAAF operations. The Canadian Forces (CF) also shared this position. Given similar aircraft structural integrity management philosophies, both parties foresaw that major benefits could be realised through collaboration. In particular, as the basis for both countries’ structural integrity management, fatigue testing under representative loading CF/RAAF was considered as essential, thus the International Follow-On Structural Test Project (IFOSTP) was born. Subsequently, the lack of in-service induced degradation (e.g. corrosion, mechanical damage) in these laboratory tests was identified as a risk for their interpretation. To address these interpretation issues and to reduce the risk of blindly accepting the results of limited testing, fatigue life expired ex-service centre fuselage bulkheads were fatigue cycled and torn down to inspect for in-service degradation. After that, additional sub-component tests were carried out as part of a programme to reduce the numbers of repairs the aircraft required during service to meet its planned withdrawal date and to address regions of the aircraft that no longer meet the original design requirements due to in-service modifications. Some of these tests are described.

This paper emphasises the Australian components of IFOSTP, the enhanced teardown of ex-service structure and several sub-component tests born from the teardown testing. Several of the innovations and consequences of this work programme are highlighted. These may be applicable to future aircraft structural integrity programmes.

Keywords: F/A-18 aircraft, fatigue testing, cracking (fracturing), defects (materials), buffet loadings