Abstract
Widespread production misdrills in Royal Australian Air Force (RAAF) PC-9/A wing main spar lower caps were a potential threat to airworthiness and fleet availability late in the service life of the aircraft. A rapid, novel, enhanced teardown of a retired RAAF PC-9/A wing spar with production misdrills was successfully completed to address this risk. Dynamic block loading was applied to the main spar lower cap of a wing with multiple misdrill indications identified in-service using x-ray inspection. Using an enhanced teardown experimental method and cycling the wing at resonance, fatigue failure occurred within the test section from a main spar misdrill in less than fifty cumulative hours of cycling. A damage tolerance prediction, testing results, teardown inspection and forensic assessment of the spar lower cap was combined to deliver timely and valuable risk mitigation advice for PC-9/A fleet structural integrity managers. Greater confidence in existing fleet management was fostered in a very short timeframe and the opportunity presented by a retired wing with misdrills was fully leveraged. In addition, an innovative structural experimentation method for aircraft sustainment was pioneered.
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Acknowledgements
The authors would like to acknowledge the RAAF and Capability Acquisition and Sustainment Group (CASG) for providing the retired PC-9/A wing used as the test article in this program. We would also like to acknowledge QinetiQ Australia for their work fabricating reaction structure as well as integrating and assuring electrical compliance of the amplifier and shaker system. The authors would like to acknowledge Mr Carl Mouser for performing each of the GVTs at various stages of the test and the authors also gratefully acknowledge the support and encouragement of Professor Pier Marzocca of RMIT University, Wing Commander Ravinder Singh of DASA and Mr Lorrie Molent of DST Group.
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Main, B., Muller, K., Konak, M., Jones, M., Sudhakar, S., Barter, S. (2020). Evaluation of a PC-9/A Wing Main Spar with Misdrills Using Enhanced Teardown at Resonance. In: Niepokolczycki, A., Komorowski, J. (eds) ICAF 2019 – Structural Integrity in the Age of Additive Manufacturing. ICAF 2019. Lecture Notes in Mechanical Engineering. Springer, Cham. https://doi.org/10.1007/978-3-030-21503-3_70
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