PSI - Issue 82

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2026) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2026) 000–000 Available online at www.sciencedirect.com

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 82 (2026) 281–287

© 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers Abstract Non-destructive testing (NDT), as part of the aircraft maintenance program, is crucial in ensuring the structural integrity, safety, reliability, and durability of aircraft. The eddy current (EC) method is essential for NDT of aircraft structures (AS) due to its high sensitivity to fatigue and corrosion defects. Developed low-frequency EC probes of the double-differential type can be characterized by their enhanced ability to detect subsurface defects in internal layers of multilayer AS. These types of EC probes were applied to solve various aircraft maintenance problems, including the detection of subsurface defects in multilayer AS, the detection of cracks through repair patches, and the detection of corrosion damage (CD) on the reverse side of AS skin, among others. The last NDT demand was related to detecting the corner-type fatigue cracks originating from ferrous steel rivets in the wing spar through a 5 mm thick skin. The desired result was achieved by applying a developed low-frequency EC probe of the double-differential type in conjunction with the EC flaw detector Olympus 600. The possibility of discriminating the signals obtained for cracks of different lengths and a defect-free rivet was shown. Proposed EC techniques create possibilities for well timed detection of dangerous fatigue damage without disassembling the AS or removing protective coating as part of the AS predictive maintenance program. © 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers Keywords: aircraft maintenance; multilayer aircraft structure; fatigue crack; corrosion pitting; non-destructive testing; eddy current method; rivet. Abstract Non-destructive testing (NDT), as part of the aircraft maintenance program, is crucial in ensuring the structural integrity, safety, reliability, and durability of aircraft. The eddy current (EC) method is essential for NDT of aircraft structures (AS) due to its high sensitivity to fatigue and corrosion defects. Developed low-frequency EC probes of the double-differential type can be characterized by their enhanced ability to detect subsurface defects in internal layers of multilayer AS. These types of EC probes were applied to solve various aircraft maintenance problems, including the detection of subsurface defects in multilayer AS, the detection of cracks through repair patches, and the detection of corrosion damage (CD) on the reverse side of AS skin, among others. The last NDT demand was related to detecting the corner-type fatigue cracks originating from ferrous steel rivets in the wing spar through a 5 mm thick skin. The desired result was achieved by applying a developed low-frequency EC probe of the double-differential type in conjunction with the EC flaw detector Olympus 600. The possibility of discriminating the signals obtained for cracks of different lengths and a defect-free rivet was shown. Proposed EC techniques create possibilities for well timed detection of dangerous fatigue damage without disassembling the AS or removing protective coating as part of the AS predictive maintenance program. © 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers Keywords: aircraft maintenance; multilayer aircraft structure; fatigue crack; corrosion pitting; non-destructive testing; eddy current method; rivet. 8th International Conference on Structural Integrity and Durability (ICSID2025) Detection of hidden fatigue cracks in multilayer aircraft structures by double-differential type eddy current probes Valentyn Uchanin a,b,* , Giuseppe Nardoni b , Marco Feroldi b , Mario Turconi c a Karpenko Physico-Mechanical Institute of National Academy of Sciences of Ukraine, Naukova Str. 5, Lviv 79060, Ukraine b I&T Nardoni Institute, Via della Cascina Pontevica 1B, Folzano–Brescia (BS) 25010, Italy c Leonardo – Aircraft Division, Corso Francia 426, Torino (TO) 10143, Italy 8th International Conference on Structural Integrity and Durability (ICSID2025) Detection of hidden fatigue cracks in multilayer aircraft structures by double-differential type eddy current probes Valentyn Uchanin a,b,* , Giuseppe Nardoni b , Marco Feroldi b , Mario Turconi c a Karpenko Physico-Mechanical Institute of National Academy of Sciences of Ukraine, Naukova Str. 5, Lviv 79060, Ukraine b I&T Nardoni Institute, Via della Cascina Pontevica 1B, Folzano–Brescia (BS) 25010, Italy c Leonardo – Aircraft Division, Corso Francia 426, Torino (TO) 10143, Italy

* Corresponding author. Tel.: +38-067-229-6166; fax: +38-032-264-9427. E-mail address: vuchanin@gmail.com * Corresponding author. Tel.: +38-067-229-6166; fax: +38-032-264-9427. E-mail address: vuchanin@gmail.com

2452-3216 © 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers 2452-3216 © 2026 The Authors. Copy from the contract: Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers

2452-3216 © 2026 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID organizers 10.1016/j.prostr.2026.04.043