APPROACH TO STRUCTURE MONITORING OF THE MI-24 HELICOPTER

Mi-24 helicopters have been introduced to Polish Army in late 1970s. Due to the necessity to extend their service life and planned modernization the Ministry of Defence approved preparation and execution of the complex Service Life Extension Program for these helicopters. Basing on the previous proven track of test delivery, the Air Force Institute of Technology (AFIT) was selected to prepare concept, control and supervise the Full Scale Fatigue Test (FSFT) concept of the Mi-24 helicopter structure as well as introduction of the onboard loads and vibration monitoring system (SMST) in order to extend the service life based on the monitoring the actual health. The FSFT run was delivered by the PZL-Świdnik (a LEONARDO HELICOPTERS company) under the AFIT supervision and control. Consecutively for the safety structure operation the health and condition monitoring system (SMST) was developed. The SMST is a system incorporating strain measurements in selected regions (for operational load monitoring), as well as vibration sensors monitoring the power transmission system and corrosion as well as structure monitoring sensors. The strain and corrosion measuring system was already installed on one Mi-24 helicopter designated for test flights, which provided load data for FSFT load spectrum definition. Structure under FSFT was also instrumented with partial SMST system for the purpose of the crack and failure mode monitoring as early as possible due to the remote AFIT supervision. At present preparation for the design and implementation fully functional SMST system onboard of the Mi-24 helicopter for operational structure monitoring has been provided at AFIT. Article will present effort to FSFT delivery, development of the SMST system, results obtained for in flight tests as well as for FSFT. Article will also provide with description of the SHM technologies developed at AFIT and used for aircraft operation. Finally future work plans will be presented for Mi-24 helicopter.