Salacinski, M., Broda, P., and Samoraj, P., "The Repair Design and Technology of Metal Rotor Blades for Mi Family Helicopter - The Approach with the Usage of Reverse Engineering," SAE Technical Paper 2017-01-2155, 2017.
Polish Armed Forces are currently operating hundred helicopters belonging to Mi family. Metal fuselage is usually resistant to the battle and the human factor. Unfortunately, metal rotor blades of Mi helicopters are sensitive to operating conditions. Single blade is made from monolithic aluminum spar and mutually separated trailing sections, which are bonded to the spar. The sections are constructed of metal sandwich panels.During aggressive military operating conditions blades sections are often damaged by debonding from the spar, fatigue cracks of section skin, dents and perforations as well as erosion. The manufacturer assumed that structurally damaged sections should be exchanged. Provided repair technologies are applied only to cosmetic damages. Unfortunately, there is a limit to number repairs which prevents replacement of two neighboring sections due to the high temperature of curing cycle during the section replacement. Additionally the old technology is expensive and time-consuming.Therefore, it was necessary to develop new technologies to enable the repair of rotor blade structural damages.The article presents an approach of designing repair of rotor blades structural damages based on a reverse engineering and selected technological aspects. Description of the substantiation of repair, calculations, environmental, thermo-mechanical and fatigue research have been undertaken.