REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

CONTRIBUTION TO THE MAINTENANCE OF Mi-8 HELICOPTER IN THE SERBIAN AIR FORCE

ZORAN ILIĆ

Technical Test Center, Belgrade, zoranilic_65@yahoo.com

BOŠKO RAŠUO

Faculty of Mechanical Engineering, Belgrade, brasuo@mas.bg.ac.rs

MIROSLAV JOVANOVIĆ

Technical Test Center, Belgrade, mjovano@sbb.rs

LJUBIŠA TOMIĆ

Military Technical Institute, Belgrade, ljubisa.tomic@gmail.com

STEVAN JOVIČIĆ

Technical Test Center, Belgrade, stevanjovicic@gmail.com

RADOMIR JANJIĆ

Technical Test Center, Belgrade, lari32@mts.rs

NENKO BRKLJAČ

Technical Test Center, Belgrade, brkljacnenko@gmail.com

Abstract: Modern helicopters are equipped with Health and Usage Monitoring Systems (HUMS). Serbian Air Force helicopters are not equipped with HUMS. One of the most effective ways to control state of helicopter is vibration measurement, i.e. defining frequency spectrum using appropriate equipment. Based on the analysis of vibrations, measured on helicopter, it is possible to determine the various types of failures and improper function of component parts or aggregates. The basic problem is to determine vibration amplitudes that are characteristics of proper work, and which ones are characteristics for incorrect operation of  helicopter. In the case of frequency spectrum disorder due to reduction of function of certain working elements, amplitudes of vibration will be increased on speeds of these elements. In such circumstances, the only way to assess condition of helicopter is a comparative analysis of results previously measured vibrations and present measurements. All measurements are should be done at the same places and equipment with the same characteristics. This paper presents results of the analysis and vibration measurements, which were performed at helicopters Mi-8. It was stated a few examples of observed irregularities of individual parts and clear guidelines for taking action to maintain are given.

Keywords: helicopter vibrations, blade, fault, vibration measurement, maintenance.