PSI - Issue 14

Manu Jain et al. / Procedia Structural Integrity 14 (2019) 184–190 Manu Jain / Structural Integrity Procedia 00 (2018) 000–000

185

2

This paper describes the need, requirements, methodology including the Non Destructive Test (NDT) methods and preventive maintenance procedures and lessons learnt from the life extension of Lakshya and Nishant UAVs. These UAVs have been designed for unique roles and operations, they have special requirements for recovery / retrieval which limits their operational life. 2. Life extension necessity 2.1. Design predicted life It is very difficult to provide full life cycle clearance/prediction at initial stages of design because of non availability of data on exact operations, storage conditions etc. Thus it is prudent that initial life be decided conservatively with maximum safety and extreme conditions taken into account and after completion of initial life period UAV can be subjected to inspection and tests. If UAV clears inspection and tests its life can be extended. This also enables a better understanding of how the operating environment effects the performance and life of UAV. 2.2. Usage pattern The usage pattern of the services are quite different. In some cases full flying life is consumed within years and it is not advisable to discard the airframe as it still has a lot of residual calendar life. In other cases full calendar life is completed without even reaching half of operational life. This variation in usage affect the availability of UAV for operations and sometimes leads to increase in buffer stock/inventory. It is prudent to extend the life of aircraft so that it can be utilized to its full potential, without increasing the level of inventory. 2.3. Time and resource constraints It may not be always possible to replace a UAV immediately due to limits of supply line and resources. Life extension of UAVs helps in this and UAVs can be effectively utilized in the time of need. 2.4. Economy of use Life extension also helps in reduction of UAV cost. Total cost can be amortized over more number of operations/flights. This also help in rationalization of fleet strength.

3. Requirements for life extension of UAV 3.1. Study of effect of operational environment on UAV

As the UAV is deployed in the actual operational environment, it is essential to constantly monitor the effect of structural damage, load patterns experienced, corrosion and upgrade the design data for prediction of actual life. This study also provides better understanding and effectiveness of maintenance procedures, which can be suitably modified to cater for environment conditions. 3.2. Identification of critical components Critical components are identified based on the wear/tear and frequency of replacements and can be subjected to detailed inspection and preventive maintenance. This also helps in inventory management. This data helps in focusing the life extension procedure to the essential components.