Abstract
The objective of this research article is to carry out the shelf life extension study of imported main seat ejection cartridges for trainer aircraft application. The deterioration of various chemical compositions and its properties takes place for the propellants inside the ejection cartridges over a time, even at ambient storage conditions. Life extension is a methodology/technique to assess an impact of environment and induced stresses as per selected methods. Internal ballistics parameters like maximum pressure, time to half maximum pressure, and corresponding time to maximum pressure are generated by firing these cartridges in a Vented Vessel (VV). A VV is designed and fabricated for evaluating and recording these parameters. These parameters are measured using Data Acquisition System (DAS). Experiments are performed to assess the remaining useful life in terms of internal ballistic performance parameters and accordingly extended the shelf life of seat ejection cartridges. The statistical analysis of these performance parameters are evaluated after subjecting to Highly Accelerated Life Trials (HALT). The trial results show that performance parameters are more consistent in cold conditions than in hot conditions. Further, the maximum pressure is higher in cold condition than in hot condition. This is attributed to unpredictable behaviour of the propellant in Original Equipment Manufacturer (OEM) cartridge. After statistical analysis, it is observed that the spread in standard deviation in Phase I at hot and cold conditions are smaller than that of Phase II. This research article describes about the shelf life extension methodology of imported main seat ejection cartridges to enhance the shelf life for aircraft application. This kind of study is essential and helps to keep the entire aircraft fleet in operational readiness. Considering the overall performance of imported main seat ejection cartridges in hot and cold conditions, the maximum pressure (Pmax) varies from 9.70 to 10.91 MPa, time to 1/2 Pmax varies from 730.70 to 790.00 ms and time to Pmax varies from 245.58 to 269.25 ms.
