Analysis of spectrometric data of aeroengines to establish hazard threshold limits for Iron content

As aero-engines operate, metal and other material particles are removed from the contact surfaces and are carried away in the flow of lubricating oil. Spectrometric Oil Analysis Program (SOAP) is a powerful tool for elemental analysis of structural metals in the lubricating oils circulating inside the machine, and is suitable for determining wear metal quantity, elemental composition, rate of wear and its source. The oil samples from the aero-engines are analyzed through spectrometry and the readings are assessed against pre-defined values to ascertain the physical health of the engines. This method is employed to continuously monitor the condition of the engine internal parts without any stripping, thus reducing maintenance time and costs. The predefined values or limits for SOAP are defined by the Original Equipment Manufacturer and are normally formalized during design process of the equipment. For the Chinese range engines powering the fighter jet aircraft, the limits for SOAP are not defined and thus this valuable technique cannot be fully applied to these engines. As a consequence the benefits of continuous condition monitoring together with reduced maintenance cost and time are not fully accrued. Iron (Fe) is the major element of the engine internal parts and its inclusion in oil sample gives a clear picture of the wear and tear of the engine internal parts. In order to accrue benefits of SOAP on Chinese range aero-engines there is a need to define the alert and hazard thresholds limits for SOAP on these engines. Once defined, the SOAP data can be used to decide about the continued operation of the engine or its induction for maintenance. In this paper the SOAP data for Chinese range engines operating in the fighter aircraft is collected and then it is statistically analysed to establish the limits for alerts and hazard for Iron (Fe).