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This technical paper presents the author's recommended approach to one aspect of managing flight safety - conducting Safety Risk Analyses (SRA) on in-service problems that may threaten flight safety. The author did not develop this statistically based approach for assessing the risk of future events, but has helped to improve it and highly endorses it. In conducting a safety risk analysis, the analyst might decide to perform a “quick” SRA and will need a minimal amount of information that will show the relative level of flight safety risk. When the analyst decides a complete safety risk analysis is needed, the possible approaches and level of details included in the SRA can vary greatly from company to company.

Engine module performance trending and engine system anomaly detection and identification are core capabilities for any engine Condition Based Maintenance system. The genesis of on-condition monitoring can be traced back nearly 4 decades, and a methodology known as Gas Path Analysis (GPA) has played a pivotal role in its evolution. GPA is a general method that assesses and quantifies changes in the underlying performance of the major modules of the engine (compressors and turbines) which directly affect performance changes of interest such as fuel consumption, power availability, compressor surge margins, and the like. This approach has the added benefit in that it enables anomaly detection and identification of many engine system accessory faults (e.g., variable stator vanes, handling and customer bleeds, sensor biases and drift). Legacy GPA has been confined to off-board analysis of snapshot data averaged over a stable flight conditions when the engine is in steady state operation.

This paper provides an insight into how the introduction and implementation of the blending borescope used to perform on-wing blending of compressor blades on Pratt & Whitney (P&W) Engines has resulted in significant savings. It describes the following: Commercial statistics and savings; Military statistics and potential savings; P&W maintenance team; What is on-wing blending; The capabilities of on-wing blending; The contents of a typical blending borescope inspection kit; Test results; Measurement of Foreign Objects Damage (FOD); Installation of the equipment; How to blend FOD; How to measure the repair and observe how the equipment provides precise results; How to polish the repair. Typical commercial cost savings for blending assembled compressors are in the order of $360,000.00 per event, compared with engine teardown cost.

In the present study, an experimental investigation was conducted to characterize a hot-air-based anti-/de-icing system for the icing protection of aero-engine inlet guide vanes(IGVs). The experimental study was conducted in a unique icing research tunnel available at Iowa State University (i.e., ISU-IRT). A hollowed IGV model embedded with U-shaped hot-air flowing conduit was designed and manufactured for the experimental investigations. During the experiments, while a high-speed imaging system was used to record the dynamic ice accretion or anti-/de-icing process over the surface of the IGV model for the test cases without and with the hot-air supply system being turned on, the corresponding surface temperature distributions on the IGV model were measured quantitatively by using a row of embedded thermocouples.

The global electric and hybrid aircraft market utilizing lithium-ion Energy Storage Systems (ESS) as a means of propulsion, is experiencing a period of extraordinary growth. We are witnessing the development of some of the most cutting-edge technology, and with that, some of the most complex challenges that we as an industry have ever faced. The primary challenge, and the most critical cause of concern, is a phenomenon known as a “Thermal Runaway”, in which the lithium-ion cell enters an uncontrollable, self-heating state, that if not contained, can propagate into a catastrophic fire in the aircraft. A Thermal Runaway (TR) can be caused by internal defects, damage, and/or abuse caused by an exceedance of its operational specifications, and it is a chemical reaction that cannot be stopped once the cell has reached its trigger temperature.