Determining the Method of Predictive Maintenance for Aircraft Engine Using Machine Learning

Predictive maintenance (PdM) is indicated state of the machine to perform a schedule of maintenance based on historical data, integrity factors, statistical inference methods, and engineering approaches that are currently often applied to aircraft maintenance. The Predictive maintenance on aircraft to avoid the worse event (failure) and get information about the status of aircraft machines by applied on Machine Learning (ML) to get high accuracy and precision. The research aims to look for the method and technique of ML, which is the best applied on PdM for aircraft in accuracy indicators. The techniques of ML have been divided by classification and regression, which are compared on three ML methods: Random Forest (RF), Support Vector Machine (SVM), and simple LSTM. The result of the study for classification technique are LSTM 98,7%, SVM 95,6%, and RF 900,3%. On other hand, Regression technique for ML result on MAE and RMSE are LSTM 13,55 and 22,13, SVM 15,77 and 20,51, RF 15,06 and 19,98. Classify technique is better and faster than regression when calculating the PdM on an aircraft engine. The LSTM method of ML is the best applied to it because of the accuracy higher and time process faster than other methods in this study. Finally, the LSTM method is highly recommended while using with classify technique on ML to determine the PdM on an aircraft engine.

ECONOMIC AND ECOLOGICAL ASPECTS OF THE USE OF NEW CRYOGENIC AVIATION FUELS

Until recently, the high rates of aircraft engine engineering’s development were ensured by the technological solutions improvement and the desire to approximate as much as possible the ideal thermodynamic cycle of turbojet engines. The traditional fuel for turbojet engines is an aviation kerosene – Jet-A fuel group and their regional analogies. The traditional way of aircraft engines efficiency increasing is a raising of a temperature in front of the high-pressure turbine. New alloys and technologies allow to increase the aircraft engines efficiency to a certain level. Raising the temperature in the combustion chamber by 50 degrees increases the efficiency, which leads to a 5% reduction in fuel consumption. However, this approach is technology limited and does not provide innovative solutions. The aircraft engine engineering’s development tempo in the 21st century continues to accelerate. The main driver of such processes in recent years is the tightening of economic and environmental requirements. Many aircraft manufacturers are actively looking for ways to reach a new qualitative level in terms of turbojet engines economic efficiency and meeting strict environmental requirements. The paper considers the feasibility of using new cryogenic fuels in aircraft turbojet engines, and possible ways for aircraft industry successful development.

Aircraft-engine particulate matter emissions from conventional and sustainable aviation fuel combustion: comparison of measurement techniques for mass, number, and size

Sustainable aviation fuels (SAFs) have different compositions compared to conventional petroleum jet fuels, particularly in terms of fuel sulphur and hydrocarbon content. These differences may change the amount and physicochemical properties of volatile and non-volatile particulate matter (nvPM) emitted by aircraft engines. In this study, we evaluate whether comparable nvPM measurement techniques respond similarly to nvPM produced by three blends of SAFs compared to three conventional fuels. Multiple SAF blends and conventional (Jet A-1) jet fuels were combusted in a V2527-A5 engine, while an additional conventional fuel (JP-8) was combusted in a CFM56-2C1 engine. We evaluated nvPM mass concentration measured by three real-time sampling techniques: photoacoustic spectroscopy, laser-induced incandescence, and the extinction-minus-scattering technique. Various commercial instruments were tested including three LII 300s, one PAX, one MSS+, and two CAPS PMSSA. Mass-based emission indices (EIm) reported by these techniques were similar, falling within 30 % of their geometric mean for EIm above 100 mg/kgfuel (approximately 10 μg PM m−3 at the instrument), this geometric mean was therefore used as a reference value. Additionally, two integrative measurement techniques were evaluated: filter photometry and particle size distribution (PSD) integration. The commercial instruments used were one TAP, one PSAP, and two SMPSs. These techniques are used in specific applications, such as on-board research aircraft to determine PM emissions at cruise. EIm reported by the alternative techniques fell within approximately 50 % of the mean aerosol-phase EIm. In addition, we measured PM-number-based emissions indices using PSDs and condensation particle counters. The commercial instruments used included TSI SMPSs, a Cambustion DMS500, and an AVL APC, and the data also fell within approximately 50 % of their geometric mean. The number-based emission indices were highly sensitive to the accuracy of the sampling-line penetration functions applied as corrections. In contrast, the EIm data were less sensitive to those corrections since a smaller volume fraction fell within the size range where corrections were substantial. A separate, dedicated experiment also showed that the operating laser fluence used in the LII 300 laser-induced incandescence instrument for aircraft engine nvPM measurement is adequate for a range of SAF blends investigated in this study. Overall, we conclude that all tested instruments are suitable for the measurement of nvPM emissions from the combustion of SAF blends in aircraft engines.

Flutter of Fan Blades in the Aircraft Engine in the Three-Dimensional Subsonic Gas Flow

Aeroelasticity problems arise in the different fields of technology. The accident-free operation of the airborne machines is one of the most important factors that should be taken into account during their designing and upgrading. The solution of this problem involves the implementation of many measures to provide the system reliability on the whole, including its individual elements, in particular aircraft engine, its fan whose wide-chord blades can be exposed to the wreckage due to different reasons including the aeroelastic effects, i.e. self-excited vibrations. As a result, the origination of the aeroelastic phenomenon (flutter) in design and off-design modes should be eliminated at the stage of the design and operational development of the rotor wheel that would result in a considerable increase of the level of reliability of the aircraft engine. Based on the analysis of the available methods used for the flutter prediction we can draw a conclusion that the most promising approach to the analysis of the aeroelastic behavior of the blade ring of fan is the use of the method based on the three-dimensional model of the aerodynamics and dynamics (the method used for the solution of the coupled aeroelastic problem). By solving the coupled aeroelastic problem of the nonstationary aerodynamics and elastic vibrations of the blades we can get the amplitude –frequency blade vibration spectrum for the three-dimensional gas flow, including forced vibrations and self-excided vibrations in order to increase the reliability of the blade row of turbine machines. The developed numerical method was used for the analysis of the aeroelastic behavior of the blade ring of the fan mounted in the airborne engine for the operation mode of 3520 rmp with appropriate boundary conditions at the inlet and outlet behind the ring. The computation data confirmed the origination of self-vibrations for the given fan operation mode.

Evaluation of Influence Factors on the Visual Inspection Performance of Aircraft Engine Blades

Background—There are various influence factors that affect visual inspection of aircraft engine blades including type of inspection, defect type, severity level, blade perspective and background colour. The effect of those factors on the inspection performance was assessed. Method—The inspection accuracy of fifty industry practitioners was measured for 137 blade images, leading to N = 6850 observations. The data were statistically analysed to identify the significant factors. Subsequent evaluation of the eye tracking data provided additional insights into the inspection process. Results—Inspection accuracies in borescope inspections were significantly lower compared to piece-part inspection at 63.8% and 82.6%, respectively. Airfoil dents (19.0%), cracks (11.0%), and blockage (8.0%) were the most difficult defects to detect, while nicks (100.0%), tears (95.5%), and tip curls (89.0%) had the highest detection rates. The classification accuracy was lowest for airfoil dents (5.3%), burns (38.4%), and tears (44.9%), while coating loss (98.1%), nicks (90.0%), and blockage (87.5%) were most accurately classified. Defects of severity level S1 (72.0%) were more difficult to detect than increased severity levels S2 (92.8%) and S3 (99.0%). Moreover, visual perspectives perpendicular to the airfoil led to better inspection rates (up to 87.5%) than edge perspectives (51.0% to 66.5%). Background colour was not a significant factor. The eye tracking results of novices showed an unstructured search path, characterised by numerous fixations, leading to longer inspection times. Experts in contrast applied a systematic search strategy with focus on the edges, and showed a better defect discrimination ability. This observation was consistent across all stimuli, thus independent of the influence factors. Conclusions—Eye tracking identified the challenges of the inspection process and errors made. A revised inspection framework was proposed based on insights gained, and support the idea of an underlying mental model.

Being in Control of Noise Levels Improves the Perception of Airplane Seat Comfort

The aviation industry is constantly making compromises when designing comfortable airplane cabins. Providing passengers with a pleasant acoustic environment without adding weight to the cabin structure is a field of tension that challenges cabin interior designers. The aim of this study was to investigate whether noise levels affect the comfort and physical discomfort experienced by airplane passengers, and whether control influences comfort perception. To this end, 30 participants experienced three conditions (silence, aircraft engine noise at 75 dB, and the same noise with the ability to use earplugs), and comfort and discomfort were measured using a questionnaire. It was concluded that aircraft engine noise negatively affected the airplane passengers’ comfort experiences. Having the ability to control this noisy environment with earplugs resulted in the lowest reported physical discomfort.