In the article, an ARIMA-Fuzzy-based hybrid model is proposed for forecasting time series of non-scheduled passenger air transportation. As it is known, the ARIMA model is applied to identify linear trends and regularities within time series data as well as for forecasting. The study of scientific research literature shows that the ARIMA model has its own limitations in managing non-linearity and random changes during forecasting. Since the process of non-scheduled air transportation depends on random changes as a stochastic process, the mentioned model does not cover the whole process. For this reason, the ARIMA model does not provide effective enough results outcome strong enough to model non-linear and random changes in the data in the process of non-scheduled air transportation. In this regard, the ARIMA model was applied together with the fuzzy model. The hybrid model, based on ARIMA’s autoregression model, is applied together with the random deviation fuzzy model to further increase the accuracy of the forecast. The results obtained as a result of the application of the hybrid model show that the model in this form provides more reliable and efficient forecasts compared to independent models.

Contamination of the compressor flow path is one of the most prevalent issues encountered during the operation of aircraft gas turbine engines (GTEs). During operation in winter, ingestion of anti-icing fluids and de-icing agents into the compressor flow path presents a substantial risk. In particular, contamination of the compressor rotor blades leads to the reduction in the cross-sectional areas of the inter-blade channels, changes in their shape, and an increase in the roughness of the blade surfaces. All these phenomena compromise compressor performance: result in reduced efficiency, decreased pressure ratio, and airflow, resulting in lower engine thrust, increased jet pipe temperature, higher fuel consumption, reduced gas-dynamic stability, and altered rotor speeds. To eliminate contamination in the gas-air duct during operation, periodic washings of the flow part are performed using solid cleaners, liquid detergents, and water as cleaning agents. The article analyzes changes in deviations of bypass turbo-jet engine recorded parameters from baseline values both when contaminated with anti-icing fluids and after removing contaminants using statistical models based on time series analysis methods, dynamics of model characteristics describing relationships between parameters, as well as synchronization analysis of parameter changes in engines of the same aircraft. The article does not aim to report average parameter change values for a specific engine type and fault but rather demonstrates the principle and effectiveness of the diagnostic method that uses the principle of assessing the dynamics of significance and stability of correlation links between recorded parameters, which are currently underutilized in the scientific-methodological foundations of constructing and applying statistical diagnostic models in operational practice.

The article deals with a method for aircraft maintenance planning based on advanced mathematical modeling techniques. In the course of the research, a mathematical model for forecasting the failure rate of onboard equipment is developed and tested, designed to solve the problems of optimizing decision-making processes for maintenance on the basis of reliability assessment of aviation equipment. The application of Poisson distribution regression in combination with polynomial features allows to reveal the regularities of equipment failures, which depend on operating conditions and maintenance history. For the study, a synthesized dataset was created to simulate different operational scenarios and equipment degradation process. At the first stage, the data were freed from outliers and errors, then normalized to unify the scale of different variables. Next, the data were categorized according to the operating conditions, after which Poisson distribution regression was applied to predict failures. Finally, an efficient maintenance plan that takes into account the predicted failures has been developed using an optimization algorithm. Validation of the model’s predictive capabilities and optimization of the maintenance strategy are performed by comparing with archived data on previously performed work. The analysis of the results revealed the peculiarities of the model operation, namely, the application of least squares regression with single coding demonstrates perfect forecasts, which may indicate the need for model transformation and requires additional verification. At the same time, alternative versions of the methodology revealed more realistic error and correlation limits, which also confirms the reliability of the predictive models. The results of the study show that a combined approach using Poisson distribution regression and polynomial signs can significantly improve the accuracy of forecasts. This method, in particular, has demonstrated its effectiveness in modeling onboard equipment failures, which allows to optimize maintenance processes in order to reduce repair costs. The obtained conclusions confirm the possibility of introducing more accurate proactive methods of maintenance planning, which allows to improve aircraft reliability and reduce the inefficiency of their downtime on the ground.

The article analyses the state of the transport system of the Kyrgyz Republic as an example of landlocked country with a developing economy located in a mountainous area with a large altitude range. The aim of the study is to identify the potential of air transport (AT) in countries with mountainous terrain to ensure connectivity in domestic and international traffic. The study is based on the method of analyzing the topology of the transport network, which allows identifying defects that hinder the provision of a sufficient level of spatial connectivity of the territory. The demand for passenger traffic was assessed by means of statistical analysis of passenger traffic by type of transport for the period from 1991 to 2023 and calculation of indicator of the number of flights per local resident per year. In order to identify the potential demand for passenger carrying operations, a survey of local residents was conducted. The results of the study showed that more than 80 percent of intercity passenger traffic in the republic is carried out by road transport, while 12 percent of settlements are not connected by buses. In many high-mountainous settlements, road traffic is interrupted during certain months due to icing, avalanches and landslides, resulting in transport isolation. Since 1985, there has been a change in the recurrence period of landslides and a shift in seasonal timing from March-May to January-June. It was found that air transport is a popular alternative for passenger traffic during these months. Over the period from 2013 to 2023, passenger traffic at the international airports of Manas and Osh increased more than doubled, and at the reconstructed airports of Issyk-Kul and Jalal-Abad – 27 and 7 times respectively. Insufficient domestic route network, low flight regularity, lack of direct flights to Europe and the USA were identified as the main factors constraining the growth of aviation mobility of the population. The opening of new international flights will make it possible to reach the tourism potential of the republic.

The materials of the article contain the results of an assessment of the stress-strain state, internal equivalent forces and moments of an elastic shell of rotation of a parabolic shape under its dynamic loading by a moving excess pressure front propagating along the axis of symmetry. The nasal part of the shell is reinforced from the inside by a rigid parabolic insert. The presence of a massive object (nose insert) in a dynamic system introduces additional disturbances into the process of unsteady propagation of disturbances in a thin-walled shell. The parameters of the interaction of the shock wave with the surface of the structure are highly localized, as typical time of the process does not exceed 20 milliseconds. The magnitude of the acting moving load on the shell is determined by the function of the total pressure, adjusted using the Heaviside function. The calculation results are given for the option of sealing (rigid fastening) the end of the shell on a fixed mating part. The values of the internal force factors for shells with three versions – 3, 5 and 7 mm thick – are presented in a dimensionless form. The illustrations show the dependences on the time elapsed since the beginning of interaction with the shock wave of the bow for internal forces and bending moments. The nature of the propagation of elastic perturbations in the wall is determined by their superposition and re-reflection, the nature and amplitude of the waves of which depend on the configuration of the wall itself, the conditions of fixation and the parameters of the action of external overpressure. The results of calculating the distribution of force factors along the length of a thin-walled shell at the time when they reach their maximum values in absolute terms are also given. The nature of the overall design change can be obtained by analyzing the final graph, which shows the time changes in the values of the movements of the rigid nose in the longitudinal direction.

The article presents an improved method for assessing the durability of spherical plain bearings, operating under the conditions of oscillatory motion, based on the processing of an array of experimental data obtained in laboratory conditions as well as during operation of the product. One of the options of mathematical modeling was applied, which uses regression methods to approximate the function of one variable. As an object of research, spherical plain bearings installed in aircraft (engine) control systems and operating in cyclic rocking motion are considered. Spherical bearings are plain bearings, and the amplitude of their rocking movements can vary over a wide range from ±20° to ±60°. The problems of calculating the service life of plain bearings are well studied and documented in the relevant standards GOST 1144-75 “Rolling bearings. Methods for calculating durability”, GOST 15084-78 “Plain bearings. Methods for calculating durability”. Spherical bearings are plain bearings, but at the same time, there are many technical applications in which bearings operate under conditions of oscillatory motion, for example, in flap drive units, in aircraft control systems, etc. Features of operating conditions determine the specific types of defects identified in experimental studies. It is shown that the known methods for calculating the durability of plain bearings do not allow obtaining acceptable practical results in assessing the service life of bearings operating in cyclic rocking motion.