Aircraft Operations Research Articles

Preliminary Performance Analysis of Medium-Range Liquid Hydrogen-Powered Box-Wing Aircraft

This paper proposes a performance analysis of a medium-range airliner powered by liquid hydrogen (LH2) propulsion. The focus is on operating performance in terms of achievable payload and range. A non-conventional box-wing architecture was selected to maximize operating performance. An optimization-based multidisciplinary design framework was developed to retrofit a baseline medium-range box-wing aircraft by designing and integrating the fuel tanks needed to store the LH2; several solutions were investigated for tank arrangement and layout by means of sensitivity analyses. As a main outcome, a performance analysis of the proposed LH2-powered box-wing aircraft is provided, highlighting the impact of the introduction of this energy carrier (and the integration of the related tank systems) on aircraft operating performance; a comparative study with respect to a competitor LH2-retrofitted tube-and-wing aircraft is also provided, to highlight the main possible operating differences between the two architectures. The findings reveal that the retrofitted box-wing can achieve long-range flights at the cost of a substantially reduced payload, mainly due to the volume limitations imposed by the installation of LH2 tanks, or it can preserve payload capacity at the expense of a significant reduction in range, as the trade-off implies a reduction in on-board LH2 mass. Specifically, the studied box-wing configuration can achieve a range of 7100 km transporting 150 passengers, or shorter ranges of 2300 km transporting 230 passengers. The competitor LH2-retrofitted tube-and-wing aircraft, operating in the same category and compatible with the same airport apron constraints, could achieve a distance of 1500 km transporting 110 passengers.

Comprehensive Evaluation of Anti-icing Performance and Operational Efficiency of Superhydrophobic Propellers.

The icing of propellers is a critical factor that affects the safe operation of aircraft. A superhydrophobic surface, with its extremely low wettability, is highly valuable in the field of anti-icing. This study investigates the distribution pattern of ice on propeller surfaces by employing spray coating to create superhydrophobic surfaces. Additionally, it conducts a comparative analysis of thrust and power under icing and non-icing conditions to comprehensively assess the impact of superhydrophobic surfaces on propeller operation efficiency. The results show that superhydrophobic surfaces not only diminish the ice formation area on propeller surfaces but also enhance the traction of propellers under icing conditions, reducing the power consumption of the propeller. The generated thrust can reach up to 1.6 times that of non-superhydrophobic propellers while consuming only one-third of the power. Furthermore, under non-icing conditions, superhydrophobic surfaces exhibit minimal impact on propeller performance.

Experimental studies of the influence of elastic-dissipative parameters of engine mounting units on the dynamic characteristics of the “wing model – elastic pylon – engine” system

A feature of modern heavy transport aircraft is their layout with engines on elastic pylons under the wing, with the fuel tanks located in the wing consoles. In this case, the main elastic tones of the aircraft’s own oscillations, which determine its dynamic response to external disturbing influences, include the so-called motor tones (vertical and horizontal (lateral) oscillations of engines on elastic pylons). A new type of flutter has appeared – pylon, which for some aircraft determines the critical flutter speed of the aircraft as a whole. The main reason for this phenomenon is the low oscillation damping of the engine on the pylon under the wing. Therefore, research aimed at modernizing the engine mounting points on the pylon in order to reduce the level of elastic oscillations during aircraft operation seems relevant. One of the possible ways to solve this problem is to use the concept of a freed engine, when the engine attachment points to the pylon are modernized, providing more effective damping of engine oscillations. In order to confirm the possibility of practical implementation of these solutions, corresponding experimental studies were carried out on an experimental setup developed by the authors. A design of engine mounting units has been developed that allows specified displacements of the engine relative to the pylon during forced elastic oscillations of the system, which includes a hinged suspension, installation of additional elastic elements and hydraulic dampers.The article presents the results of studies of the influence of elastic-dissipative parameters (partial frequency of natural oscillations and partial decrement of oscillations) of an engine mount on an elastic pylon on the dynamic characteristics of the dynamic system “wing model – elastic pylon – engine”. It is shown that by introducing specially designed engine suspension units on pylons, it is possible to significantly change the dynamic characteristics (frequencies and amplitudes of natural oscillations) of the elastic system as a whole. Thus, the amplitudes of oscillations of the engine’s center of mass in the region of motor tones decrease by 3...7 times during forced harmonic oscillations.

Image fusion algorithm for the collaborative use of unmanned aerial vehicles

Currently, the applicable scope of unmanned aircraft application is increasingly expanding. The promising field of unmanned aircraft enhancement is the implementation of some collaborative actions during controlled flight. This paper considers some issues of the group application of unmanned aerial vehicles (UAV) related to the coordinated planning and control of UAVs performing surveillance missions. Performing aerial search operations is technically complicated by the requirement to recognize a search object in arbitrary conditions, which can be both simple and severe environment. The search area is limited by the UAV capabilities, so, in order to improve the efficiency of search operations, UAVs are combined into groups. An algorithm for solving the problem of object search in arbitrary conditions by a group of unmanned aircraft is proposed. The advantage of search by a group of unmanned aircraft is the coverage of the larger search area in a conventional unit of time. This paper addresses the unmanned aircraft configuration, containing both the means of collaborative flight operation and a synthetic vision system. The image obtained by the synthetic vision system is both a source of navigation information and a means which reliably determines the result of search operations. Depending on the conditions of search operations, the image obtained by the synthetic vision system may require additional processing to use as intended. A fusion algorithm is proposed, which is characterized by adaptive adjustment of parameters in each frame individually for different image fragments. Based on the results obtained, it is planned to create a new product for commercial operation of unmanned aircraft.

PELAYANAN STAF BOARDING GATE CITILINK BERDASARKAN MANAJEMEN ISLAM DI YOGYAKARTA INTERNATIONAL AIRPORT

This study aims to analyze the service of Citilink's boarding gate staff at Yogyakarta International Airport based on Islamic management. The research method used is qualitative with a case study approach. Data collection was conducted through interviews, observations, and documentation. The results show that Citilink's boarding gate staff at YIA are able to organize and manage boarding procedures quickly and efficiently, allowing passengers to board the aircraft on time without any hindrance. The staff's compliance with established SOPs is a major factor supporting passenger satisfaction. In addition to compliance with SOPs, other supporting factors in improving service quality include the availability of additional facilities that facilitate staff performance. However, this study also identifies several inhibiting factors, such as operational aircraft issues causing delays and passenger dissatisfaction with staff services. To address these obstacles, this study proposes several solutions, one of which is providing compensation to passengers in case of delays as a form of responsibility and fairness. In general, the service aligns with the principles of Islamic management, such as shiddiq (honesty), amanah (trustworthiness), tabligh (good communication), and fathanah (intelligence). However, there are still some aspects that need improvement, such as empathy and responsiveness in serving passengers.

Sensitivity analysis of urban air mobility aircraft design and operations including battery charging and swapping

Urban Air Mobility (UAM) is an evolving concept of passenger transportation providing on-demand flights within metropolitan environments, wherefore typically fully electric vertical take-off and landing aircraft are designed. Due to the underlying battery energy constraints, the design of UAM aircraft is very sensitive. Apart from the design considerations, the impact of aircraft operations on the entire UAM transport network must be examined. As there is no data from real-world operations available, this research article utilizes a system of systems simulation framework combining aircraft design with an agent-based simulation. The underlying approach offers the possibility of studying several parameters concerning UAM aircraft design and operations. In a case study focused on intra-city transport, aircraft design aspects regarding the payload capacity, the mission profile, and the reserve requirement are studied for a multirotor configuration. Furthermore, the aircraft operations aspects are focused on the turnaround procedures, the passenger demand, and the cruise speed. The multi-level sensitivity analysis ranging from the subsystem over the system of interest to the system of systems level allows us to trace the most sensitive aspects. Especially, the sensitivity analysis of battery fast-charging and swapping shows the importance of the holistic system of systems investigations for the successful development of UAM aircraft and services.

ИССЛЕДОВАНИЕ ПРОБЛЕМЫ УПРАВЛЕНИЯ ПОЖАРНЫМИ ПОДРАЗДЕЛЕНИЯМИ И РАЗРАБОТКА АЛГОРИТМА ПРИНЯТИЯ РЕШЕНИЙ РУКОВОДИТЕЛЕМ ЛИКВИДАЦИИ ЧРЕЗВЫЧАЙНОЙ СИТУАЦИИ ПРИ АВАРИИ ВОЗДУШНОГО СУДНА

This article discusses the problem of managing the emergency response process using the example of aircraft accidents. The mechanism of operation of fire and rescue units in extinguishing aircraft fires is investigated. The analysis of the origin of emergency situations of aircraft accidents has been carried out, on the basis of which the operations of aircraft operation in which the origin of emergency situations is statistically the most likely are determined. Based on the results of the analysis, typical situations of aircraft accidents are presented in the form of graph models. On these models, certain significant and critical situations are highlighted, divided by various aircraft operations. With the help of these graph models and the introduction into the system of dependence of the conducted rescue and other urgent work on the place of occurrence of an emergency, an algorithm was developed to support decision-making for the person responsible for coordinating units and conducting rescue and other urgent work related to the elimination of this kind of emergency situations, which reflects the full range of potential accidents that can happen to an aircraft. This algorithm can be used both for training the heads of fire and rescue units, and for creating emergency response techniques in case of aircraft accidents.

Uncertain process-based data integration and residual lifetime evaluation of PCB in airborne equipment with ADT and field data

Accurately evaluating the lifespan of the Printed Circuit Board (PCB) in airborne equipment is an essential issue for aircraft design and operation in the marine atmospheric environment. This paper presents a novel evaluation method by fusing Accelerated Degradation Testing (ADT) data, degradation data, and life data of small samples based on the uncertainty degradation process. An uncertain life model of PCB in airborne equipment is constructed by employing the uncertain distribution that considers the accelerated factor of multiple environmental conditions such as temperature, humidity, and salinity. In addition, a degradation process model of PCB in airborne equipment is constructed by employing the uncertain process of fusing ADT data and field data, in which the performance characteristics of dynamic cumulative change are included. Based on minimizing the pth sample moments, an integrated method for parameter estimation of the PCB in airborne equipment is proposed by fusing the multi-source data of life, degradation, and ADT. An engineering case illustrates the effectiveness and advantage of the proposed method.

Analysis method and experimental study of ice accumulation detection signal based on Lamb waves

A quantitative identification method for in-flight icing has the capability to significantly enhance the safety of aircraft operations. Ultrasonic guided waves have the unique advantage of detecting icing in a relatively large area, but quantitative identification of ice layers is a challenge. In this paper, a quantitative identification method of ice accumulation based on ultrasonic guided waves is proposed. Firstly, a simulation model for the wave dynamics of piezoelectric coupling in three dimensions is established to analyze the propagation characteristics of Lamb waves in a structure consisting of an aluminum plate and an ice layer. The wavelet transform method is utilized to extract the Time of Flight (ToF) or Time of Delay (ToD) of S0/B1 mode waves, which serves as a characteristic parameter to precisely determine and assess the level of ice accumulation. Then, an experimental system is developed to evaluate the feasibility of Lamb waves-based icing real-time detection in the presence of spray conditions. Finally, a combination of the Hampel median filter and the moving average filter is developed to analyze ToF/ToD signals. Numerical simulation results reveal a positive correlation between geometric dimensions (length, width, thickness) of the ice layer and ToF/ToD of B1 mode waves, indicating their potential as indicators for quantifying ice accumulation. Experimental results of real-time icing detection indicate that ToF/ToD will reach greater peak values with the growth of the arbitrary-shaped ice layer until saturation to effectively predict the simulation results. This study lays a foundation for the practical application of quantitative icing detection via ultrasonic guided waves.

ОСОБЛИВОСТІ ПРОЄКТУВАННЯ МЕХАНІЗАЦІЇ КРИЛА ЛІТАКІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

The paper analyses the methods of designing wing mechanisation for transport category aircraft. The wing layout with the placement of wing mechanisation means on the leading and trailing edges of the wing is analysed. Specific requirements for wing mechanisation units are considered. The analysis takes into account the requirements of aircraft operation, which provide easy access to inspect the mechanisation units and their attachment mechanisms. The need for constant monitoring of the synchronous operation of all mechanisation sections and ensuring their smooth movement is emphasised. The design of any type of mechanisation means involves the simultaneous solution of a number of development tasks: kinematic scheme, installation and control system, support structure and the device itself. In most cases, the drive mechanisms are also developed. The design of a new aircraft is a multi-stage iterative process that includes external design, development of a technical proposal, preliminary design, detailed design, production of prototypes, ground and flight tests, which determine the actual characteristics of the aircraft and the degree of its compliance with the technical specifications. Consider the advantages created by wing mechanisation equipment. The mechanisation of the AN-140 is considered as a representative of aircraft whose wings have trailing edge mechanisation but no leading edge mechanisation. The mechanisation of the AN-74 is also considered as a representative of aircraft that use two- or three-slotted retractable flaps, winglets or nose shields of large curvature over the entire wing span. The design technologies in integrated computer information systems are characterised, which allow to build a single process of computer modelling and engineering analysis and to conduct multivariate studies to select optimal design solutions in a sufficiently short time. A block diagram of the process of detailed design of flaps is proposed.

Variability of Index of Coalescence Activity (ICA) over a rain-shadow region during monsoon and its role in cloud seeding programs in India

The Index of Coalescence Activity (ICA) is an indicator of the microphysical state of the cloud. ICA is related to cloud base temperature and buoyancy of cloud at 500 hPa level. It is a useful parameter for making a decision on the type of seeding to be carried out. During Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) over the Indian region, aircraft operations for in situ measurements of aerosols and clouds were conducted from the base station Hyderabad to cover parts of north peninsular India falling under the rain-shadow region. Special Radiosonde flights were conducted in the afternoon hours prior to aircraft operations from the locations Hyderabad and Mahabubnagar in addition to regular India Meteorological Department (IMD) Radiosonde flights at 00 UTC from Hyderabad. The parameters like cloud base height and buoyancy at 500 hPa level obtained from Radiosonde flights have been used to estimate ICA values during the period of the experiment (June to October 2009–2011). The variability of ICA has been studied using morning and afternoon sounding profiles over the rain-shadow region. Morning hours showed highly negative ICA values, as compared to noon hours. During noon time, positive ICA values are observed before monsoon onset (in 2009, monsoon onset was 21st June over the study area) and on few occasions during post-monsoon (October). Positive ICA values represent that collision-coalescence (CC) process is not fully developed and hence, hygroscopic seeding is the proper decision. While, negative ICA values indicate active CC process, suggesting glaciogenic seeding. The soundings conducted just before the cloud seeding operations provide information about the actual thermodynamic and microphysical state of the cloud. Hence, ICA information is useful for providing guidelines to the operational cloud seeding programs.

Development of a Mini Weather Station Based on Rainboard and Android Applications in Cipageran Cimahi

Every airport necessitates a weather station to furnish crucial weather information for aircraft operations. However, not all airports possess adequate weather stations due to their high costs and susceptibility to damage. Consequently, both new and established small airports require weather stations. Thus, this study endeavors to develop affordable mini weather station equipment composed of cost-effective domestic components. Development and testing of this equipment tookplace in Cipageran Cimahi, representative of Indonesia's natural weather conditions. After conducting various tests, sufficient weather data was obtained, closely resembling actual weather station conditions. The hardware utilized comprises budget-friendly options such as Rainboard or Arduino Uno, paired with domestic component sensors. Data is displayed through Android-based applications and compared against calibration tools like "heles" and BMKG Info. While the sensor and calibration tool data exhibited symmetrical results, BMKG Info differed due to its broader coverage area, unlike the local weather measurements obtained by the sensors and calibration tools. Further refinement of this equipment can be achieved by employing superior sensor components and ensuring calibration.

Environmental Impact by Air Traffic: Assessing aircraft noise nearby Hong Kong International Airport

As part of a more global research effort towards a greener aviation, the present study focuses on the noise impact by aircraft operations around a major airport, namely the Hong Kong International Airport (HKIA). To assess a pre-existing aircraft noise prediction platform vis-à-vis the specificities of the local aviation scene, the ground noise impacts of 70+ aircraft flying in and out of HKIA are live-measured in two locations of Hong Kong city. This is achieved through in-situ audio recordings of aircraft during take-off/landing flight phases, along with a real-time tracking of their characteristics (aircraft and engine types, flightpaths, atmospheric conditions, etc.). Once suitably post-processed, the measurements are analyzed to characterize better the noise impacts by these various flights in regard to their specificities (e.g., aircraft types, flight operations). In a second stage, these noise impacts are compared against their digital twins, which are simulated via the noise prediction platform, using the actual flight characteristics (aircraft types, flightpaths, thrust, airspeed, etc.). This comparative assessment is achieved for a total of 60 flights consisting of 37 departures (resp. 23 arrivals) and involving 6 (resp. 5) aircraft types. Overall, the comparison between the field tests and their digital twins proves to be reasonably good, with both measured and predicted noise levels falling within a range of a few decibels across all flights, on average. Finally, specific analyses are conducted to explore the uncertainties weighing on the predictions, possibly explaining some of the mismatches observed between the experimental and computational results. Overall, the study further demonstrates that aircraft noise prediction methods such as the present one constitute a valuable means to assess the environmental impacts of air traffic operations, including when the latter are highly specific — as in Hong Kong city, owing to its complex airspace and meteorological conditions.

Detailed chemical analysis of soils and identification of priority pollutants on the territory of the state aviation airfield (Krymsk)

In connection with the intensification of military activities, environmental problems have worsened in large-scale territories. The primary task is to create lists of priority pollutants of environmental objects that are mandatory for control at landfills for various purposes, military bases, airfields. The paper presents the data of a detailed geochemical analysis of the soils of the state aviation airfield territory, on the basis of which priority contaminants were identified taking into account their gross content, hazard classes and the frequency of exceeding dangerous concentrations relative to the background. In the Krasnodar Territory (Krymsk), 32 samples from the territory of the state aviation airfield were analyzed over 4 years of research, and background concentrations of 22 metals, petroleum products, formaldehyde and nitrate nitrogen were also established. To determine the hazard classes of metals with unspecified maximum permissible concentrations, a correlation analysis was carried out comparing the hazard classes of substances and their clarks. Based on the results of the study, a list of pollutants recommended for control has been compiled including cesium, arsenic, scandium, niobium, lead (hazard class I); antimony, formaldehyde, nitrate nitrogen (II); petroleum products (III). The variability of the distribution of concentrations of pollutants on the airfield territory depends on the specifics of the operation of aircraft and special equipment for flight support. But at all sampling points (beginning – end, runway perimeter; taxiways; under the glide path), the main soil pollutant is arsenic, which concentrations exceed background concentrations by 16–36 times. The dangerously high content of petroleum products, formaldehyde, nitrate nitrogen, and scandium and caesium in some points in the airfield soils has been also found.

Full-Scale Evaluation of Airfield Pavement Runway Reconstruction with Full-Depth Reclamation Technique

Full-depth reclamation (FDR) has been identified as a strategic in-place recycling technique that is readily available for effecting a rapid restoration of the structural capacity of abandoned airfield pavements in contingency environments. A full-scale pavement section was designed to investigate the performance of pavement sections containing an FDR layer under simulated loading conditions of a tactical heavy aircraft. The FDR materials were composed of various combinations of base material types (i.e., gravel and limestone) and different asphalt layer thicknesses (i.e., 51 mm and 102 mm). The FDR blends were stabilized with a combination of 3% asphalt emulsion and 2% Portland cement. The FDR pavement section consisted of six different test items to investigate the performance of various FDR material types, asphalt layer thicknesses (i.e., 51 mm and 76 mm), and unpaved landing zones. The performance of the existing pavement and the FDR pavement test sections was compared to assess the improvements resulting from the rehabilitation of airfield pavements using the FDR technique. The results indicated that FDR was effective in restoring the structural condition of a damaged asphalt pavement section to support additional aircraft operations. The quality of the FDR blend had a significant impact on pavement performance, whereas the impact of the asphalt layer thickness was insignificant. Finally, the unpaved FDR sections also demonstrated enough structural competency to support a low volume of aircraft traffic before further surface layers are added during pavement reconstruction in contingency environments.

Impact monitoring of large size complex metal structures based on sparse sensor array and transfer learning

During aircraft operations, the impact events experienced by the aircraft may cause damage to the structure, thus posing a safety hazard. Therefore, an accurate determination of where the impact occurred and the time history of the impact force can provide an important basis for assessing the condition of the aircraft. However, modern aircraft structures are often large and complex, and relying on dense arrays of sensors for monitoring adds additional weight to the aircraft and reduces the economics of aircraft operation. This paper proposes a region-to-point monitoring strategy. First, a Convolutional Neural Network (CNN) model with region localization capability is trained using the sparse sensor array acquisition data. Then, the weighted center algorithm is used to determine the specific location where the impact occurs, in which the added fuzzy genetic algorithm can provide the ability to adjust weights to improve localization accuracy adaptively. As for the impact force prediction, this paper adopts a model based on a Convolutional Neural Network-Gated Recurrent Unit combined with a Squeeze-Excitation attention mechanism (CNN-GRU-SE), which is capable of predicting the impact force occurring in the flat plate and reinforced structure region of the aircraft under different energy conditions. Finally, the impact of incorporating a transfer learning approach on model performance and training cost is investigated for fuselage regions with different structures.

Characteristics of Volatile Organic Compounds Emitted from Airport Sources and Their Effects on Ozone Production.

In recent years, commercial air transport has increased considerably. However, the compositions and source profiles of volatile organic compounds (VOCs) emitted from aircraft are still not clear. In this study, the characteristics of VOCs (including oxygenated VOCs (OVOCs)) emitted from airport sources were measured at Shenzhen Bao'an International Airport. The results showed that the compositions and proportions of VOC species showed significant differences as the aircraft operating state changed. OVOCs were the dominant species and accounted for 63.17%, 58.44%, and 51.60% of the total VOC mass concentration during the taxiing, approach, and take-off stages. Propionaldehyde and acetone were the main OVOCs, and dichloromethane and 1,2-dichloroethane were the main halohydrocarbons. Propane had the highest proportion among all alkanes, while toluene and benzene were the predominant aromatic hydrocarbons. Compared with the source profiles of VOCs from construction machinery, the proportions of halogenated hydrocarbons and alkanes emitted from aircraft were significantly higher, as were those of propionaldehyde and acetone. OVOCs were still the dominant VOC species in aircraft emissions, and their calculated ozone formation potential (OFP) was much higher than that of other VOC species at all stages of aircraft operations. Acetone, propionaldehyde, formaldehyde, acetaldehyde, and ethylene were the greatest contributors to ozone production. This study comprehensively measured the distribution characteristics of VOCs, and its results will aid in the construction of a source profile inventory of VOCs emitted from aircraft sources in real atmospheric environments.

Deep learning reduces sensor requirements for gust rejection on a small uncrewed aerial vehicle morphing wing

Uncrewed aerial vehicles are integral to a smart city framework, but the dynamic environments above and within urban settings are dangerous for autonomous flight. Wind gusts caused by the uneven landscape jeopardize safe and effective aircraft operation. Birds rapidly reject gusts by changing their wing shape, but current gust alleviation methods for aircraft still use discrete control surfaces. Additionally, modern gust alleviation controllers challenge small uncrewed aerial vehicle power constraints by relying on extensive sensing networks and computationally expensive modeling. Here we show end-to-end deep reinforcement learning forgoing state inference to efficiently alleviate gusts on a smart material camber-morphing wing. In a series of wind tunnel gust experiments at the University of Michigan, trained controllers reduced gust impact by 84% from on-board pressure signals. Notably, gust alleviation using signals from only three pressure taps was statistically indistinguishable from using six pressure tap signals. By efficiently rejecting environmental perturbations, reduced-sensor fly-by-feel controllers open the door to small uncrewed aerial vehicle missions in cities.

Consensus-Based Merging and Spacing Method for Aircraft Self-Separation at Intersections

Within the context of delegating separation related tasks from an air traffic controller to the flight deck, this paper analyzes the merging and spacing problem for autonomous aircraft operations at busy airway intersections. A consensus-based control protocol is developed to achieve an ordered and safe traffic flow at a given intersection waypoint. Two primary implementation steps are covered in the protocol. In the first step, consensus on the target merging flow is achieved, where the merging stream is modeled as a straight line with the minimum total converging distance. In the second step, multiple aircraft with double-integrator dynamics and time-varying communication topologies are guided to merge into the target flow while maintaining appropriate interaircraft spacing. A state control law is designed, and the Lyapunov analysis method is leveraged to derive sufficient conditions on the communication topology and the control parameter for merging agents to reach consensus in finite time. Performance of the proposed method is evaluated through experimental simulations under different hypothetical scenarios in the two-dimensional plane.

Thrust Rebalance to Extend Engine Time On-Wing With Consideration of Engine Degradation and Creep Life Consumption

Abstract Over the years, airlines have consistently attempted to lower their operational costs and improve aircraft availability by applying various technologies. Engine maintenance expenses are one of the most substantial costs for aircraft operations, accounting for around 30% of overall aircraft operational costs. So, maximizing aircraft time between overhaul (TBO) is crucial to lowering the costs. The engine time on-wing is often limited due to the expiration of Life Limiting Parts, performance deterioration, etc. This paper presents a novel method of rebalancing the thrust of engines of an aircraft to maximize the time between overhaul of the aircraft considering the performance degradation and creep life consumption of the engines. The method is applied to a model aircraft fitted with two model engines similar to GE90-115B to test the feasibility of the method with one engine degraded and the other engine undergraded. The obtained results demonstrate that for the aircraft flying between London and Toronto with 5000 nominal flight cycles given to the engines, the time on-wing of the degraded engine could drop from 5000 to 2460 flight days due to its high-pressure (HP) turbine degradation (1% efficiency degradation and 3% flow capacity degradation), causing the same level of drop of time between overhaul of the aircraft. The time on-wing of the degraded engine could increase from 2460 flight days without thrust rebalance to 3410 flight days with thrust rebalance, i. e. around 38.6% potential improvement for the time between overhaul of the aircraft at the expenses of increased creep life consumption rate of the clean engine. The proposed method could be applied to other aircraft and engines.