Engine Wash Research Articles

An Assessment of the Economic Viability of Engine Wash Procedures on the Lifecycle Costs of an Aircraft Fleet.

Aircraft operators find themselves in a highly complex and competitive environment in which the economic pressure on companies is constantly increasing. In addition, annual air traffic is expected to increase by 4-5% (despite the Covid-19 pandemic), which requires significant improvements of aircraft efficiency. To address this on European and global scale, long-term economic and ecologic goals have been defined in the "Flightpath 2050" by the European Commission. One way to reduce both operating costs and environmental impact is to reduce aircraft fuel consumption. Regularly performed engine washes can reduce the accumulation of dirt and debris in the engine and partially restore the performance degradation as well as lower the wear and tear of the engine. This results in lower exhaust gas temperature and a slower aging engine with longer intervals between required maintenance events. 
 Most engine wash studies have drawn their system boundary around the engine and consider only the one-time improvements that result from a wash. Long term effects that build on these improvements, such as changes in maintenance and replacement cycles, are usually not considered. Few studies are available that extend their system boundary and consider changes in maintenance costs. Yet the value of engine wash processes is often quantified on an insufficient setting, especially when environmental conditions and fleet effects are neglected. To estimate the overall benefit and assess the impact on lifecycle costs, a full evaluation of engine wash within an entire fleet is required and fleet effects such as the possibility of downrating the engine for a smaller aircraft should be considered. 
 The aim of this work is to quantify the true value of engine wash procedures considering both physical constraints as well as operational fleet wide considerations. Using discrete event simulations at fleet level, a detailed investigation of the primary and secondary effects and a quantification of lifecycle costs will be performed. Particular attention will be paid to the influence on maintenance costs as well as the economic effect of increased time on wing. With the help of an improved environmental modeling and with the consideration of fleet effects, a holistic statement is possible.
 To investigate this problem, a lifecycle costing method, named LYFE, developed by DLR will be used. LYFE uses discrete event simulation to model the product lifecycle from order to operation until disposal of an aircraft fleet. For this analysis the tool will be extended to separate the lifecycles of the engines and those of the aircraft, so the engines can change the aircraft and the downrating of the engine for a smaller aircraft can be modeled. In order to represent the contamination and the performance degradation of the engines as realistically as possible, data on the outside air temperature, dust, pollution and other particles in certain regions at the various airports are also included in the tool. Furthermore, the option of derating the engine’s thrust is considered. The lifecycle of two different fleets will be simulated and studied. The difference between the two fleets is that the baseline fleet does not perform any engine washes, while the study fleet performs engine washes. Both fleets consist of different types of aircraft, so that downrating of the engines is possible and the entire lifecycles of the aircraft can be mapped. The evaluation follows two approaches: firstly, the engine wash is carried out and examined regularly; secondly, the intervals at which the engine wash is carried out are optimized in such a way that the lifecycle costs of the fleet are as low as possible. In both cases the number of engines necessary to operate the fleet will be the basis for an overall statement.
 With this holistic view of how engine washes within a fleet affect its lifecycle costs, a much more realistic statement about this on-wing maintenance action is possible.

Fuel savings model after aero-engine washing based on convolutional neural network prediction

In order to accurately calculate the fuel savings after aero-engine washing, therefore the engine cleaning process flow can be arranged more scientifically and reasonably. In this paper, a derivation method of fuel savings model after engine washing based on delta fuel flow (DFF) degradation baseline and convolutional neural network prediction technology is proposed. Firstly, the fuel savings model of cruise phase is established based on gas path parameters related to the engine fuel consumption, and the QAR data’s trend on entire flight is mined, and the regularity of the gas path parameters in the cruise phase is extended to the entire flight, thereby the fuel savings model after engine washing of whole Flight is derived. In the model derivation process, the unwashed engine’s DFF degradation baseline after the wash point is predicted. According to the characteristics of DFF discrete time series, a discrete input process neural network prediction model based on discrete data convolution operation is established. The convolution operation of discrete data is used to replace the integral operation of continuous function, which effectively avoids the loss of fitting precision caused by the smooth processing of discrete time series data before the input of the process neural network model, and improves the prediction accuracy of discrete time series data. A denoising method combining Singular Value Decomposition (SVD) and Empirical Mode Decomposition (EMD) is used to denoise the DFF before and after engine washing, and the trend analysis method is used to solve the intersection of the unwashed state engine’s DFF degradation baseline and washed state engine’s DFF degradation baseline, thereby the washing effect cycle numbers is predicted, and in which the total fuel savings model of whole fleet after engine washing is derived by accumulating every flight fuel savings. The post-washed engine fuel saving calculation of an airline is used as a verification experiment. The results show that post-washed engine fuel saving prediction model presented in the paper is the closest to the actual fuel savings model.

Fuel and emission reduction assessment for civil aircraft engine fleet on-wing washing

On-wing washing for civil aviation engine is an important approach to improve the Exhaust Gas Temperature Margin (EGTM), and to reduce the fuel consumption as well as the resultant aviation emission. In view of the fuel flow reduction achieved by on-wing washing, this study proposes an estimation method of engine performance improvement due to washing according to fleet fuel consumption savings and engine washing costs. Finally, the engine washing interval of a fleet can be optimized based on the proposed performance assessment method of on-wing washing. A case study of one airline fleet of 200 CFM56 Engines demonstrates the effectiveness of the proposed method. The results show that the optimal washing interval is 3 times a year, and that an average annual cost savings of 20.15 million dollars can be achieved by reducing 5471 ton fuel consumption and 17,250 ton CO2 emission.

Selected aspects of the technological processes of the aircraft engine washing

In production, treatment or operation of selected components it is not possible to avoid dirtiness. Given the fact that impurities significantly affect the quality, functionality and service life of a part, the surface preparation of such an element is a key aspect in the regeneration process. The choice of contaminant removal method will depend on the type of impurity. This operation is often treated as a separate technological process, during which the type and properties of the removed dirt are determined, along with assessing the degree of purity required to ensure the correctness of subsequent operation or operations. Rising expectations regarding specific effects of purification have led to massive improvement of traditional methods, and development of new processes that require the use of complex technologies. The present research was to prepare the technological process of washing selected parts of the aircraft turbine engine. The preliminary assumption was to use the LUA-1000 automatic washing processing line, which selecting and modifying particular parameters of the process in order to comply with the technological assumptions. The elaborated process includes the following stages: preparing the selected parts for washing, washing the engine parts and the quality control of washing. The primary objective of the study was to achieve the most beneficial parameters possible and, at the same time, to minimise the costs of the machine’s work, as well as to preserve high quality and to comply with environmental standards.

Efficiency of sugarcane bagasse-based sorbents for oil removal from engine washing wastewater.

This work evaluates the efficiency of sugarcane bagasse-based sorbents in the sorption of oil from engine washing wastewater. The sorbents were obtained from sugarcane bagasse in the natural form (SB-N) and modified with either acetic anhydride (SB-Acet) or 3-aminopropyltriethoxysilane (SB-APTS). The results showed that the sorption capacity of these materials decreased in the following order: SB-APTS > SB-N > SB-Acet. The superior oil sorption capacity observed for SB-APTS was attributed to the polar amino end groups in the silane structure, which acted to increase the hydrophilic character of the fibers. However, all the sorbents obtained in this study were able to clean a real sample of wastewater from engine washing, leading to significant reductions in suspended matter, sediment, anionic surfactants, and turbidity.

Recoverable Versus Unrecoverable Degradations of Gas Turbines Employed in Five Natural Gas Compressor Stations

Gas turbines (GT), like other prime movers, experience wear and tear over time, resulting in decreases in available power and efficiency. Further decreases in power and efficiency can result from erosion and fouling caused by the airborne impurities the engine breathes in. To counteract these decreases in power and efficiency, it is a standard procedure to “wash” the engine from time to time. In compressor stations on gas transmission systems, engine washes are performed off-line and are scheduled in such intervals to optimize the maintenance procedure. This optimization requires accurate prediction of the performance degradation of the engine over time. A previous paper demonstrated a methodology for evaluating various components of the GT gas path, in particular, the air compressor side of the engine since it is most prone to fouling and degradation. This methodology combines gas path analysis (GPA) to evaluate the thermodynamic parameters over the engine cycle followed by parameter estimation based on the Bayesian error-in-variable model (EVM) to filter the data of possible noise due to measurement errors. The methodology quantifies the engine-performance degradation over time, and indicates the effectiveness of each engine wash. In the present paper, the methodology was extended to assess both recoverable and unrecoverable degradations of five GT engines employed on TransCanada's pipeline system in Canada. These engines are: three GE LM2500+, one RR RB211-24G, and one GE LM1600 GTs. Hourly data were collected over the past 4 years, and engine health parameters were extracted to delineate the respective engine degradations. The impacts of engine loading, site air quality conditions, and site elevation on engine-air-compressor isentropic efficiency are compared between the five engines.

EcoPower to the people

Over the last few years, much attention has been paid to the declining service by airlines. No longer providing meals, additional luggage fees, and the 3 oz. liquid container rules have made flying an increasingly stressful experience. As the experience for passengers has become more complicated, the airlines have found a simplified solution for one task- washing their engines -thanks to EcoPower engine wash. EcoPower service uses only atomized water to wash the engines of commercial and military aircraft. Produced by Pratt & Whitney, the benefits of this fairly recent development are numerous: reductions in fuel burn and carbon dioxide emissions, subsequent cost savings, less water usage, no hazardous chemical runoff, and speedy service, requiring only 45 minutes to an hour for the wash, as opposed to the four to six hours required by other methods.

Determining compressor wash programmes for fouled gas turbines

An assessment on the impact of compressor fouling over gas turbine thermodynamic and economic performance is presented. This operational problem is dependent on engine location as it is caused by airborne particles dragged into the engine by the compressor. For the most hazardous locations, performance deterioration can reach 10 per cent/month for power and 5 per cent/month for efficiency, with respect to rated values. Engine washing is required to compensate for these losses. Different approaches made by relevant authors in the past are analysed, showing big contradictions in predicting sensitivity to fouling of engines with different sizes and specifications. This adds complexity to establishing washing programmes based on engine specifications rather than engine location. The conclusion is that a tailored washing schedule must be developed through a trial and error methodology, which is very dependent on the operator's experience with similar engines. These concepts are applied to evaluate the performance of a running engine with severe fouling. The impact of hourly variation of electricity price and length of washing on the cashflow of a plant incorporating compressor is assessed, along with an evaluation of the effect of adopting a washing schedule which is far from the optimal or close to it.