Engine Stock Control Using the concept of U curve technique, it is delivering the best solution based on Aircraft on ground cost and holding and inventory cost of the engine
Breakeven analysis and route profitability, for SAH-BAH-SAH using A320 aircraft, in this article we define fixed cost, variable costs and revenue. A program is developed and a dynamic impact and effect of changing Fare, Distance, Capacity, and market demand will immediately reflects in final results in defining the breakeven point and minimum passengers required.
A Response Surface Based Wind Farm Cost (RS-WFC) model, is developed to evaluate the economics of wind farms. The RS-WFC model is developed using Extended Radial Basis Functions (E-RBF) for onshore wind farms in the U.S.. This model is then used to explore the in uence of di erent design and economic parameters, including number of turbines, rotor diameter and labor cost, on the cost of a wind farm. The RS-WFC model is composed of three parts that estimate (i) the installation cost, (ii) the annual Operation and Maintenance (O&M) cost, and (iii) the total annual cost of a wind farm. The accuracy of the cost model is favorably established through comparison with pertinent commercial data. Moreover, the RS-WFC model is integrated with an analytical power generation model of a wind farm. A recently developed Unrestricted Wind Farm Layout Optimization (UWFLO) model is used to determine the power generated by a farm. The ratio of the total annual cost and the energy generated by the wind farm in one year (commonly known as the Cost of Energy, COE) is minimized in this paper. The results show that the COE could decreasesigni cantlythroughlayoutoptimization,toobtainmillionsofannualcostsavings.
Breakeven analysis and route profitability, for SAH-BAH-SAH using A320 aircraft, in this article we define fixed cost, variable costs and revenue. A program is developed and a dynamic impact and effect of changing Fare, Distance, Capacity, and market demand will immediately reflects in final results in defining the breakeven point and minimum passengers required.
A Response Surface Based Wind Farm Cost (RS-WFC) model, is developed to evaluate the economics of wind farms. The RS-WFC model is developed using Extended Radial Basis Functions (E-RBF) for onshore wind farms in the U.S.. This model is then used to explore the in uence of di erent design and economic parameters, including number of turbines, rotor diameter and labor cost, on the cost of a wind farm. The RS-WFC model is composed of three parts that estimate (i) the installation cost, (ii) the annual Operation and Maintenance (O&M) cost, and (iii) the total annual cost of a wind farm. The accuracy of the cost model is favorably established through comparison with pertinent commercial data. Moreover, the RS-WFC model is integrated with an analytical power generation model of a wind farm. A recently developed Unrestricted Wind Farm Layout Optimization (UWFLO) model is used to determine the power generated by a farm. The ratio of the total annual cost and the energy generated by the wind farm in one year (commonly known as the Cost of Energy, COE) is minimized in this paper. The results show that the COE could decreasesigni cantlythroughlayoutoptimization,toobtainmillionsofannualcostsavings.
Case Study Of The Implementation Of Advanced Maintenance Techniques At Baa He...Andy_Watson_Sim
This case study highlights the history and the benefits bought about through improvements in maintenance planning and practice at BAA Heathrow Airport. Like other performance improvement practices, these changes saw some payback periods as low as one month based on minimum criteria only. Please contact me directly if you are interested in maintenance enhancements or go to www.simenergy.co.uk
Enhancements of Extended Locational Marginal Pricing – Advancing Practical Im...Power System Operation
Price formation is critical to efficient wholesale electricity markets that support reliable operation and efficient investment. The Midcontinent Independent System Operator (MISO) developed the Extended Locational Marginal Pricing (ELMP) with the goal of more completely reflecting resource costs and generally improving price formation to better incent market participation. MISO developed ELMP based on the mathematical concept of convex hull. However, considering the computational challenges and the existing market structure, MISO implemented an approximate version of ELMP. This paper presents enhancements to ELMP to bring the practical implementation of ELMP closer to the theoretical ideal and to achieve greater benefits of ELMP in production. The Special Ordered Set of Type Two (SOS2) piece-wise linear cost function formulation is used to tighten the approximation of, and under certain conditions exactly match, the convex hull of the cost function. Regulation commitment logic is also enhanced to maintain optimality under degeneracy conditions while providing flexibility for real-time regulation scheduling and pricing. Simulation results on the MISO system illustrate expected benefits. With the increasing interests in inter-temporal constraints, the on-going work on ELMP ramp modelling is also discussed.
This paper explores the effectiveness of the recently devel- oped surrogate modeling method, the Adaptive Hybrid Functions (AHF), through its application to complex engineered systems design. The AHF is a hybrid surrogate modeling method that seeks to exploit the advantages of each component surrogate. In this paper, the AHF integrates three component surrogate mod- els: (i) the Radial Basis Functions (RBF), (ii) the Extended Ra- dial Basis Functions (E-RBF), and (iii) the Kriging model, by characterizing and evaluating the local measure of accuracy of each model. The AHF is applied to model complex engineer- ing systems and an economic system, namely: (i) wind farm de- sign; (ii) product family design (for universal electric motors); (iii) three-pane window design; and (iv) onshore wind farm cost estimation. We use three differing sampling techniques to inves- tigate their influence on the quality of the resulting surrogates. These sampling techniques are (i) Latin Hypercube Sampling
∗Doctoral Student, Multidisciplinary Design and Optimization Laboratory, Department of Mechanical, Aerospace and Nuclear Engineering, ASME student member.
†Distinguished Professor and Department Chair. Department of Mechanical and Aerospace Engineering, ASME Lifetime Fellow. Corresponding author.
‡Associate Professor, Department of Mechanical Aerospace and Nuclear En- gineering, ASME member (LHS), (ii) Sobol’s quasirandom sequence, and (iii) Hammers- ley Sequence Sampling (HSS). Cross-validation is used to evalu- ate the accuracy of the resulting surrogate models. As expected, the accuracy of the surrogate model was found to improve with increase in the sample size. We also observed that, the Sobol’s and the LHS sampling techniques performed better in the case of high-dimensional problems, whereas the HSS sampling tech- nique performed better in the case of low-dimensional problems. Overall, the AHF method was observed to provide acceptable- to-high accuracy in representing complex design systems.
An integrated OPF dispatching model with wind power and demand response for d...IJECEIAES
In the day-ahead dispatching of network-constrained electricity markets, renewable energy and distributed resources are dispatched together with conventional generation. The uncertainty and volatility associated to renewable resources represents a new paradigm to be faced for power system operation. Moreover, in various electricity markets there are mechanisms to allow the demand participation through demand response (DR) strategies. Under operational and economic restrictions, the operator each day, or even in intra-day markets, dispatchs an optimal power flow to find a feasible state of operation. The operation decisions in power markets use an optimal power flow considering unit commitment to dispatch economically generation and DR resources under security restrictions. This paper constructs a model to include demand response in the optimal power flow under wind power uncertainty. The model is formulated as a mixed-integer linear quadratic problem and evaluated through Monte-Carlo simulations. A large number of scenarios around a trajectory bid captures the uncertainty in wind power forecasting. The proposed integrated OPF model is tested on the standard IEEE 39-bus system.
Two models are present, the first is point to point model and demonstrated the minimizing cost issue, while the other model is Multi-stops operating model, and it is addressing profit maximization.
TES Aviation Group is one of the world's foremost providers of aircraft engine asset management services. TES manages a client portfolio of aircraft engines valued in excess of $3.5 billion and offers an integrated management solution providing engineering services, aircraft engines for lease, as well as a broad range of aircraft engine parts.
The team is developing business relationships within the Aerospace community to establish an OEM Repair Center for manual pocket doors, sidewall & pedestal tables.
We seek affiliation with VIP design authorities and system integrators
Check Interval Escalation, this is a hard topic for airlines, it mostly deliver and governed by aircraft manufactures, it needs a strong back ground in statistics, but it has a great impact on maintenance cost, and it is not widely familiar and implemented in the airline industry.
this is head to head study for aircraft evaluation and selection, it address, value analysis, cost per trip vs cost per seat, U curve techique, and optimum operating curve
Case Study Of The Implementation Of Advanced Maintenance Techniques At Baa He...Andy_Watson_Sim
This case study highlights the history and the benefits bought about through improvements in maintenance planning and practice at BAA Heathrow Airport. Like other performance improvement practices, these changes saw some payback periods as low as one month based on minimum criteria only. Please contact me directly if you are interested in maintenance enhancements or go to www.simenergy.co.uk
Enhancements of Extended Locational Marginal Pricing – Advancing Practical Im...Power System Operation
Price formation is critical to efficient wholesale electricity markets that support reliable operation and efficient investment. The Midcontinent Independent System Operator (MISO) developed the Extended Locational Marginal Pricing (ELMP) with the goal of more completely reflecting resource costs and generally improving price formation to better incent market participation. MISO developed ELMP based on the mathematical concept of convex hull. However, considering the computational challenges and the existing market structure, MISO implemented an approximate version of ELMP. This paper presents enhancements to ELMP to bring the practical implementation of ELMP closer to the theoretical ideal and to achieve greater benefits of ELMP in production. The Special Ordered Set of Type Two (SOS2) piece-wise linear cost function formulation is used to tighten the approximation of, and under certain conditions exactly match, the convex hull of the cost function. Regulation commitment logic is also enhanced to maintain optimality under degeneracy conditions while providing flexibility for real-time regulation scheduling and pricing. Simulation results on the MISO system illustrate expected benefits. With the increasing interests in inter-temporal constraints, the on-going work on ELMP ramp modelling is also discussed.
This paper explores the effectiveness of the recently devel- oped surrogate modeling method, the Adaptive Hybrid Functions (AHF), through its application to complex engineered systems design. The AHF is a hybrid surrogate modeling method that seeks to exploit the advantages of each component surrogate. In this paper, the AHF integrates three component surrogate mod- els: (i) the Radial Basis Functions (RBF), (ii) the Extended Ra- dial Basis Functions (E-RBF), and (iii) the Kriging model, by characterizing and evaluating the local measure of accuracy of each model. The AHF is applied to model complex engineer- ing systems and an economic system, namely: (i) wind farm de- sign; (ii) product family design (for universal electric motors); (iii) three-pane window design; and (iv) onshore wind farm cost estimation. We use three differing sampling techniques to inves- tigate their influence on the quality of the resulting surrogates. These sampling techniques are (i) Latin Hypercube Sampling
∗Doctoral Student, Multidisciplinary Design and Optimization Laboratory, Department of Mechanical, Aerospace and Nuclear Engineering, ASME student member.
†Distinguished Professor and Department Chair. Department of Mechanical and Aerospace Engineering, ASME Lifetime Fellow. Corresponding author.
‡Associate Professor, Department of Mechanical Aerospace and Nuclear En- gineering, ASME member (LHS), (ii) Sobol’s quasirandom sequence, and (iii) Hammers- ley Sequence Sampling (HSS). Cross-validation is used to evalu- ate the accuracy of the resulting surrogate models. As expected, the accuracy of the surrogate model was found to improve with increase in the sample size. We also observed that, the Sobol’s and the LHS sampling techniques performed better in the case of high-dimensional problems, whereas the HSS sampling tech- nique performed better in the case of low-dimensional problems. Overall, the AHF method was observed to provide acceptable- to-high accuracy in representing complex design systems.
An integrated OPF dispatching model with wind power and demand response for d...IJECEIAES
In the day-ahead dispatching of network-constrained electricity markets, renewable energy and distributed resources are dispatched together with conventional generation. The uncertainty and volatility associated to renewable resources represents a new paradigm to be faced for power system operation. Moreover, in various electricity markets there are mechanisms to allow the demand participation through demand response (DR) strategies. Under operational and economic restrictions, the operator each day, or even in intra-day markets, dispatchs an optimal power flow to find a feasible state of operation. The operation decisions in power markets use an optimal power flow considering unit commitment to dispatch economically generation and DR resources under security restrictions. This paper constructs a model to include demand response in the optimal power flow under wind power uncertainty. The model is formulated as a mixed-integer linear quadratic problem and evaluated through Monte-Carlo simulations. A large number of scenarios around a trajectory bid captures the uncertainty in wind power forecasting. The proposed integrated OPF model is tested on the standard IEEE 39-bus system.
Two models are present, the first is point to point model and demonstrated the minimizing cost issue, while the other model is Multi-stops operating model, and it is addressing profit maximization.
TES Aviation Group is one of the world's foremost providers of aircraft engine asset management services. TES manages a client portfolio of aircraft engines valued in excess of $3.5 billion and offers an integrated management solution providing engineering services, aircraft engines for lease, as well as a broad range of aircraft engine parts.
The team is developing business relationships within the Aerospace community to establish an OEM Repair Center for manual pocket doors, sidewall & pedestal tables.
We seek affiliation with VIP design authorities and system integrators
Check Interval Escalation, this is a hard topic for airlines, it mostly deliver and governed by aircraft manufactures, it needs a strong back ground in statistics, but it has a great impact on maintenance cost, and it is not widely familiar and implemented in the airline industry.
this is head to head study for aircraft evaluation and selection, it address, value analysis, cost per trip vs cost per seat, U curve techique, and optimum operating curve
Determination Inventory Level for Aircraft Spare Parts Using Continuous Revie...Waqas Tariq
In this paper, we determine ordering quantity and reorder point for aircraft consumable spare parts. We use continuous review model to propose a spare part inventory policy that can be used in a aircraft maintenance company in Indonesia. We employ ABC classification system to categorize the spare parts based on their dollar contribution. We focus our research on managing the inventory level for spare parts on class A and B which commonly known as important classes. The result from the research indicates that the continuous review policy gives a significant amount of saving compared to an existing policy used by the company.
This is a network analysis addressing yemenia network, considering SANAA as the main hub of the airline, it use U curve, and developing optimum operating curve for yemenia - yemen airways
The term overbooking is usually related with the reservation system of an airline, which means booking a number of passengers
than the offering capacity of the aircraft, to minimize the effect of no-show passengers percentage, as this no-show is in the last
minute before takeoff of the flight means losing a secure revenue to be earned and losing seats that can be utilized or resold for
that same flight, so the process is a balancing between the two terms overbooking and no-show, the income of the first compensate
the lose caused by the second.
Periodic Review Model for Determining Inventory Policy for Aircraft Consumabl...Waqas Tariq
This research is conducted to develop inventory policy of aircraft consumable spare parts which are needed on aircraft maintenance activity . In this research, we used periodic review model to determine the optimal policy of aircraft spare parts inventory. By using the periodic review model, we find optimal period of inventory review and maximum level of inventory. The optimal decision is determined based on the minimum total cost. We have classified consumable spare parts using ABC method to categorize them based on their dollar contribution and demand frequency. Therefore in this research, we focus on managing the inventory level for spare parts on class C. The result from this study shows that the proposed periodic review policy result in lower total inventory cost compared the the company policy. The proposed policy gives an average saving 35.38 %.
Allocate the right aircraft capacity, it is new approach , addressing, Rask and cask or catk, by using the concept of U curve technique, for two costs , i.e cost of offering seat and cost losing the opportunity, resulting in right capacity and optimum frequency
PREDICTION OF REPAIR & MAINTENANCE COSTS OF DIESEL ENGINEijmech
Diesel engine is widely use for different applications, the failure frequency of diesel engine is more increase to increase the age & use of engine in order to take decision to replacement of engine on the basis of Repair & Maintenance cost (R&M) & predication of future Repair & Maintenance costs of diesel engine used in Borewell compressor. Present case study discusses prediction of accumulated R&M costs (Y) of Diesel engine against usage in hours (X). Recorded data from the company service station is used to determine regression models for predicting total R&M costs based on total usage hours. The statistical results of the study indicates that in order to predict total R&M costs is more useful for replacement
decisions than annual charge.
Breakeven analysis and route profitability, for SAH-BAH-SAH using A320 aircraft, in this article we define fixed cost, variable costs and revenue. A program is developed and a dynamic impact and effect of changing Fare, Distance, Capacity, and market demand will immediately reflects in final results in defining the breakeven point and minimum passengers required.
Developing a Programme for Engine Design Calculations of a Commercial AirlinerIJMER
This project leads to a path of understanding the necessary fundamental calculations that
need to be done during an engine design of a commercial airliner. These calculations are hand based
calculations that are done based on the parameters of the airframe data provided by the airline
manufacturers. These calculations are a little tedious and require a paper and a pen to carry out the
procedures. This project will enable the following outcomes for the students: providing a fundamental
understanding of the aircraft engine design, more from the grounds up approach and an automated way
(program) of doing the above, enabling faster iterations and making it easy to achieve the required
parameters for designing an engine
Airline Start up is hard issue for investors, today airline try to survive in this high competitive industry, this presenting address new tools that guide and put airline in the right way
Engine PR MRs are crucial in aircraft leasing. They are the highest dollar item of monthly MR invoices. For older aircraft (around 15 years or older) the engine PR MRs can translate into a monthly expense higher than the Basic Rent itself.
As MR Rates depend on highly unpredictable SV Costs and MTBRs, this is usually an item heavily negotiated while agreeing on aircraft Leases. It is an area where the technical and legal teams from both the airline (lessee) and lessor need to work cooperatively to ensure smooth management of Engine PR MRs during the lease.
Finally, the economics of a leasing deal (for both the lessor and the lessee) depend greatly on the level of Engine PR MRs. In fact, this is typically a factor that has a significant effect while agreeing on the value of an aircraft that is being sold while on lease.
TINCE2016 - Impact load curve for commercial aircrafts: a normalized model – ...Gildas POTIN
Safety requirements of nuclear new built projects have been considered airplane crash (APC) hazards for many years, but mostly regarding general and military aviation. Since 09/11 events, the need to assess the risk of commercial APC has been highlighted. Consequently, national and international organizations began to develop guidelines to support regulators, designers and owners of the plants with respect to the commercial APC analysis. Furthermore, some regulators position is changing, because new requirements make this load case no longer limited to malicious acts, but also for accidental situations (e.g Turkey).
Many papers presented some load time functions, using simplified methods to complex dynamic finite element calculations. Various types of aircraft were studied at different speeds. The very first work in 1968, for the B707-320 and B720 aircrafts, resulted in the recognized Riera method. Then, some other load curves were issued such as A320, B767 and B747. All these methods have common disadvantage that they need to collect detailed data about one given aircraft for each project, such as the mass distribution, the crush force, or complete finite element models. On the contrary, the Turkish regulator defines APC load case by only two single parameters (total mass and speed), although no simple formula exists in design codes.
After inventory of a large range of commercial aircraft characteristics and public load curves, this paper defines a universal normalized formula for the APC load as function of the mass and the speed. Besides, a reduction factor for spent kerosene before crash is proposed.
Fleet Repositioning is about Assigned the Right Aircraft to the Right Route, it is implemented for two airlines case models, First point to point operation model – minimizing cost – Yemenia as a hub and the second is multi-stops operating model – maximizing profit – route SAH-DXB-KUL-JKT , it also address competitive analysis for Yemenia position in the market by using BCG matrix with respect with its competitors.
Airport Forecasting, is a collection articles which published in CAMA magazine, most of the airports of the world are forecasted, by using a new concept, and approach i.e Max/Min signal tracking approach, while the accuracy of the model is addressing by mapping to main elements – Displacement and Rotational in the accuracy matrix. Hope to enjoy !
These articles published in CAMA, having the following titles 1- Accuracy of Forecasting Model (Coefficient of Determinations vs. Signal Tracking ) 2- Head To Head Analysis, A320 Family VS B737NG (Value Analysis) 3- Forecasting by Objectives ( Airport Forecasting ).
Overbooking policy for airline is one of the main channels that enhance revenue and improve profit; it should be carefully implemented to avoid any negative effects of denied boarding impact especially on the brand name for the airline. It should be address the best strategy that minimize cost between no-show cost and denied boarding cost, by implement cost based overbooking model ( U curve technique )
This is a hard task for airlines, it just done only by manufactures, it is complicated topic, and need a huge efforts from all. Maintenance, Distributions, test, analysis, statistics,
1. study
STOCK
CONTROL FOR
ENGINES OF
AIRCRAFT
Eng. Mohammed S. Awad
PhD candidature – Aviation Management
The number of engines in stock has a
significant role in deciding the technical
budget for any airline. This has a direct
effect or impact on the overall budget of the
airline. Due to the expansive values of these
engines, purchasing engines that exceeds
the actual company level needs; it affects
the maintenance and holding costs and
the money seized by these extra engines
can be utilized in other useful project.
Nevertheless a number of engines less than
the required service level exposing the airline
to huge loss or risk of losing revenue. Due
to unavailability of engine, such a term as
Aircraft On Ground Cost (AOG) is used to
reflect a loss of revenue. While optimization
techniques are usually used to solve such
a problem, to define the right number of
engine in stocks, by an analysis of U curve
cost analysis. While previously many airlines
work on 1:1 inventory policy for engines
in stocks and numbers of engine of the
fleet, which is a very expensive policy.8
16
2. study
Study
Pic. No. 1 Fig. No.1
Introduction B) Cost of losing Opportunity expressed by curve C. That take
The important policy of material This cost is demonstrated by a U curve shape, and the lowest
planning division in airline AOG cost – Aircraft On Ground value in the curve demonstrate
companies is to find the right Cost, which arises due to loss of the best decision to be selected.
number of spare parts in the stock revenue since no supported engine Actually the B curve can
which subsequently assists and / available engine in stock as shown be presented by a well-
supports maintenance program in figure (2). So the decision to known statistical distribution
of the airlines. So spare part allocate the right number of spare that reflects the best defects
availability has an important role in engines depends on the minimum behavior of an Engine.
maintaining the operation activity costs of the pre-mentioned
of the fleet and drive the operating parameters. Thus airlines should Poisson distribution
system at high performance. select the right policy that reflects According to the method of
According to the situation, minimum costs. By referring to analysis and a data sampled, a
position and related costs, the the figure (2), the straight line (A) proper distribution is selected.
right stock policy is selected. reflects the increasing cost due to In a statistics a two terms are
Spare parts should be typically / the increasing number of engine. used widely, i.e. time and event
fit, otherwise this policy will be more While the curve B reflects the that may describe the distribution
expansive to support the fleet. gradual decline of AOG Cost of more clearly, also distribution
And there several questions the aircraft. So by increasing the can be continuous or discrete.
should answer clearly as is number of engines in spare, we In our case, Poisson Distribution
there any indication / guide line are expected to minimize the cost represents the best distribution
to indicate that policy?, is that incurred by Aircraft On Ground that reflect the defect characters
policy economic? And what is Cost. The total resulting cost will in terms of engine demand and
the required service level to be be the super imposed of these it’s a specified period of time.
implemented to that spare parts two curves (Functions), which
policy, and how far the repair Estimating the Parameters
and overhaul cost compared to of Poisson distribution
the breakdown cost, and AOG The main parameter of Poisson
(Aircraft On Ground) Cost. Also distribution is expressed by the
are these long-term decisions for total time of the experiments by the
overhaul and replacement issues?, average time the events (defects)
where these topic are usually to happen and can be expressed in
related to U curve techniques. the following equation
U Curve Technique: ^ Total Opreating Time of the Engines
n =
U curve techniques are Average life time of Engines
illustrated by two main factors
Fleet Size × No. of engines in A/C ×
A) Cost Of Offering Service Daily Ultilization × repair Cycle
B) Cost Of Losing Opportunity ^
n = Main Time To Failure
As shown in figure (1) ............. Equation (1)
A) Cost Of Offering Service: Engine PW 4000 (94 inch)
In this case, the cost The Engine PW 4000 (94 inch) is
demonstrated by the ownership one of most world wide commercial
and holding cost (maintenance), engines, it is supported and installed
mathematically, is a linear function in both fleet of Boeing or Airbus, as
represented by a straight line. B747-400, B767-200/300, MD11,
A300-600, A310-300
Figure below shows engine
PW 4000 in a test. 8
17
3. study
Case Study Table No.1 Inputs
Inputs air bus 310-300
As shown in table (1) the basic
input data
inputs for the analysis as No of
Aircraft, No of Engine , Daily fleet Size 3
Utilization in hours and Repair Cycle OTY oer aircraft 2
by Days and MTBF by manufacture. daily utiliation (HRS) 9
repair cycle (days) 120
Analysis
By implementing U curve techniques MTBD (hours) 10,000
and developing a spread sheet estimationg (poisson) 0.648
of Excel program and using the AOG coast (USD) 100,000
assumption mentioned in table
engine holding cost 2000
(1) and also assuming the failure
distribution is equivalent to the
demand distribution of engines, the Table No.2 Analysis
process is an engine replacement
while the event of failure will occur in
the mid period, all these assumption
reflect best distribution is Poisson.
The calculation is demonstrated by
equation (1) and a Poisson function
implemented from Excel program. So
we evaluate the probability of Engine
failure, and AOG cost as it is shown in
tables (2). The study shows the best
decision is to keep 2 engines in stock.
Effect of Fleet Size On Spare Engines
Referring to the previous study,
let us keep all the pre-mentioned
parameters while the Fleet Size factor
is random variable, as step function,
so multiple U curve are developed
based on the different values of
fleet size as shown in the following
graph, which can represented by a Fig. No.2 U Curve Approach
smooth line with R2= 0.94, so with
AOG
a fleet size of 12-15 Aircraft the
required number will be 5 Engine HOLDING
in stock as shown in Fig (3).
TOTAL
Cost (USD)
Summary
The setting policy, for decided
number of engines in stock, is a
main economic approach to minimize
the cost in aviation industry, due
to the highest purchasing price of
engines. While many arrangements
and policies are setup to minimize
the cost of inventory and cost of
AOG (Aircraft On Ground Cost) by Numbers of Spares Engine
using Poisson Distribution, which
is a statistical tool used / reflects Fig. No.3 Relations of Fleet Size & No. of Engines for Airlines
the failures patterns / and inventory
environments in airline industry.
So all parameters are considered
No. of Engines in Stock
as number of aircrafts, number
of engines in each aircraft, daily
utilization, repair cycle in days, and
average life of the engine i.e (MTTF)
to develop U curve optimum cost
to select the right quantity of spare
engines in stocks based on two
costs – holding cost and AOG cost.
Further we can study all the
input factors and their effects on
inventory of the company as repair
cycle and daily utilizations. n Fleet Size (No. of Aircraft)
18
4. Civil Aviation & Meteorology Authority, July - September 2010, issue 8
www.camamagazine.com