Patent Application
20060224482
The present invention relates generally to a technique for managing an asset inventory and, more particularly, to methods and systems for managing a spare engine inventory for a fleet of aircrafts.
Various service organizations establish long-term contractual agreements with their customers, contracting to provide a broad scope of services for a given term. For example, engine services organizations often establish long-term service agreements (LTSA's) with airlines to provide most maintenance requirements for the engines of an airline's fleet. Thus, if an engine requires maintenance or repair during the contractual term, the LTSA requires the service organization to properly address such issue. Unfortunately, repairing or maintaining an engine often requires taking the engine off-line and grounding the associated aircraft. Indeed, maintenance may require shipping the engine off-site to a maintenance facility with a turn around time of three-months or so, for example.
Accordingly, LTSA's generally require that the service organization maintain an inventory of spare engines, ensuring availability. In some cases, the LTSA also requires the airline to maintain an inventory of spare engines as well. Maintaining an inventory of engines is an expense to the service provider and/or the airline. If too many spare engines are maintained, necessary capital can be tied-up. By contrast, if too few spare engines are available, the service provider or airline may be forced to lease the necessary engines from a third-party, generally at premium. In certain cases, a spare engine may not be available, leading to contractual penalties, for instance.
Therefore, there is a need for an improved technique for managing an asset inventory. Particularly, there is a need for systems and methods that reduce the total cost of maintaining the asset inventory.
In accordance with one exemplary embodiment, the present technique provides a method of managing an asset inventory. The method includes obtaining data related to assets of the asset inventory and analyzing the obtained data to estimate a total number of assets required by the asset inventory over a time period. The method also includes determining a first cost of owning an asset and a second cost of leasing an asset, and allocating the asset inventory between a first number of owned assets and a second number of leased assets to achieve an estimated least-cost value of maintaining the total number of assets over the time period. The method also includes determining a schedule for leasing the second number of assets to be leased for the asset inventory Computer-readable medium that afford functionality of the type defined by this method is also provided by the present technique.
In accordance with another exemplary embodiment, the present technique provides a system for managing an asset inventory. The system includes a database having data related to assets of the asset inventory. The exemplary system also includes a processor that facilitates analysis of data stored in the database, to estimate a total number of assets required by the asset inventory over a time period and to allocate the asset inventory between a first number of owned assets and a second number of leased assets to substantially reduce the costs of maintaining the total number of assets, for instance.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
As discussed in detail below, embodiments of the present technique function to provide a method of managing an asset inventory for a product. Although the present discussion focuses on managing a spare engine inventory for a fleet of aircraft, the present technique is not limited to engines. Rather, the present technique is applicable to any number of suitable fields in which asset management is desired. Referring now to the drawings,
Typically, the replacement engine 14a is provided through a spare pool 16 that includes a plurality of stand-by engines. It should be noted that an airline or a service provider for the airline owns an appropriate number of engines in the spare pool 16 that may be utilized as replacement engines 14a for the aircraft 12, for example. Alternatively and by way example, if the replacement engine 14a is not available via the spare pool 16, then the replacement engine 14a may be leased from a lease pool 18 for a required time period. Typically, lease pools 18 are operated by a third-party.
Once removed from the aircraft 12, the engine 14 is often transported to a maintenance facility 20 for overhauling or repair, as represented by reference numerals 22. Typically, the removed engine 14 is placed in a “parking lot” 26 (i.e., an interim storage facility), as represented by reference numeral 28. When placed in the parking lot 26, the removed engine 14 enters a queue for transportation to the maintenance facility 20 for maintainence. Depending on the availability of space at the maintenance facility 20, the engine 14 enters the facility 20 for maintainence, as represented by reference numeral 30. In certain embodiments, if the parking lot is empty, the removed engine 14 may be directly transported to the maintenance facility 20. Subsequently, the removed engine 14, once appropriately addressed, may be stored in the spare pool 16, as represented by reference numeral 32. Accordingly, the overhauled engine 14 from the spare pool 16 may be employed as the replacement engine 14a for the aircraft 12, as represented by reference numeral 34. As mentioned before, if a spare engine is not available in the spare pool 16, the engine 14 may be leased or purchased from the lease pool 18, as represented by reference numeral 36. Also, if the number of engines in the spare pool 16 falls below a given contractual threshold, it may be necessary to lease or purchase additional engines from the lease pool 18. When a spare engine is available for use as a replacement engine 14a, leased engines from the lease pool 18 may be returned by replacing it with a newly repaired spare engine from the spare pool 16.
As mentioned above, an engine 14 removed from an aircraft 12 is replaced by a spare engine from the spare pool 16 or by a leased engine from the lease pool 18. Thus, an airline or a service provider for the airline manages a spare engine inventory by allocating the inventory between owned and leased engines. Advantageously, the present technique facilitates optimization of the asset inventory between leased and owned engines, for example.
In a presently contemplated configuration, the database 42 contains data related to the engine 14 of the aircraft 12. Generally, such data includes information such as compartment definitions of the engine, repair history of the engine, environment, operating conditions of the engine, engine life, among others. It should be noted that, as used herein, the term “compartment definition” refers to a physical or performance related subsystem of the engine 14, which, when it fails, suggests that the engine 14 needs maintenance or servicing. In addition, the database 42 may include data such as engine utilization, engine lease acquisition cost, engine repair cost, engine maintenance turnaround time, engine transport time, engine depreciation, engine purchase cost, engine storage cost, engine ownership cost and contract terms. In this embodiment, the plurality of data mentioned above may be stored via a memory device that includes a random-access memory (RAM) and a read-only memory (ROM). However, other types of memory such as programmable read-only memory (PROM), erasable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM) may be employed for storing the data.
Typically, the processor 44 preprocesses the data from the database 42 to generate data in a pre-determined format. In certain embodiments, the preprocessing includes extracting the data from the database 42, assigning each data record in the database 42 to a compartment depending upon various factors such as removal cause, failure mode and so forth. The formatted data may be then analyzed to estimate a total number of engines required by the spare engine inventory over a time period based upon the obtained data. It should be noted that the total number of engines required by the spare engine inventory depends upon failure rate distributions of the components of the engine that are estimated by the processor 44 as described below.
The processor 44 facilitates determination of a plurality of compartment failure data that may include compartment failure parameters and compartment time-to-failure coefficients. As used herein, the term “compartment failure parameters” includes variables that affect the time required for a component of the engine 14 to be serviced. Further, it should be noted that, as used herein, the term “compartment time-to-failure coefficients” includes coefficients that are applied to each of the compartment failure parameters. Further, based upon the estimated compartment failure parameters and the compartment time-to-failure coefficients, the processor 44 estimates failure rate distributions for the components of the engine 14.
In certain embodiments, the processor 44 may cooperate with a statistical analyzer to analyze the data and to execute a plurality of statistical procedures to determine a plurality of compartment failure information, such as statistical diagnostics 46 and residual plots 48. Examples of statistical procedures include multi-variate regression and correlation analysis. The statistical diagnostics 46 may include the compartment time-to-failure coefficients for each compartment associated with the engine. Further, the residual plots 48 enable a user of the system 40 to determine how well the regression model fits into the obtained data, for example.
Moreover, the processor 44 cooperates with a simulator that is configured to forecast failure of the components of the engine over the time period based upon the estimated failure rate distributions of the components. The simulator may be a part of the processor 44 or may be isolated from the processor 44. In particular, the simulator utilizes the compartment time-to-failure coefficients and determines a Weibull distribution for each compartment and such distributions may be employed to determine the overall distribution of the engine. In one embodiment, the simulator employs an event driven Monte Carlo simulation. As a result of the simulation the simulator generates several outputs such as a contract output report 50 and a graphical output 52. The contract output report 50 may include a plurality of information such as maintenance event distribution parameters over the time period, maintenance cost distribution over the time period, demand distributions and so forth. Further, the graphical output may include cost distributions, availability, reliability and other financial information. Thus, from the estimated outputs from the processor 44 information pertaining to various parameters of the components of the engine may be made available to a user of the system 40. Further, this information may be used for managing the spare engine inventory as will be described further below with reference to
Referring now to
As described above, the failure distributions for an engine from a fleet of engines are estimated based upon the obtained data related to the engines. Advantageously, the failure distributions may be utilized for determining shop load distributions over a time period as described with reference to
Referring now to
The estimated total number of engines required by the spare engine inventory may be allocated between a first number of owned engines and a second number of leased engines, the allocation being optimized to reduce the expected total costs of maintaining the total number of spare engines over the time period. In this embodiment, a first cost of owning an engine and a second cost of leasing an engine are determined to estimate the cost of maintaining the total number of assets over the time period. As discussed further below, the cost of maintaining the total number of assets may be substantially reduced by balancing the cost of owning the engines against the cost of leasing the engines in accordance with implementations of the present technique. In the illustrated exemplary embodiment, the allocation of inventory between owned and leased engines is done such that the cost of ownership of spare engine is reduced and the instances when the airline or the service provider is unexpectedly required to lease engine from a lease pool is also reduced, as represented by steps 120 and 122. This optimized allocation of the asset inventory between the owned and leased engines is discussed further below.
The allocation of the asset inventory between the owned and leased engines is done based upon the tradeoff between the first number of owned assets and the second number of leased assets to optimize the cost of maintaining the total number of assets. As a result, the allocation of the engines may advantageously improve a LTSA hit-rate and would also minimize spare engines leasing for the airline or the service provider (steps 124 and 126). As illustrated by step 128, the allocation of the spare engine inventory between the first number of owned assets and a second number of leased engines results in achieving LTSA profitability, thereby reducing the cost of maintaining the total number of engines.
The following discussion provides an exemplary process for determining the optimized allocation between leased and purchased spare engines. The cost of maintaining the total number of engines over a time period, say a month m for instance, is represented by the following equation:
Cm=CL+CO (1)
CL=MAX[E(#spares in use at end of month m)−#spares owned]*Lm (2)
CO=MAX[#spares owned−E(#spares in use at end of month m)]*LO (3)
Where
In certain embodiments, a cost-benefit analysis may be performed over a time period to allocate the asset inventory between leased and owned engines. In this embodiment, the estimated cost of maintaining the total number of engines may be tracked over a time period say a year and the mean yearly estimated cost may be analyzed to determine the optimum number of engines to be owned by the inventory for reducing the total cost of maintaining the total number of assets.
As will be appreciated by those of ordinary skill in the art, the foregoing example, demonstrations, and process steps may be implemented by suitable code on a processor-based system, such as a general-purpose or special-purpose computer. It should also be noted that different implementations of the present technique may perform some or all of the steps described herein in different orders or substantially concurrently, that is, in parallel. Furthermore, the functions may be implemented in a variety of programming languages, such as C++ or JAVA. Such code, as will be appreciated by those of ordinary skill in the art, may be stored or adapted for storage on one or more tangible, machine readable media, such as on memory chips, local or remote hard disks, optical disks (that is, CD's or DVD's), or other media, which may be accessed by a processor-based system to execute the stored code. Note that the tangible media may comprise paper or another suitable medium upon which the instructions are printed. For instance, the instructions can be electronically captured via optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
