HOME

TheInfoList




A spare part, spare, service part, repair part, or replacement part, is an
interchangeable part Interchangeable parts are parts (wikt:component#Noun, components) that are, for practical purposes, identical. They are made to specifications that ensure that they are so nearly identical that they will fit into any assembly of the same type. One s ...
that is kept in an inventory and used for the repair or replacement of failed units. Spare parts are an important feature of logistics engineering and
supply chain management File:Supply and demand-stacked4.png , 400px, In an efficient supply chain agreements are aligned In commerce, supply chain management (SCM), the management of the flow of good (economics), goods and Service (economics), services, between busi ...
, often comprising dedicated spare parts management systems. Capital spares are spare parts which, although acknowledged to have a long life or a small chance of
failure Failure is the state or condition of not meeting a desirable or intended , and may be viewed as the opposite of . The criteria for failure depends on context, and may be relative to a particular observer or belief system. One person might con ...

failure
, would cause a long shutdown of equipment because it would take a long time to get a replacement for them. Spare parts are an outgrowth of the industrial development of interchangeable parts and
mass production Mass production, also known as flow production or continuous production, is the production of substantial amounts of standardized Standardization or standardisation is the process of implementing and developing technical standard A technic ...
.


Classification

In
logistics Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics is the management of the flow of things between the point of origin and the point of consumption to meet the requ ...

logistics
, spare parts can be broadly classified into two groups,
repairable A repairable component is a component of a finished good that can be designated for repair. Repairable components tend to be more expensive than non-repairable components (consumables). This is because for items that are inexpensive to procuremen ...
s and
consumable Consumables (also known as consumable goods, non-durable goods, or soft goods) are goods that are intended to be wikt:consume, consumed. People have, for example, always consumed food and water. Consumables are in contrast to durable goods. Dispos ...
s. Economically, there is a tradeoff between the cost of
ordering Order or ORDER or Orders may refer to: * Orderliness, a desire for organization * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements hav ...
a replacement part and the cost of repairing a failed part. When the cost of repair becomes a significant percentage of the cost of replacement, it becomes economically favorable to simply order a replacement part. In such cases, the part is said to be "beyond economic repair" (BER), and the percentage associated with this threshold is known as the BER rate. Analysis of economic tradeoffs is formally evaluated using
Level of Repair Analysis Level of Repair Analysis (LORA) is used as an analytical methodology used to determine where an item will be replaced, repaired, or discarded based on cost considerations and availability, operational readiness requirements. For a complex engineer ...
(LORA).


Repairable

Repairable parts are parts that are deemed worthy of repair, usually by virtue of economic consideration of their repair cost. Rather than bear the cost of completely replacing a finished product, repairables typically are designed to enable more affordable maintenance by being more modular. That allows components to be more easily removed, repaired, and replaced, enabling cheaper replacement. Spare parts that are needed to support condemnation of repairable parts are known as ''replenishment'' spares . A rotable pool is a pool of repairable spare parts inventory set aside to allow for multiple repairs to be accomplished simultaneously, which can be used to minimize
stockout A stockout, or out-of-stock (OOS) event is an event that causes inventory Inventory (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the ...
conditions for repairable items.


Consumable

Parts that are not repairable are considered consumable parts. Consumable parts are usually
scrap Scrap consists of recyclable Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depe ...

scrap
ped, or "condemned", when they are found to have failed. Since no attempt at repair is made, for a fixed
mean time between failures Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system, during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a syste ...
(MTBF), replacement rates for consumption of consumables are higher than an equivalent item treated as a repairable part. Therefore, consumables tend to be lower-cost items. Because consumables are lower cost and higher volume,
economies of scale 330px, As quantity of production increases from Q to Q2, the average cost of each unit decreases from C to C1. LRAC is the long-run average cost In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their sca ...

economies of scale
can be found by ordering in large lot sizes, a so-called
economic order quantityEconomic Order Quantity (EOQ), also known as Economic Purchase Quantity (EPQ), is the order quantity that minimizes the total holding cost In marketing, carrying cost, carrying cost of inventory or holding cost refers to the total cost of holding inv ...
.


Legislation

There is no UK or
EU
EU
legislation Legislation is the process or product of enrolling, enacting, or promulgating Promulgation is the formal proclamation or the declaration that a new statute, statutory or administrative law is enacted after its final Enactment of a bill, appro ...
which states that spare parts have to be available for any set period of time, but some
trade association A trade association, also known as an industry trade group, business association, sector association or industry body, is an organization founded and funded by businesses that operate in a specific . An industry trade association participates in ...
s require their members to ensure products are not rendered useless because spare parts are not available. The 'six year rule' in the UK
Sale of Goods Act 1979 The Sale of Goods Act 1979c 54 is an Act of Parliament, Act of the Parliament of the United Kingdom which regulated English contract law and UK commercial law in respect of goods that are sold and bought. The Act consolidated the original Sale o ...
relates to the time period for enforcing claims that goods where defective when sold, not to whether spare parts are available to repair them, and section 23(3) of the
Consumer Rights Act 2015 The Consumer Rights Act 2015 is an Act of Parliament of the United Kingdom The Parliament of the United Kingdom is the Parliamentary sovereignty in the United Kingdom, supreme Legislature, legislative body of the United Kingdom, the Crow ...
states that a
consumer A consumer is a person or a group who intends to order, orders, or uses purchased goods, products, or Service (economics), services primarily for personal, social, family, household and similar needs, not directly related to entrepreneurial or bu ...
cannot require a trader to repair or replace goods if "the repair or replacement is impossible", implying that if spare parts are no longer available the consumer's Right to Repair (or to have a spare part supplied) would be lost.Consumer Rights Act 2015
section 23(3)


Repair cycle

From the perspective of
logistics Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics is the management of the flow of things between the point of origin and the point of consumption to meet the requ ...

logistics
, a model of the life cycle of parts in a
supply chain In commerce, a supply chain is a system of organizations, people, activities, information, and resources involved in supplying a product (business), product or service (business), service to a consumer. Supply chain activities involve the transfo ...

supply chain
can be developed. This model, called the repair cycle, consists of functioning parts in use by equipment operators, and the entire sequence of
suppliers In commerce, a supply chain is a system of organizations, people, activities, information, and resources involved in supplying a product (business), product or service (business), service to a consumer. Supply chain activities involve the transfor ...
or repair providers that replenish functional part inventories, either by production or repair, when they have failed. Ultimately, this sequence ends with the
manufacturer Manufacturing is the creation or production Production may be: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in the outline of industrial organization, the act of making products (g ...
. This type of model allows demands on a supply system to ultimately be traced to their operational
reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), Data reliability, a property of some disk arrays in computer storage * High availability * Reliability (computer ...
, allowing for analysis of the dynamics of the supply system, in particular, spare parts.


Inventory management


Cannibalization

When
stockout A stockout, or out-of-stock (OOS) event is an event that causes inventory Inventory (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the ...
conditions occur, cannibalization can result. This is the practice of removing parts or subsystems necessary for repair from another similar device, rather than from
inventory Inventory () or stock () refers to the goods and materials that a holds for the ultimate goal of resale, production or utilisation. is a discipline primarily about specifying the shape and placement of stocked goods. It is required at differen ...
. The source system is usually crippled as a result, if only temporarily, in order to allow the recipient device to function properly again. As a result, operational availability is impaired.


Commercial

Industrialization Factories, refineries, mines, and agribusiness are all elements of industrialisation Industrialisation ( alternatively spelled industrialization) is the period of social and economic change that transforms a human group from an agrarian societ ...
has seen the widespread growth of commercial
manufacturing Manufacturing is the creation or Production (economics), production of goods with the help of equipment, Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector ...
enterprises, such as the
automotive industry The automotive industry comprises a wide range of and s involved in the , , , , and of s. It is one of the world's largest by . The automotive industry does not include industries dedicated to the of following delivery to the end-user, such ...
, and later, the
computer industry A computer is a machine A machine is any physical system with ordered structural and functional properties. It may represent human-made or naturally occurring device molecular machine that uses Power (physics), power to apply Force, for ...
. The resulting complex systems have evolved modular support infrastructures, with the reliance on
auto parts This is a list of auto parts, mostly for vehicles using internal combustion engines which are manufacturing, manufactured components of automobiles: Car body and main parts Body components, including trim Vehicle door, Doors Windows Lo ...
in the automotive industry, and replaceable computer modules known as
field-replaceable unitA field-replaceable unit (FRU) is a printed circuit board, part, or assembly that can be quickly and easily removed from a computer or other piece of electronic equipment, and replaced by the user or a technician without having to send the entire pro ...
s (FRUs).


Military

Military operations are significantly affected by
logistics Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics is the management of the flow of things between the point of origin and the point of consumption to meet the requ ...

logistics
operations. The system availability, also known as mission capable rate, of
weapon system#REDIRECT Weapon System Legend for Numeric Designations CL: Lockheed D: Douglas NA: North American WS (Weapon System) Weapon System was a United States Armed Forces The United States Armed Forces are the Military, military forces of the U ...
s and the ability to effect the repair of damaged equipment are significant contributors to the success of military operations. Systems that are in a mission-incapable (MICAP) status due lack of spare parts are said to be "awaiting parts" (AWP), also known as not mission capable due to supply (NMCS). Because of this sensitivity to logistics, militaries have sought to make their
logistics Logistics is generally the detailed organization and implementation of a complex operation. In a general business sense, logistics is the management of the flow of things between the point of origin and the point of consumption to meet the requ ...
operations as effective as possible, focusing effort on operations research and optimal maintenance. Maintenance has been simplified by the introduction of interchangeable
modules Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a syst ...

modules
known as
line-replaceable unit A line-replaceable unit (LRU), lower line-replaceable unit (LLRU), line-replaceable component (LRC), or line-replaceable item (LRI) is a modular component of an airplane An airplane or aeroplane (informally plane) is a fixed-wing aircraft ...
s (LRUs). LRUs make it possible to quickly replace an unserviceable (failed) part with a serviceable (working) replacement. This makes it relatively straightforward to repair complex military hardware, at the expense of having a ready supply of spare parts. The cost of having serviceable parts available in inventory can be tremendous, as items that are prone to failure may be demanded frequently from inventory, requiring significant inventory levels to avoid depletion. For military programs, the cost of spare inventory can be a significant portion of acquisition cost. In recent years, the
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government A federation (also known as a federal state) is a political entity A polity is an identifiable political entityâ ...
(DoD) has advocated the use of
performance-based logisticsPerformance-based logistics (PBL), also known as performance-based life-cycle product support or performance-based contracting, is a strategy for cost-effective weapon system#REDIRECT Weapon System Legend for Numeric Designations CL: Lockheed D: ...
(PBL) contracts to manage costs for support of weapon systems.


See also

*
Buffer stock scheme A buffer stock scheme (commonly implemented as intervention storage, the "ever-normal granary") is an attempt to use commodity storage for the purposes of price stability, stabilising prices in an entire economy or an individual (commodity) mark ...

Buffer stock scheme
*
Carrier onboard delivery Carrier onboard delivery (COD) is the use of aircraft to ferry personnel, mail, supplies, and high-priority cargo, such as replacement parts, from shore bases to an aircraft carrier An aircraft carrier is a that serves as a seagoing , equ ...
*
Complete knock down A knock-down kit (also knockdown kit, knocked-down kit, or simply knockdown or KD) is a collection of parts required to assemble a product. The parts are typically manufactured in one country or region, then export An export in internatio ...
*
Demand chain The demand chain is that part of the value chain which drives demand.Madhani, P. M. (2013). Demand Chain Management: Enhancing Customer Value Proposition. ''The European Business Review'', March – April, pp. 50–54. Concept Analysing the firm ...
* Flight spare *
Logistics support analysis Integrated logistic support (ILS) is a technology in the system engineering to lower a product life cycle cost and decrease demand for logistics Logistics is generally the detailed organization and implementation of a complex operation. In a g ...
*
Military surplus Military surplus are goods, usually matériel, that are sold or otherwise disposed of when no longer needed by the military. Entrepreneurs often buy these goods and resell them at surplus stores. Usually the goods sold by the military are clo ...

Military surplus
*
Overstock Overstock, excessive stock, excess2sell, B-stock, or excess inventory, is the result of poor management of stock demand or of material flow in process management. Excessive stock is also associated with loss of revenue owing to additional Financial ...
* Reorder point *
Safety stockSafety stock is a term used by logisticians to describe a level of extra stock that is maintained to mitigate risk of stockouts (shortfall in raw material or packaging) caused by uncertainties in supply and demand. Adequate safety stock levels permi ...
*
Service life A product's service life is its period of use in service. It is mostly used in a non-technical context and has no scientific support or meaning. Several other terms more accurately describe a product's life, from the point of manufacture, storage ...
(lifespan) *
Spare tire A spare tire (or stepney) is an additional tire (or tyre - see spelling differences) carried in a motor vehicle as a replacement for one that goes Flat tire, flat, has a Blowout (tire), blowout, or has another emergency. ''Spare tire'' is gene ...
*
Underway replenishment Replenishment at sea (RAS) (North Atlantic Treaty Organisation The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental mili ...
*
Warranty In contract A contract is a legally binding agreement that defines and governs the rights and duties between or among its parties Image:'Hip, Hip, Hurrah! Artist Festival at Skagen', by Peder Severin Krøyer (1888) Demisted with DXO Phot ...
*
War Reserve Stock A war reserve stock (WRS), also known as pre-positioned stocks, is a collection of warfighting material held in reserve in pre-positioned storage to be used if needed in wartime. They may be located strategically depending on where it is believed ...


References

{{Authority control Systems engineering Costs Inventory