Corrective maintenance
Corrective maintenance is a maintenance task performed to identify and rectify a fault so that the failed equipment, machine, or system can be restored to an operational condition within the tolerances or limits established for in-service operations. A French official standard defines "corrective maintenance" as maintenance, carried out after failure detection and is aimed at restoring an asset to a condition in which it can perform its intended function. Corrective maintenance can be subdivided into "immediate corrective maintenance" and "deferred corrective maintenance"; the technical standards concerning corrective maintenance are set by IEC 60050 chapter 191 °Dependability and quality of service"The NF EN 13306 X 60-319 is a subset of IEC 60050-191. The decision to choose corrective maintenance as a method of maintenance is a decision depending on several factors as the cost of downtime, reliability characteristics and redundancy of assets; the steps of corrective maintenance are, following failure, diagnosis – elimination of the part, causing the failure – ordering the replacement – replacement of the part – test of function and the continuation of use.
The basic form of corrective maintenance is a step-by-step procedure. The object's failure triggers the steps. Modern technologies as the use of Industry 4.0 features reduce the inherant drawbacks of corrective maintenance. By e.g. providing device history, fault patterns, repair availability of spare parts. Preventive maintenance Predictive maintenance L. C. Morow: Maintenance Engineering Hand Book, Mc Graw Hill, New York, 1952 S. Nakajima: Introduction to TPM, Productivity Press, Massachusetts, 1988 Peter Willmott: Total Production Maintenance the Western Way, Heinemann, First Published 1994, London
Predictive maintenance
Predictive maintenance techniques are designed to help determine the condition of in-service equipment in order to estimate when maintenance should be performed. This approach promises cost savings over routine or time-based preventive maintenance, because tasks are performed only when warranted. Thus, it is regarded as condition-based maintenance carried out as suggested by estimations of the degradation state of an item; the main promise of predictive maintenance is to allow convenient scheduling of corrective maintenance, to prevent unexpected equipment failures. The key is "the right information in the right time". By knowing which equipment needs maintenance, maintenance work can be better planned and what would have been "unplanned stops" are transformed to shorter and fewer "planned stops", thus increasing plant availability. Other potential advantages include increased equipment lifetime, increased plant safety, fewer accidents with negative impact on environment, optimized spare parts handling.
Predictive maintenance differs from preventive maintenance because it relies on the actual condition of equipment, rather than average or expected life statistics, to predict when maintenance will be required. Some of the main components that are necessary for implementing predictive maintenance are data collection and preprocessing, early fault detection, fault detection, time to failure prediction, maintenance scheduling and resource optimization. Predictive maintenance has been considered to be one of the driving forces for improving productivity and one of the ways to achieve "just-in-time" in manufacturing. Since 2001, the Center for Intelligent Maintenance Systems has been working in the development of advance methods and technologies for predictive maintenance; the developed approaches have been validated in over 70 projects conducted with research and industry partners for enabling products and systems to achieve and sustain near-zero breakdown. The vision has been to estimate the current health of a plant equipment and predict the next fault event for improved productivity and asset utilization.
ZDT was first coined by IMS Center and adopted by Fanuc in 2013 Predictive maintenance evaluates the condition of equipment by performing periodic or continuous equipment condition monitoring. The ultimate goal of the approach is to perform maintenance at a scheduled point in time when the maintenance activity is most cost-effective and before the equipment loses performance within a threshold; this results in a reduction in unplanned downtime costs because of failure where for instance costs can be in the hundreds of thousands per day depending on industry. In energy production in addition to loss of revenue and component costs, fines can be levied for non delivery increasing costs further; this is in contrast to time- and/or operation count-based maintenance, where a piece of equipment gets maintained whether it needs it or not. Time-based maintenance is labor intensive, ineffective in identifying problems that develop between scheduled inspections, so is not cost-effective; the fundamental idea is to transform the traditional ‘fail and fix’ maintenance practice to a ‘predict and prevent’ approach The "predictive" component of predictive maintenance stems from the goal of predicting the future trend of the equipment's condition.
This approach uses principles of statistical process control to determine at what point in the future maintenance activities will be appropriate. Most predictive inspections are performed while equipment is in service, thereby minimizing disruption of normal system operations. Adoption of PdM can result in higher system reliability. Reliability-centered maintenance emphasizes the use of predictive maintenance techniques in addition to traditional preventive measures; when properly implemented, RCM provides companies with a tool for achieving lowest asset net present costs for a given level of performance and risk. One goal is to transfer the PdM data to a computerized maintenance management system so that the equipment condition data is sent to the right equipment object in the CMMS system in order to trigger maintenance planning, work order execution, reporting. Unless this is achieved, the PdM solution is of limited value, at least if the PdM solution is implemented on a medium to large size plant with tens of thousands pieces of equipment.
In 2010, the mining company Boliden, as a first, implemented a combined Distributed Control System and PdM solution integrated with the plant CMMS system on an object to object level, transferring equipment data using protocols like Highway Addressable Remote Transducer Protocol, IEC61850 and OLE for process control. To evaluate equipment condition, predictive maintenance utilizes nondestructive testing technologies such as infrared, corona detection, vibration analysis, sound level measurements, oil analysis, other specific online tests. A new approach in this area is to utilize measurements on the actual equipment in combination with measurement of process performance, measured by other devices, to trigger equipment maintenance; this is available in collaborative process automation systems. Site measurements are supported by wireless sensor networks to reduce the wiring cost. Vibration analysis is most productive on high-speed rotating equipment and can be the most expensive component of a PdM program to get up and running.
Vibration analysis, when properly done, allows the user to evaluate the condition of equipment and avoid failures. The latest generation of vibration analyzers comprises m
Aircraft maintenance
Aircraft maintenance is the performance of tasks required to ensure the continuing airworthiness of an aircraft or aircraft part, including overhaul, replacement, defect rectification, the embodiment of modifications, compliance with airworthiness directives and repair. The maintenance of aircraft is regulated, in order to ensure safe and correct functioning during flight. National regulations are coordinated under international standards, maintained by bodies such as the International Civil Aviation Organization; the maintenance tasks and inspections are all regulated and staff must be licensed for the tasks they carry out. The Maintenance, Overhaul Market was US$135.1 Billion in 2015, three quarters of the $180.3 B aircraft production market. Of this, 60% is for civil aviation: air transport 48%, business and general aviation 9%, rotorcraft 3%. Of the $64.3 Billion air transport MRO market, 40% is for engines, 22% for components, 17% for line, 14% for airframe and 7% for modifications. Its is projected to grow at 4.1% per annum till 2025 to $96B.
Airliner MRO should reach $74.3 Billion in 2017: 51% single-aisles, 21% long range twin-aisles, 8% medium range twin-aisles, 7% large aircraft, 6% regional jets as turboprop regional airliners and 1% short range twin-aisles. Over the 2017-2026 decade, the worldwide market should reach over $900 billion, led by 23% in North America, 22% in Western Europe, 19% in Asia Pacific. In 2017, of the $70 billion spent by airlines on maintenance and overhaul, 31% were for engines, 27% for components, 24% for line maintenance, 10% for modifications and 8% for the airframe. In 2018, the commercial aviation industry will need $88 billion for MRO while military aircraft should need $79.6 billion including field maintenance for 46.4%. Airliner MRO should reach $115 billion by 2028, a 4% compound annual growth rate from $77.4 billion in 2018. Major airframers Airbus and Embraer enter the market, growing concerns about their intellectual property sharing, while shared data-supported predictive maintenance can reduce operational disruptions: among other factors, prognostics helped Delta Air Lines reduce maintenance cancellations by 98% from 5,600 in 2010 to 78 in 2017.
Insourced maintenance can be inefficient for small airlines with a fleet below 50-60 aircraft. They have to either outsource it or sell its MRO services to other carriers for better resource utilization. For example, the maintenance on South African Comair's 26 Boeing 737s is outsourced to South African Airways' Technical Department. Another example is Spain’s Air Nostrum operates 45 CRJs and ATR72s and its 300-person maintenance department provides line, base maintenance and limited component repair for other airlines 20% of the time. Airframe heavy maintenance is worth $6 billion in 2019: $2.9 billion for C checks and $3.1 billion for D checks, Aviation Week forecasts a growth to $7.5 billion in 2028 - $3.1 billion C and $4.2 billion D - for $70 billion over 10 years, 10% of the overall market compared to 40% for the engines. The commercial aviation engine MRO market is anticipated by Aviation Week to be $25.9 billion in 2018, a 2.5 billion increase from 2017, led by 21% for the Boeing 737NG' CFM56-7B and the A320's CFM56-5B and IAE V2500 tied for second, followed by the mature widebody engines: the GE90 the Trent 700.
Over the 2017-2026 decade, the largest markets for turbofans will be the B737NG's CFM56-7 with 23%, the V2500-A5 with 21%, the GE90-115B with 13%, the A320's CFM56-5B with 13%, the PW1000G with 7%, the Trent 700 with 6%, the CF6-80C2 with 5%, the CFM LEAP with 5% and the CF34-8 with 4%. Between 2018 and 2022, the largest MRO demand will be for CFM engines with 36%, followed by GE with 24%, Rolls with 13%, IAE with 12% and Pratt with 7%; as an aircraft gets older, a greater percentage of its value is represented by its engines. Over the course of the engine life it is possible to put value back in by repair and overhaul, to sell it for its remaining useful time, or to disassemble it and sell the used parts, to extract its remaining value, its maintenance value includes the value of the time before overhaul. The core value is the value of its data plate and non-life-limited-parts. Engine makers discount their sales, up to 90%, to win the multi-year stream of spares and services, resembling the razor and blades model.
Engines installed on a new aircraft are discounted by at least 40% while spare engine values follow list prices. Accounting for 80% of a shop visit cost, LLP prices escalate to recoup the original discount, until engine availability increase with aircraft teardowns. Between 2001 and 2018 for the Airbus A320 or the Boeing 737-800, their CFM56 value increased from 27-29% to 48-52% of the aircraft value; the 777-200ER's PW4000 and the A330-300's Trent 700 engines rose from a share of 18-25% in 2001 to 29-40% in 2013. For the A320neo and 737 MAX, between 52% and 57% of their value lies in their engines: this could rise to 80-90% after ten years, while new A350 or B787 engines are worth 36-40% of the aircraft. After some time the maintenance reserves exceed the aircraft lease. In 2018, a full set of LLP for a B737-800's CFM56-7B list price is $3.6 million, like for the A320ceo's CFM56-5B for 20-30,000 cycles up from $2.0 million in 2009, while an IAE V2500 is priced at $3.9 million for 20,000 cycles but have a lower overhaul cost.
The LLP parts for and A320neo's PW1127G costs $4 mil
Maintenance (technical)
The technical meaning of maintenance involves functional checks, repairing or replacing of necessary devices, machinery, building infrastructure, supporting utilities in industrial, business and residential installations. Over time, this has come to include multiple wordings that describe various cost-effective practices to keep equipment operational. Together, these functions are referred to as Maintenance and overhaul. MRO is used for Maintenance and operations. Over time, the terminology of maintenance and MRO has begun to become standardized; the United States Department of Defense uses the following definitions: Any activity—such as tests, replacements and repairs—intended to retain or restore a functional unit in or to a specified state in which the unit can perform its required functions. All action taken to restore it to serviceability, it includes inspections, servicing, classification as to serviceability, repair and reclamation. All repair action taken to keep a force in condition to carry out its mission.
The routine recurring work required to keep a facility in such condition that it may be continuously used, at its original or designed capacity and efficiency for its intended purpose. Maintenance is connected to the utilization stage of the product or technical system, in which the concept of maintainability must be included. In this scenario, maintainability is considered as the ability of an item, under stated conditions of use, to be retained in or restored to a state in which it can perform its required functions, using prescribed procedures and resources. In some domains like aircraft maintenance, terms maintenance and overhaul include inspection, rebuilding and the supply of spare parts, raw materials, sealants and consumables for aircraft maintenance at the utilization stage. In international civil aviation maintenance means: The performance of tasks required to ensure the continuing airworthiness of an aircraft, including any one or combination of overhaul, replacement, defect rectification, the embodiment of a modification or a repair.
This definition covers all activities for which aviation regulations require issuance of a maintenance release document. The basic types of maintenance falling under MRO include: Preventive maintenance known as PM Corrective maintenance where equipment is repaired or replaced after wear, malfunction or break down. Predictive maintenance, which uses sensor data to monitor a system continuously evaluates it against historical trends to predict failure before it occurs. ReinforcementArchitectural conservation employs MRO to preserve, restore, or reconstruct historical structures with stone, glass and wood which match the original constituent materials where possible, or with suitable polymer technologies when not. Preventive maintenance is "a routine for periodically inspecting" with the goal of "noticing small problems and fixing them before major ones develop." Ideally, "nothing breaks down."The main goal behind PM is for the equipment to make it from one planned service to the next planned service without any failures caused by fatigue, neglect, or normal wear, which Planned Maintenance and Condition Based Maintenance help to achieve by replacing worn components before they fail.
Maintenance activities include partial or complete overhauls at specified periods, oil changes, minor adjustments, so on. In addition, workers can record equipment deterioration so they know to replace or repair worn parts before they cause system failure; the New York Times gave an example of "machinery, not lubricated on schedule" that functions "until a bearing burns out." Preventive maintenance contracts are a fixed cost, whereas improper maintenance introduces a variable cost: replacement of major equipment. Preventive maintenance or preventative maintenance has the following meanings: The care and servicing by personnel for the purpose of maintaining equipment in satisfactory operating condition by providing for systematic inspection and correction of incipient failures either before they occur or before they develop into major defects; the work carried out on equipment in order to avoid its malfunction. It is a routine action taken on equipment in order to prevent its breakdown. Maintenance, including tests, adjustments, parts replacement, cleaning, performed to prevent faults from occurring.
Other terms and abbreviations related to PM are: scheduled maintenance planned maintenance, which may include scheduled downtime for equipment replacement planned preventive maintenance is another name for PM breakdown maintenance: fixing things only when they break. This is known as "a reactive maintenance strategy" and may involve "consequential damage." Planned preventive maintenance, more referred to as planned maintenance or scheduled maintenance, is any variety of scheduled maintenance to an object or item of equipment. Planned maintenance is a scheduled service visit carried out by a competent and suitable agent, to ensure that an item of equipment is operating and to therefore avoid any unscheduled breakdown and downtime; the key factor as to when and why this work is being done is timing, involves a service, resource or facility being unavailable. By contrast, co
Service (motor vehicle)
A motor vehicle service or tune-up is a series of maintenance procedures carried out at a set time interval or after the vehicle has travelled a certain distance. The service intervals are specified by the vehicle manufacturer in a service schedule and some modern cars display the due date for the next service electronically on the instrument panel. A tune-up should not be confused with engine tuning, the modifying of an engine to perform better than the original specification, rather than using maintenance to keep the engine running as it should; the completed services are recorded in a service book, rubber-stamped by the service centre upon completion of each service. A complete service history adds to the resale value of a vehicle; the actual schedule of car maintenance varies depending on the year and model of a car, its driving conditions and driver behaviour. Car makers recommend the so-called extreme or the ideal service schedule based on impact parameters such as number of trips and distance travelled per trip per day extreme hot or cold climate conditions mountainous, dusty or de-iced roads heavy stop-and-go vs. long-distance cruising towing a trailer or other heavy loadExperienced service advisors in dealerships and independent shops recommend schedule intervals, which are in between the ideal or extreme service schedule.
They base it on behaviour of the car owner or driver. Maintenance tasks carried out during a motor vehicle service include: Change the engine oil Replace the oil filter Replace the air filter Replace the fuel filter Replace the cabin filter Replace the spark plugs Check level and refill brake fluid/clutch fluid Check Brake Pads/Liners, Brake Discs/Drums, replace if worn out. Check level and refill power steering fluid Check level and refill Automatic/Manual Transmission Fluid Grease and lubricate components Inspect and replace the timing belt or timing chain if needed Check condition of the tires Check for proper operation of all lights, wipers etc. Check for any Error codes in the ECU and take corrective action. Use scan tool read trouble code. Mechanical parts that may cause the car to cease transmission or prove unsafe for the road are noted and advised upon. In the United Kingdom, few parts that are not inspected on the MOT test are inspected and advised upon a Service Inspection, including Clutch, Car Battery, Engine components.
Auto mechanic Automobile repair shop Car ramp, a means of accessing the underside of a vehicle Engine tuning Italian tuneup Mechanical engineering Exhaust gas analyzer
