Maintenance, repair, and overhaul

Maintenance management effort, 25 461t Maintenance paints, 7 182-184 Maintenance repair and overhaul (MRO), 25 470-471... 

Supply Chain Management in Maintenance Repair, and Overhaul Operations... 

Supply chain management in production operations for new products tends to be rather binary information flows backward from the customer and products flow forward from the digging it out of the ground suppliers, through various tiers of transformation until it arrives to satisly the customer need. Maintenance, repair, and overhaul (MRO) operations are different. This case study covers the supply chain issues of a multinational... 

Maintenance, Repair and Overhaul (MRO) A class of activity occurring after the sale of the product. MRO often demands special supply chain design and can be an important factor in the success of a product that has a long life cycle. 

Back in the 1980s, military avionics systems used a federated architecture, whereby each application or function was implemented using a dedicated processor, as shown in Figure 1. This approach provides intrinsically robust separation of applications and fault isolation, but it has a number of drawbacks. It is expensive in terms of Maintenance, Repair and Overhaul (MRO), as spares for each of the Line Replaceable Units (LRUs) need to be located at each of the maintenance sites, and training is required to install, diagnose and fix each type of LRU. The federated architecture also has significant drawbacks in terms of size, weight and power (SWaP) and obsolescence. 

The SCOR systematic places return processes both upstream and downstream of the supply chain. The source return processes refer to the return of raw material or components to suppliers, whereas the deliver return processes address the receipt of returned finished goods from customers. Furthermore there is the return of empty containers. For all situations, three different return processes are defined (for defective products, MRO (maintenance, repair, and overhaul) products, and excess products). They are not mutually exclusive and can (or even should) be exercised simultaneously, depending on the chosen supply chain strategy and other factors such as product complexity and service level offered to the customer. 

A few aeronautical engineers are also employed in civil aviation by airlines and airfreight operators, or in the growing market for maintenance, repair and overhaul of mihtary and commercial aircraft. However, a more common route for engineers in the civil operating companies is to start as aircraft technicians and to develop to engineer status. There can also be opporturrities to spend periods of time seconded... 

Maintenance is not a glamorous procedure however, its importance is second to none. Maintenance procedures are always controversial, since the definition of upkeep varies with the individual interpretation of each maintenance supervisor. The latitude of maintenance ranges from strict planning and execution, inspection and overhaul, accompanied by complete reports and accounting of costs, to the operation of machinery until some failure occurs, and then making the necessary repairs. 

Within a typical world-class industrial commodity chemical company the annual cost of maintenance is 3 to 6 percent of the asset replacement costs. A number of significant maintenance activities require very little interruption of continuously operating chemical plants. Everyday maintenance activities that may be accomplished on a routine basis include repairs to a spare pump or spare compressor after it has been properly isolated and cleared of fluids, and overhaul of a fully spared filter or painting. 

The process of operation of the supply chain is as follows. When aircrafts generate demand for replacements, also called service parts. These service parts are supplied from the local inventory at air stations. This inventory is replenished by the central warehouse facility at Elizabeth City. In 2001, the total number of individual parts managed at the central facility exceeded 60,000 parts, and the total value of the inventory exceeded 70 million. When working parts are shipped from the warehouse to the air station to satisfy aircraft demand, the salvageable broken components, from all air stations, are shipped back to the warehouse for repair and reuse. The aircraft from all air stations also come for periodic overhaul (depot maintenance) to the Elizabeth City facility, and thus generate demand for parts. Of the total parts in the system, about 6,000 are repaired both internally and by outside commercial vendors. The total annual budget for parts purchases, parts repair, and depot-level maintenance exceeds 140 million. 

Preventive maintenance activities include equipment checks, scheduled or craidition-based worn tool changes, cleaning, and partial or complete overhauls at specified periods, e.g., oil changes and lubrication. In addition, workers can record equipment deterioration so they know to replace or repair worn parts before they cause system failure. In the case of condition-based maintenance, sensors and software tools are used for the monitoring and analysis of the desired item parameters. 

It needs about 20 days of complete stoppage for annual overhaul and maintenance. It is also estimated that the plant would be stopped for a total of about 15 days due to various reasons during the year such as sulphur spray gun choking, air blower maintenance, repair to control valves in acid lines, etc. 

Reliability and maintainability analysis, based on breakdown, repair, and periodic maintenance statistics obtained for each plant item (or even on sensible guesses from experienced people). In conjunction with economic data, the model is used to predict plant availability and economic performance while taking into account the probability of failure of individual components and the repair time. The model may be used to make optimum choices on the provision of standby equipment, equipment enhancement, operational flexibility enhancement (including optimizing the period between overhauls), maintenance facilities, intermediate tankage or stockpile capacity, and capacity margins for individual equipment items. 

During the first nine months of 1943 the loth Chemical Maintenance Company at Brisbane, commanded by Capt. John J. Shaffer, conducted extensive flame thrower tests in order to locate the major sources of trouble, a project which included the thorough overhaul of all flame throwers in the Southwest Pacific Area. The unit discovered that most malfunctions resulted from deteriorated cylinders and batteries which had succumbed to the deleterious temperatures and humidity of the tropics. All flame throwers shipped to the Southwest Pacific or carried as equipment by units arriving in the area were thoroughly tested, repaired, and waterproofed by trained technicians under the direction of Colonel Copthorne and his staff. Though fundamental defects remained, the work of the SWPA Chemical Section went a long way in effectively preventing a repetition of the mishaps suffered on Buna. 

The guide emphasizes the need to set up an effective system of maintenance for PPE. This should be proportionate to the risks and appropriate to the particular PPE. It could include, where appropriate, cleaning, disinfection, examination, replacement, repair and testing. For example, mechanical fall arrestor equipment or sub-aqua breathing apparatus will require planned preventative maintenance with examination, testing and overhaul. Records should be kept of the maintenance work. Gloves may only require periodic inspection by the user as necessary, depending on their use. 

Modern types of low-maintenance and valve-regulated traction batteries fullfil the requirements so battery charging can be performed safely and under optimal economic conditions. In any case for overhaul, repairs, and maintenance there should be a workshop for internal or external educated personnel the single charge point is not the right place for this. 

Apart from daily routines, periodic boiler housekeeping, equipment lubrication, inspection, testing, maintenance, and cleaning, overhaul and repair work becomes necessary. 

During the manufacture of a new aircraft, FAR Part 121.707 -Alteration and repair reports requires die airframe manufacturer to keep a copy of each report of a major repair available for inspection. Airplane operators therefore require a record of major pre-delivery repairs. For economic and logistical reasons they have a need to know about any pre-delivery repairs that will affect their maintenance operations. In response to these customer requirements, original equipment manufacturers (OEMs) compile a Significant Rework Log for each airplane and deliver it with the airplane. Rework/repair is deemed significant when it may have an impact on the way the airplane operator will perform repair, maintenance, or overhaul, or affect the inspection program that the airplane operator must follow. 

Unintermpted supply of raw materials, additives, catalysts, etc., is required for production, while spare parts are required for timely maintenance. This in turn depends on the stock of usable raw materials and spares available in stores (to quickly repair the machinery whenever required). Spares are also required during annual plant shutdown or during overhauling period for replacements of worn out or damaged components. 

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