The document outlines the principles and practices of maintenance engineering, focusing on the importance of planned maintenance activities to achieve machine reliability and availability. It emphasizes the need for effective maintenance planning, preventative maintenance strategies, and the benefits of sound maintenance systems, such as cost reduction and improved equipment lifespan. Additionally, it discusses the role of maintenance organizations in achieving optimal operational conditions and the evaluation of their effectiveness in minimizing production disruptions.

1. Aircraft Condition
Monitoring
UNIT-I
Prepared by Jhumki Nandy
Department of Aeronautical Engineering, Sanjay Ghodawat University Kolhapur

2. ROAD MAP
1. Basic Principles of maintenance planning
2. Objectives and principles of planned maintenance activity
3. Importance and benefits of sound Maintenance systems
4. Reliability and machine availability, MTBF,MTTR and MWT
5. Factors of availability
6. Maintenance organization, Maintenance economics. Maintenance categories
7. Comparative merits of each category
8. Preventive maintenance, maintenance schedules, repair cycle
9. Principles and methods of lubrication, TPM.

3. Maintenance engineering : Maintenance engineering is
the activity of applying engineering concepts to the
optimization of equipment, procedure and departmental budgets
to achieve better maintainability, reliability and
availability of equipment.
Planning: Planning ensures the smooth operation of the system.
Planning defines what is to be done and how it is to be done. It
specifies the materials, tool, equipment and skills required to
perform the work.

4. Main classification of planning in engineering system are as follows,
1. Long range planning
2. Short range planning
3. Planning for immediate activity
1.Long Range planning : For a period of five years at least. Involves capital
budgeting, strategies and operational programmers.
2. Short range: up to one year. Made to achieve short term goals.
3. Immediate Activity Planning : it is done frequently whenever required

5. Objectives of Planned Maintenance Activity
 To achieve minimum breakdown and to keep the plant in good working condition at the lowest
possible cost.
 To ensure the availability of machines and services in an optimum working condition.
 To keep machines and other facilities in a condition to be used to achieve the maximum profit
without
any interruption.
 To keep the time schedule of delivery to customers.
 To meet the availability requirements for critical equipment.
 To keep the maintenance costs as low as possible for non-critical equipment.
 To control the effective and trained supervision.
 To meet the quality requirements of the product.
 To increase the profits of production systems.

6. Principles of Maintenance :They are followed in a system to guide the staff to work efficiently and effectively
to achieve the overall objectives of the maintenance system,
Main areas of work governed by this principles are
Plant management in Maintenance work
Production and maintenance objectives
Establishment of work order and recording system
Information based Decision making
Adherence to planned maintenance strategy .
Manpower for Maintenance
Planning for maintenance functions
Role of Spare parts
Training.

7. SOUND MAINTENANCE SYSTEM
The following are the benefits of sound maintenance management system
 Minimization of down time
 Improvement in availability of system
 Extended life of equipment
 Safety and smooth operation of the process
 Providing adequate back up supply
 Minimization of normal expected wear and tear of equipment
 Safety of the personal involved in the organization
 Increasing the reliability of the system
 Providing a proper working environment
 Cost effective maintenance boosts the profit of the production system.

8. Reliability: Reliability is the probability that a component/system when operating under given condition
will perform its intended functions adequately for a specified period of time.

9. Equipment lifecycle: Reliability engineering is dependability in the life cycle management of product. The failure
pattern of equipment over its life cycle can be represented as bath-tub curve.

10. Mean Time To Failure(MTTF):Mean Time To Failure (MTTF) is a very basic measure of reliability used for non-
repairable systems. It represents the length of time that an item is expected to last in operation until it fails.

11. Mean Time Between Failures(MTBF): The term MTBF is used for repairable systems, but it does not take into
account units that are shut down for routine scheduled maintenance

12. Mean Time To Repair (MTTR):It refers to the amount of time required to repair a system and restore it to full
functionality. The MTTR clock starts ticking when the repairs start and it goes on until operations are restored. This
includes repair time, testing period, and return to the normal operating condition.

13. Planned
maintenance
work waiting to
be scheduled

15. LIFE CYCLE COST ANALYSIS
D
Initial
Cost
Disposal
Cost
Operating
Cost
Preventive
Maintenance
Cost
Service
Cost
LIFE CYCLE COST
ANALYSIS

17. ROLE OF MAINTENANCE ORGANIZATION
 Too many maintenance functions continue to pride themselves on how fast they can react to a catastrophic failure
or production interruption rather than on their ability to prevent these interruptions.
 Although few production engineers will admit their continued adherence to this breakdown mentality, most
plants continue to operate in this mode.
MAINTENANCE MISSION
Contrary to popular opinion, the role of maintenance is not to “fix” breakdown in record time; rather, it is
to prevent all losses that are caused by equipment or system related problems. The mission of the
maintenance department in a world-class organization is to achieve and sustain the following:
• Optimum availability
• Optimum operating conditions
• Maximum utilization of maintenance resources
• Optimum equipment life
• Minimum spares inventory
• Ability to react quickly

18. Optimum Availability
 The production capacity of a plant is partly determined by the availability of production systems
and their auxiliary equipment.
 The primary function of the maintenance organization is to ensure that all machinery, equipment,
and systems within the plant are always online and in good operating condition.
Optimum Operating Condition
 Availability of critical process machinery is not enough to ensure acceptable plant performance
levels.
 The maintenance organization must maintain all direct and indirect manufacturing machinery,
equipment, and systems so that they will continuously be in optimum operating condition.
 Minor problems, no matter how slight, can result in poor product quality, reduced production
speeds, or other factors that limit overall plant performance.

19. Maximum Utilization of Maintenance Resources
 The maintenance organization controls a substantial part of the total operating budget in most plants.
 In addition to an appreciable percentage of the total-plant labor budget, the maintenance manager often
controls the spare parts inventory, authorizes the use of outside contract labor, and requisitions millions of
dollars in repair parts or replacement equipment.
 Therefore, one goal of the maintenance organization should be effective use of these resources.
Optimum Equipment Life
 One way to reduce maintenance cost is to extend the useful life of plant equipment.
 The maintenance organization should implement programs that will increase the useful life of all plant
assets.

20. Minimum Spares Inventory
 Reductions in spares inventory should be a major objective of the maintenance organization; however, the
reduction cannot impair their ability to meet the first four goals.
 With the predictive maintenance technologies that are available today, maintenance can anticipate the
need for specific equipment or parts far enough in advance to purchase them on an as-needed basis.
Ability to React Quickly
All catastrophic failures cannot be avoided; therefore, the maintenance organization must be able to react
quickly to the unexpected failure.

21. EVALUATION OF THE MAINTENANCE ORGANIZATION
 One means to quantify the maintenance philosophy in your plant is to analyze the maintenance
tasks that have occurred over the past two to three years.
 Attention should be given to the indices that define management philosophy.
 One of the best indices of management attitude and the effectiveness of the maintenance
function is the number of production interruptions caused by maintenance related problems.
 If production delays represent more than 30 percent of total production hours, reactive or
breakdown response is the dominant management philosophy.
 To be competitive in today’s market, delays caused by maintenance-related problems should
represent less than 1 percent of the total production hours.

22. EVALUATION OF THE MAINTENANCE ORGANIZATION(Contd.)
 Another indicator of management effectiveness is the amount of maintenance overtime
required to maintain the plant.
 In a breakdown maintenance environment, overtime costs are a major, negative cost.
 If your maintenance department’s overtime represents more than 10 percent of the total labor
budget, you definitely qualify as a breakdown operation.
 Some overtime is, and always will be, required. Special projects and the 1 percent of delays
caused by machine failures will force some expenditure of overtime premiums, but these
abnormal costs should be a small percentage of the total labor costs.

23. EVALUATION OF THE MAINTENANCE ORGANIZATION(Contd.)
 Labor usage is another key to management effectiveness.
 Evaluate the percentage of maintenance labor, compared to total
available labor hours that are expended on the actual repairs and
maintenance prevention tasks.
 In reactive maintenance management, the percentage will be less than
50 percent.
 A well-managed maintenance organization should maintain consistent
labor usage above 90 percent.
 In other words, at least 90 percent of the available maintenance labor
hours should be effectively used to improve the reliability of critical plant
systems, not spent waiting for something to break.

34. Preventive Maintenance
 As the name implies, preventive maintenance tasks are intended to prevent unscheduled
downtime and premature equipment damage that would result in corrective or repair
activities.
 This maintenance management approach is predominantly a time driven schedule or
recurring tasks, such as lubrication and adjustments that are designed to maintain
acceptable levels of reliability and availability.

35. Preventive Maintenance (Advantages& Disadvantages):
There are distinct advantages to preventive maintenance management. The predominant advantages
include the following:
• Management control. Unlike repair maintenance, which must react to failures, preventive maintenance
can be planned. This means “pre-active” instead of “reactive” management. Workloads may be scheduled
so that equipment is available for preventive activities at reasonable times.
• Overtime. Overtime can be reduced or eliminated. Surprises are reduced. Work can be performed when
convenient; however, proper distribution of the time-driven preventive maintenance tasks is required to
ensure that all work is completed in a timely manner without excessive overtime.
• Parts inventories. Because the preventive maintenance approach permits planning of which parts are going
to be required and when, those material requirements may be anticipated to be sure they are on hand for
the event. A smaller stock of parts is required in organizations that emphasize preventive tasks compared to
the stocks necessary to cover breakdowns that would occur when preventive maintenance is not
emphasized.

36. Preventive Maintenance (Advantages& Disadvantages)(Contd.):
• Standby equipment. With high demand for production and low equipment availability, reserve, standby equipment is
often required in case of breakdowns. Some backup may still be required with preventive maintenance, but the need
and investment will certainly be reduced.
• Safety and pollution. If no preventive inspections or built-in detection devices are used, equipment can deteriorate to a
point where it is unsafe or may spew forth pollutants. Performance will generally follow a saw-tooth pattern, as shown in
Figure 3–2, which does well after maintenance and then degrades until the failure is noticed and it is brought back up to a
high level. A good detection system catches degrading performance before it reaches too low a level.
• Quality. For the same general reasons discussed previously, good preventive maintenance helps ensure quality output.
Tolerances are maintained within control limits. Naturally, productivity is improved and the investment in preventive
maintenance pays off with increased revenues.

37. Preventive Maintenance (Advantages& Disadvantages)(Contd.):
• Support to users. If properly publicized, preventive tasks help show equipment operators, production
managers, and other equipment users that the maintenance function is striving to provide a high level of
support. Note here that an effective program must be published so that everyone involved understands
the value of performed tasks, the investment required, and their own roles in the system.
• Cost–benefit relationship. Too often, organizations consider only costs without recognizing the benefit
and profits that are the real goal. Preventive maintenance allows a three-way balance between corrective
maintenance, preventive maintenance, and production revenues.

38. Disadvantages.
Despite all the good reasons for doing preventive maintenance, several potential problems must be
recognized and minimized:
• Potential damage. Every time a person touches a piece of equipment, damage can occur through neglect, ignorance,
abuse, or incorrect procedures. Unfortunately, low-reliability people often service much high reliability equipment. The
Challenger space shuttle failure, the Three Mile Island nuclear power plant disaster, and many less-publicized accidents
have been affected by inept preventive maintenance. Most of us have experienced car or home appliance problems that
were caused by something that was done or not done at a previous service call. This situation gives rise to the slogan: “If
it works, don’t fix it.”
• Infant mortality. New parts and consumables have a higher probability of being defective or failing than exists with the
materials that are already in use. Replacement parts are too often not subjected to the same quality assurance and
reliability tests as parts that are put into new equipment.

39. Disadvantages.
• Parts use. Replacing parts at pre planned preventive maintenance intervals, rather than waiting until a
failure occurs, will obviously terminate that part’s useful life before failure and therefore require more
parts. This is part of the trade-off among parts, labor, and downtime, of which the cost of parts will usually
be the smallest component. It must, however, be controlled.
• Initial costs. Given the time-value of money and inflation that causes a dollar spent today to be worth
more than a dollar spent or received tomorrow, it should be recognized that the investment in preventive
maintenance is made earlier than when those costs would be incurred if equipment were run until failure.
Even though the cost will be incurred earlier—and may even be larger than corrective maintenance costs
would be—the benefits in terms of equipment availability should be substantially greater from doing
preventive tasks.

40. Disadvantages.
• Access to equipment. One of the major challenges when production is at a high rate is for maintenance to
gain access to equipment in order to perform preventive maintenance tasks.
• This access will be required more often than it is with breakdown-driven maintenance.
• A good program requires the support of production, with immediate notification of any potential problems
and willingness to coordinate equipment availability for inspections and necessary tasks.

41. Maintenance Scheduled.
 Scheduled, fixed-interval preventive maintenance tasks should generally be used only if failures
that cannot be detected in advance can be reduced, or if dictated by production requirements.
 The distinction should be drawn between fixed-interval maintenance and fixed-interval inspection
that may detect a threshold condition and initiate condition-monitoring tasks.
 Examples of fixed-interval tasks include 3,000-mile oil changes and 48,000-mile spark plug
changes on a car, whether it needs the changes or not.
 This may be wasteful because all equipment and their operating environments are not alike.
 What is right for one situation may not be right for another.
Hydraulic System

42. Maintenance Scheduled.
The five-finger approach to maintenance emphasizes elimination and reduction
of maintenance needs wherever possible, inspection and detection of pending
failures before they happen, repair of defects, monitoring of performance
conditions and failure causes, and accessing the equipment on a fixed-interval
basis only if no better means exist.

43. Scheduling techniques:

44. TRIBOLOGY
Tribology is the general term that refers to design and operating dynamics of the bearing-
lubrication-rotor support structure of machinery. Two primary techniques are being used for
predictive maintenance: lubricating oil analysis and wear particle analysis.
Lube Oil Analysis
 Lubricating oil analysis, as the name implies, is an analysis technique that determines the condition of
lubricating oils used in mechanical and electrical equipment.
 It is not a tool for determining the operating condition of machinery or detecting potential failure modes.
 Too many plants are attempting to accomplish the latter and are disappointed in the benefits that are
derived. Simply stated, lube oil analysis should be limited to a proactive program to conserve and extend
the useful life of lubricants.
 Although some forms of lubricating oil analysis may provide an accurate quantitative breakdown of
individual chemical elements—both oil additive and contaminants contained in the oil—the technology
cannot be used to identify the specific failure mode or root-cause of incipient problems within the
machines serviced by the lube oil system.

45. Lube Oil Analysis(Contd.):
 The primary applications for lubricating oil analysis are quality control, reduction of
lubricating oil inventories, and determination of the most cost-effective interval for oil
change. Lubricating, hydraulic, and dielectric oils can be periodically analysed using these
techniques to determine their condition.
 The results of this analysis can be used to determine if the oil meets the lubricating
requirements of the machine or application.
 Based on the results of the analysis, lubricants can be changed or upgraded to meet the
specific operating requirements.

46. Lube Oil Analysis(Contd.):
 In addition, detailed analysis of the chemical and physical properties of different oils used
in the plant can, in some cases, allow consolidation or reduction of the number and types
of lubricants required to maintain plant equipment.
 Elimination of unnecessary duplication can reduce required inventory levels and therefore
maintenance costs.
 As a predictive maintenance tool, lubricating oil analysis can be used to schedule oil change
intervals based on the actual condition of the oil.
 In midsize to large plants, a reduction in the number of oil changes can amount to a
considerable annual reduction in maintenance costs.
 Relatively inexpensive sampling and testing can show when the oil in a machine has
reached a point that warrants change.

47. An Introduction to Total Productive Maintenance (TPM)
 In today’s industrial scenario huge losses/wastage occur in the manufacturing shop floor.
 This waste is due to operators, maintenance personal, process, tooling problems and non-availability of components
in time etc.
 Other forms of waste includes idle machines, idle manpower, break down machine, rejected parts etc. are all
examples of waste.
 The quality related waste are of significant importance as they matter the company in terms of time, material and the
hard earned reputation of the company.
 There are also other invisible wastes like operating the machines below the rated speed, start up loss, break down of
the machines and bottle necks in process.

48.  Zero oriented concepts such as zero tolerance for waste, defects, break down and zero accidents are becoming a
pre-requisite in the manufacturing and assembly industry.
 In this situation, a revolutionary concept of TPM has been adopted in many industries across the world to address
the above said problems.
 This deals in length about this TPM
An Introduction to Total Productive Maintenance (TPM)

49. What is Total Productive Maintenance (TPM)?
 It can be considered as the medical science of machines.
 Total Productive Maintenance (TPM) is a maintenance program, which involves a newly defined concept
for maintaining plants and equipment.
 The goal of the TPM program is to markedly increase production while, at the same time, increasing
employee morale and job satisfaction.

56. IMPORTANCE OF RCM:

57. FLOW CHART FOR RCM

61. ROLE OF AN EFFECTIVE MAINTENANCE ORGANIZATION

64. 1. LINE STAFF ORGANIZAION
 In the line organization, top management has complete control, and the chain of command is clear &
simple.
 Example of line organizations are small business in which the top manager, often the owner, is positioned
at the top of the organizational structure and has clear “lines” of distinction between him and his
subordinates
 A line position is directly involved in the day-to-day operations of the organization, such as producing or
selling a product or service.
 Line positions are occupied by line personnel and line managers.
 Line personnel carry out the primary activities of a business and are considered essential to the basic
functioning of the organization.
 Line managers make the majority of the decisions and direct line personnel to achieve company goals.
 This is called ‘Line Authority’.

65. However, two important clarifications should be considered, however,
when discussing line authority.
1. Line authority does not ensure effective performance, and
2. Line authority is not restricted to line personnel. The head of a staff department has ‘line authority’
over his or her employees by virtue of authority relationships between the department head and his
or her directly reporting employees.
 Staff positions serve the organization by indirectly supporting line functions.
 Staff positions consist of staff personnel and staff managers.
 Staff personnel use their technical expertise to assist line personnel and aid top management in
various business activities.
 Staff managers provide support, advice and knowledge to other individuals in the chain of command.
 Although staff mangers are not part of the chain of command related to direct production of products
or services, they do have some authority over personnel.

66.  ‘Staff Authority’ has the right to advise or counsel those with line authority.
 For example, a human resource development manager advises and aids a production manager or maintenance
manager by training their workmen to improve their skill and capability.
 Therefore, staff authority gives staff personnel the right to offer advice in an effort to improve line operation.
 The line and staff organization combines the line organization with staff departments that support the line
departments.
 Most medium and large-sized firms exhibit line-and-staff organizational structures.
 The distinguishing characteristic between simple line organizations and line-and-staff organizations is the
multiple layers of management within line-and-staff organizations.
 An advantage of a line-and-staff organization is the availability of technical specialists.
 Staff experts in specific areas are incorporated into the formal chain of command.
 A disadvantage of a line-and-staff organization is conflict between line and staff personnel.
 Often, due to different positions and types of authority within a line-and-staff organization, conflict between line
and staff and staff organizational structures, help minimize such conflicts.

67.  Though maintenance as a whole is, often, considered as a staff organization(with production personnel
as line organization), within the maintenance department, we have line organization and staff
organization, thus terming the whole maintenance as a line and staff organization.
 Fig.12.1 shows a typical line and staff organization of Mechanical maintenance department of Alloy
Steels Plant (SAIL), Durgapur, W. Bengal, India.
 It shows the line and staff functions at two different levels.
 At first level, I/c Bar Mill Maintenance, I/c Sheet Mill Maintenance and I/c Hydraulic Cell are staff
functions.
 At next level, Shift/crew in-charge, along with crew workmen are line staff and store keepers and I/c
Planning cell with material chaser etc. are staff organization.

69. Functional Organisation

70. Functional Organisation

72. CENTRALIZED MAINTENANCE ORGANIZATION
DECENTRALIZED MAINTENANCE ORGANIZATION

75. THANK YOU