Deck 17: Maintenance and Reliability

Question 1

Orlando Utilities Commission uses a computerized maintenance management program, and devotes significant dollar and labor resources to power plant maintenance, because the costs of unexpected failure are incredibly high.

Answer 1

True

Question 2

A redundant part or component increases reliability because it is connected in parallel, not in series.

Answer 2

True

Question 3

Reliability is the probability that a machine part or product will function properly for a specified time regardless of conditions.

Answer 3

False

Question 4

Recording the maintenance history of processes, machines, or equipment is important for preventive maintenance, but largely irrelevant for breakdown maintenance.

Question 5

The MTBF distributions of products, machines, or processes that have "settled in," or gone beyond the infant mortality phase, often follow the normal distribution.

Question 6

Failures are tolerable as long as their results are not catastrophic.

Question 7

The reliability of a system in which each individual component must function in order for the entire system to function, and in which each component has its own unique reliability, independent of other components, is the product of the probabilities of each of those components.

Question 8

The "full cost view of maintenance" results in more firms choosing a policy of breakdown maintenance, when compared to the "traditional view of maintenance."

Question 9

If the mean time between failures has been calculated to be 2,000 hours, then FR(N) = 0.0005 failures/unit-hour..

Question 10

The product failure rate is the percentage of failures among the total number of products tested.

Question 11

Maintenance includes all activities involved in keeping a system's equipment in working order.

Question 12

Adding an additional part to a component or product ordinarily reduces reliability by introducing an additional source of failure.

Question 13

Preventive maintenance implies that we can determine when a system needs service or will need repair.

Question 14

Small standard deviations in the MTBF distribution of a machine tend to support a policy of breakdown maintenance for that machine.

Question 15

Infant mortality refers to the high failure rate often encountered in the very early stages of the lifetime of a product.

Question 16

When identifying the optimal maintenance policy, the cost of inventory maintained to compensate for the downtime is a cost often ignored.

Question 17

Preventive maintenance is reactive.

Question 18

A redundant part decreases reliability if the reliability of the redundant part is lower than that of the part it is backing up.

Question 19

The MTBF (mean time between failures) is calculated as the reciprocal of the number of failures during a period of time.

Question 20

Preventive maintenance is nothing more than keeping the equipment and machinery running.

Question 21

A system is composed of three components A, B, and C. All three must function for the system to function. There are currently no backups in place. The system has a reliability of 0.966. If a backup is installed for component A, the new system reliability will be

A) unchanged
B) less than 0.966
C) greater than it would be if a backup were also installed for component B
D) greater than 0.966
E) none of the above

Question 22

Which of the following is a reliability tactic?

A) improving individual components
B) increasing repair speed
C) providing redundancy
D) A and C
E) A, B, and C

Question 23

Simulation models and expert systems are useful tools for enhancing maintenance.

Question 24

Which of the following statements about maintenance at Orlando Utilities Commission is false?

A) There are at least two types of preventive maintenance, including an annual maintenance and a less frequent overhaul schedule.
B) Its preventive maintenance program has earned the company top rankings and its competitive advantage.
C) Each power-generating unit is taken off-line every three years for a complete overhaul.
D) Each of its power-generating units is taken off-line for maintenance every one to three weeks.
E) Costs associated with breakdowns are several times higher than costs arising from preventive maintenance.

Question 25

A system has three components in series with reliabilities 0.9, 0.7, and 0.5. System reliability is

A) 0.315
B) 0.500
C) 0.700
D) 0.900
E) 2.100

Question 26

A job consists of a series of three tasks. Task 1 is performed correctly 98% of the time, task 2 is performed correctly 99% of the time, and task 3 is performed correctly 97% of the time. The reliability of this job is

A) 91.27%
B) 94.11%
C) 97.00%
D) 98.00%
E) 99.00%

Question 27

Components A, B, and C are connected in series. Component D is connected in parallel to component B. Which of the following statements is true?

A) The system works only if A works, B or C works, and D works.
B) Component B must work for the system to work.
C) The system works when A works, C, works, and either B or D works.
D) Components B and C are backups to A.
E) The system works if D works, and any of A, B, or C works.

Question 28

What is the reliability of a four-component product, with components in series, and component reliabilities of .90, .95, .98, and .99?

A) under 0.83
B) 0.90
C) 0.955
D) no less than .99
E) none of the above

Question 29

The objective of maintenance and reliability is to maintain the capability of the system.

Question 30

The objective of maintenance and reliability is to

A) ensure that breakdowns do not affect the quality of the products
B) ensure that no breakdowns will ever occur
C) ensure that preventive maintenance costs are kept as low as possible
D) maintain the capability of the system
E) ensure that maintenance employees are fully utilized

Question 31

What is the reliability of the three components connected in series shown below?

A) 0.799425
B) 0.85000
C) 0.91333
D) 0.95000
E) 2.79

Question 32

While breakdowns occur randomly, their frequency is somewhat predictable through such tools as the product failure rate, MTBF, and the breakdown costs model.

Question 33

A system has three components in parallel with reliabilities 0.9, 0.7, and 0.5. System reliability is

A) 0.315
B) 0.700
C) 0.900
D) 0.985
E) 2.100

Question 34

TPM (total productive maintenance) is an application of TQM (total quality management) principles to the area of maintenance.

Question 35

The probability that a product will function properly for a specified time under stated conditions is

A) functionality
B) maintenance
C) durability
D) reliability
E) fitness for use

Question 36

An optimal maintenance policy strikes a balance between the costs of breakdown and preventive maintenance so that the total cost of maintenance is at a minimum.

Question 37

Consider a product with three components in series, with reliabilities of 0.90, 0.80, and 0.99 for components A, B, and C, respectively. Furthermore, component B uses a backup that also has a reliability of 0.80. What is the reliability of the system?

A) 0.50000
B) 0.71280
C) 0.80000
D) 0.85536
E) 3.49000

Question 38

As the number of components in a system connected in a series decreases, all other things being equal, the reliability of the system usually

A) increases
B) stays the same
C) decreases
D) increases, then decreases
E) decreases, then increases

Question 39

A product has three components, A, B, and C, with reliabilities of 0.95, 0.98, and 0.995. Engineers intend to put a redundant component A that has reliability 0.70. With this change, system reliability will

A) fall by 20%
B) fall by 10% or less
C) rise
D) cannot determine from the information provided
E) none of the above

Question 40

Which of the following best illustrates the importance of employee involvement in achieving successful maintenance and reliability?

A) Operator, machine, and mechanic are independent of one another.
B) Small standard deviations tend to favor preventive maintenance over breakdown maintenance.
C) Infant mortality in products can be decreased through improved owner's manuals and after-sales service and customer training.
D) Employee involvement through such elements as reward systems and power sharing combine with good maintenance and reliability procedures to improve capacity and reduce variability.
E) Empowered operators have higher competence at repairs than field service or depot service.

Question 41

Ten high-technology batteries are tested for 200 hours each. One failed at 20 hours; another failed at 140 hours; all others completed the test. FR(%) is __________ and MTBF is __________.

A) 20%; 880 hours
B) 10%; 1980 hours
C) 20%; 1760 hours
D) cannot calculate from information provided
E) 80%; 920 hours

Question 42

A system is composed of four parts, J, K, L, and M. All four must function for the system to function. The four component reliabilities are .99, .98, .992, and .998. The designers are considering putting a .80 reliable backup at K. This backup will change the system reliability from __________ to __________.

A) 0.9762 to 0.9605
B) 0.9605 to 0.9762
C) 0.9605 to some smaller value
D) cannot be determined
E) none of the above

Question 43

How is MTBF related to FR(N)?

A) MTBF is measured in hours, while FR(N) is measured in years.
B) MTBF is normally distributed, with FR(%) as its mean and FR(N) as its standard deviation.
C) MTBF is the reciprocal of FR(N).
D) Both MTBF and FR(N) increase when breakdown maintenance is replaced by preventive maintenance.
E) MTBF and FR(N) are unrelated concepts.

Question 44

Ten high-technology batteries are tested for 200 hours each. One failed at 50 hours; all others completed the test. FR(%) is __________ and FR(N) is __________.

A) 10%; 1/1850
B) 10%; 1/2000
C) 25%; 1850 hours
D) 90%; 1/2000
E) Indeterminate; no standard deviation is given.

Question 45

The process that involves repair on an emergency or priority basis is known as

A) breakdown maintenance
B) emergency maintenance
C) failure maintenance
D) preventive maintenance
E) priority maintenance

Question 46

For a machine to be a good candidate for preventive maintenance

A) the consequences of failure must exceed the cost of preventive maintenance and the MTBF distribution must have a large standard deviation
B) the consequences of failure must exceed the cost of preventive maintenance and the MTBF must be relatively low
C) the consequences of failure must exceed the cost of preventive maintenance and the MTBF distribution must have a relatively low standard deviation
D) the consequences of failure must exceed the cost of preventive maintenance and the MTBF must be relatively high
E) the consequences of failure must be relatively unknown and, therefore, risky

Question 47

Suppose that a process is comprised of multiple components, each having a 75% success rate. What is the change in reliability going from a series layout to a parallel layout if the process has 5 components?

A) 0%
B) 100%
C) 76.2%
D) -76.2 %
E) unable to determine

Question 48

An oil change is to ____________ maintenance as repair of a broken alternator is to ____________ maintenance.

A) preventive, breakdown
B) breakdown, preventive
C) preventive, preventive
D) breakdown, breakdown
E) none of the above

Question 49

A manager is comparing the total maintenance (preventive plus breakdown) cost curves for two scenarios. The graphs have maintenance commitment on the x-axis and costs on the y-axis. Scenario A includes the direct breakdown maintenance costs, while Scenario B includes the "full" (direct and indirect) breakdown maintenance costs. Which of the following should the manager notice when going from Scenario A to Scenario B?

A) total cost is decreased
B) optimal point is moved to the left
C) optimal point is moved to the right
D) preventative maintenance cost slope is increased
E) none of the above

Question 50

As far as maintenance costs are concerned,

A) for low levels of maintenance commitment, breakdown maintenance costs exceed preventive maintenance costs
B) for low levels of maintenance commitment, preventive maintenance costs exceed breakdown maintenance costs
C) for high levels of maintenance commitment, breakdown maintenance costs exceed preventive maintenance costs
D) preventive maintenance is always more economical than breakdown maintenance
E) Breakdown maintenance is always more economical than preventive maintenance when the "full cost of breakdowns" is taken into consideration.

Question 51

Which one of the following statements about maintenance is true?

A) The optimal degree of preventive maintenance is associated with zero breakdowns.
B) Breakdown maintenance is proactive.
C) Preventive maintenance is reactive.
D) Preventive maintenance is limited to keeping machinery and equipment running.
E) Human resources are a major component of effective maintenance management.

Question 52

Infant mortality in electronics follows which kind of distribution?

A) normal
B) negative exponential
C) exponential
D) random
E) one-sided normal distribution

Question 53

A two-component process has an 81% success rate in series and a 99% success rate in parallel. If each component has the same reliability, what is the reliability of an individual component?

A) 50%
B) 90%
C) 99%
D) none of the above
E) unable to determine

Question 54

As a firm's maintenance commitment increases,

A) the breakdown maintenance costs increase and the preventive maintenance costs decrease
B) both the breakdown maintenance costs and the preventive maintenance costs decrease
C) the breakdown maintenance costs decrease and the preventive maintenance costs increase
D) both the breakdown maintenance costs and the preventive maintenance costs increase
E) None of the above is true.

Question 55

Ten high-technology batteries are tested for 200 hours each. One failed at 20 hours; all others completed the test. FR(%) is __________ and MTBF is __________.

A) 10%; 1/1820
B) 90%; 1/1820
C) 10%; 1820 hours
D) 10%; 1980 hours
E) cannot calculate from information provided

Question 56

MTBF measures the average

A) calendar time between failures
B) operating time between failures
C) number of failures per unit time
D) number of operations between failures
E) downtime per breakdown

Question 57

Suppose that the introduction of a preventive maintenance program is deemed cost effective. Which of the following is most likely true if the cost to actually perform preventive maintenance is very expensive?

A) high standard deviation in MTBF
B) low standard deviation in MTBF
C) low Cost to Repair
D) repairs carry little non-monetary consequences
E) the system never fails

Question 58

The normal distribution is an appropriate model of

A) the high initial failure rates of product, machine, or processes
B) system reliability where components are connected in series
C) system reliability where components are connected in parallel
D) the MTBF distribution of products, machines, or processes that have "settled in"
E) the full cost view of maintenance

Question 59

The MTBF distribution of a machine that has passed the phase of early failures exhibits a normal distribution. The smaller the standard deviation of this distribution

A) the more expensive is preventive maintenance
B) the more likely this machine is a candidate for preventive maintenance
C) the shorter is the time interval between breakdowns
D) the more likely this machine will break down
E) the more likely this machine will be maintained by a breakdown maintenance policy

Question 60

Infant mortality refers to which one of the following examples?

A) high frequency on the left side of the MTBF distribution
B) failure of items used in the nursery ward of a hospital
C) failure of products with a very short life cycle
D) market failure of brand new products
E) high failure rate often encountered in the very early stages of the lifetime of a product

Question 61

__________ consists of all activities involved in keeping a system's equipment in working order.

Question 62

When depot service is compared to operator maintenance,

A) operator maintenance is slower than depot service
B) competence is higher, but costs may also be higher, with depot service
C) depot service is often the weak link in the chain because of the lack of specific training
D) depot service occurs on-site, while operator maintenance occurs off-site
E) depot service is better for systems connected in parallel, while operator maintenance is preferred for systems connected in series

Question 63

__________ is a plan that involves routine inspections, servicing, and keeping facilities in good repair to prevent failure.

Question 64

Techniques for enhancing maintenance can include

A) simulation of breakdowns from prolonged use
B) expert systems that aid in problem-solving
C) automated sensors that warn when preventative maintenance is required
D) A and C
E) A, B, and C

Question 65

DuLarge Marine manufactures diesel engines for shrimp trawlers and other small commercial boats. One of their CNC machines has caused several problems. Over the past 30 weeks, the machine has broken down as indicated below. What is the expected number of breakdowns per week?

A) 1
B) 2
C) 6
D) 10
E) 30

Question 66

The inverse of the mean time between failures is the __________.

Question 67

The __________ takes into account such costs as deteriorated customer relations and lost sales.

Question 68

DuLarge Marine manufactures diesel engines for shrimp trawlers and other small commercial boats. One of their CNC machines has caused several problems. Over the past 30 weeks, the machine has broken down as indicated below. Each time the machine breaks down, the firm loses an average of $3,000 in time and repair expenses. If preventive maintenance were implemented, it is estimated that an average of only one breakdown per week would occur. The cost of preventive maintenance is $1,000 per week. What is the weekly total maintenance cost of this program?

A) $1,000
B) $3,000
C) $4,000
D) $6,000
E) $8,000

Question 69

Which of the following increase as repairs move from the maintenance department to the depot service?

A) cost
B) replacement time
C) quality
D) employee ownership
E) A, B, and C

Question 70

Autonomous maintenance occurs when

A) employees are empowered to observe, check, adjust, clean, and notify
B) a remote computer system signals the need for breakdown maintenance
C) a remote computer system signals the need for preventative maintenance
D) employees perform their own breakdown maintenance
E) none of the above

Question 71

__________ is the use of a component in parallel to raise reliabilities.

Question 72

__________ is the failure rate early in the life of a product or process.

Question 73

Which one of the following is not necessary to identify the optimal maintenance policy?

A) historical data on maintenance costs
B) cost of performing the analysis
C) breakdown probabilities
D) breakdown occurrences
E) repair times

Question 74

__________ combines total quality management with a strategic view of maintenance from process equipment design to preventive maintenance.

Question 75

DuLarge Marine manufactures diesel engines for shrimp trawlers and other small commercial boats. One of their CNC machines has caused several problems. Over the past 30 weeks, the machine has broken down as indicated below. Each time the machine breaks down, the firm loses an average of $3,000 in time and repair expenses. What is the expected breakdown cost per week?

A) $1,000
B) $2,000
C) $6,000
D) $10,000
E) $60,000

Question 76

Which of the following costs tend to be ignored in determining the optimal maintenance policy?

A) expected breakdown costs
B) preventive maintenance costs
C) the costs associated with various levels of commitment to maintenance
D) cost of low morale
E) all of the above

Question 77

Which of the following is true regarding total productive maintenance (TPM)?

A) TPM is concerned with machine operation, not machine design.
B) Field service and depot service perform virtually all maintenance and repair activities.
C) Operators run their machines, but maintenance departments maintain them.
D) TPM reduces variability through employee empowerment and excellent maintenance practices.
E) TPM views maintenance and repair as tactical issues, not strategic ones.

Question 78

Describe how Orlando Utilities Commission obtains competitive advantage through its maintenance practices.

Question 79

__________ is the expected time between a repair and the next failure of a component, machine, process, or product.

Question 80

__________ is the probability that a machine part or product will function properly for a specified time under stated conditions.