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CRE Sample Test #4.

1. Which of the following is (are) NOT (a) failure mechanism (s) ?

. Cracked.

. Over-stressing.

. Inadequate maintenance instructions.

. Oxidized.

A. l and lV B. ll and lll C. l D. lll

2. Which answer correctly describes the experimental design on the left ?

A. Greaeco-Latin Square.

B. Latin Square.

C. Randomezed Complete Block.

D. Youden Square.

3. A test sample of 50 tires are operated under simulated driving conditions to 20% tread depth. What is

the 95% lower reliability limit for tread wear with a 90% level of confidence, if the tires exhibited a mean

mileage to limit tread depth of 57,000 miles and a standard deviation of 8,000 miles ?

A. 44,893 miles. B. 42,392 miles. C. 39,453 miles. D. 41,622 miles.

4. With regard to the reliability bathtub curve, which of the answers does NOT fit with the others ?

A. Useful lif. B. Exponentially distributed reliability function.

C. Wearout. D. Constant failure rate.

5. Extensive reliability testing must be conducted on products to ensure functional, environmental, reliability

and safety features. Which of the following techniques can be most useful for highlighting unknown failure

modes ?

A. Use experienced test personal. B. Use specific guidelines.

C. Use typical customers. D. Use selected features.

6. In the Taguchi design methodology, what are noise factors ?

A. Factors that strongly influence the mean response. B. Factors that impact tolerance design.

C. Factors that maximize parameter design. D. Factors that influence variation in the output.

7. Pascal's triangle presents a simple means of determining which of the various terms of the binomial

expansion ?

A. Exponents. B. Coefficients.

C. Combinations. D. Permutations.

8. A redundant system has 5 standby parallel components, with perfect switching. If each of the

components have a reliability of 0.03 failures/hour, what is the system's reliability at 20 hours ?

A. 0.9232 B. 0.9432 C. 0.9997 D. 0.9999

9. DFX has many internal and external customer based objectives. Which of the following would be

considered an external target ?

A. Design for assembly. B. Design for features.

C. Design for testability. D. Design for manufacture.

10. One method of evaluating the design reliability is to analyze the design assuming the worst case.

Which of the following techniques is NOT applicable for worst case analysis ?

A. Root-sum squared. B. Extreme value C. Eyring model D. Monte Carlo

11. Sequential life testing plans can be based on which of the following distributions?

. Binomial.

. Weibull.

. Exponential.

. Monte Carlo.

A. I and II only B. II and III only C. I, II and III only D. I, II, III and IV

12. A company has a problem with damage to fragile assemblies during component handling and parts

storage. Which of the following is the BEST way to detect the cause of this problem ?

A. Perform a fault-tree analysis. B. Perform process reliability audits.

C. Assign the control to area supervision. D. Train employees and supervisors on requirements.

13. During a determination of either cumulative or instantaneous mean time between failure, an engineer

uses a rate of growth slope of 0.7. One would conclude that :

A. A top priority improvement program is in effect.

B. An above average reliability improvement exists.

C. Below average reliability improvement exists.

D. The engineer has made a faulty assumption.

14. Which of the following is NOT a widely recognized topic area of DFX ?

A. Design for profit. B. Design for assembly.

C. Design for reliability D. Design for appearance.

15. What is(are) the prime purpose(s) of a failure reporting, analysis and corrective-action system ?

. To determine the root cause of the problem.

. To record the corrective action taken.

. To document the problem.

. To assure proper product quality.

A. I only B. II and III only C. I, II and III only D. I, II, III and IV

16. In a manufacturing situation, an engineer has an opportunity to design new machinery. Automated

machinery is BEST applied under which of the following conditions ?

. Those involving continuous repetitive processes.

. Those requiring various degrees of originality.

. Those requiring a very quick reaction to stimuli.

. Those requiring an interpretation of collected data.

A. I and II only B. II and III only C. I and III only D. II, III and IV only

17. The ratio of the total operating time to the total number of failures is :

A. Maintenance action rate. B. Maintainability.

C. Failure rate. D. Mean time to failure.

18. What kind of failure would MOST likely result from insufficient hardware debugging ?

A. Wear out failure. B. Random failure.

C. Early failure. D. Catastrophic failure.

19. Which of the following techniques provides a means of translating customer requirements into

appropriate technical requirements ?

A. Concurrent engineering. B. Quality function deployment.

C. Benchmarking. D. Total quality management.

20. Which of the following should be avoided in parts selection to enhance the design reliability ?

A. Selection of standard parts. B. Selection of exotic technology parts.

C. Selection of redundant parts. D. Selection of high reliability parts.

21. Consideration for proper part selection are :

. Parts application and specification.

. Selection, control and integration.

. Derating.

A. l and ll only B. l and lll only C. ll and lll only D. l, ll and lll

22. Why is reliability prediction performed ?

. To identify and predict safety issues.

. To determine the estimated life of the device.

. To identify the weakest component of the system.

. To predict sales revenue in order to set the development budget.

A. I, II and IV only B. II, III and IV only C. I, II and III only D. I, II, III and IV

23. Which of these reliability terms applies to non-repairable devices ?

A. MTBF. B. Hazard rate. C. Occurrence rate. D. MTBMA.

24. System and cost effectiveness analysis outputs :

. Can be used to determine the best balance of system performance, cost and schedule.

. Do not guide trade-off decisions.

. In most cases will not identify the degree to which innovations should be pursued.

. Will not guide preliminary design features.

A. I only B. II only C. III only D. IV only

25. Failure rate is :

. Pertinent to only repairable devices.

. Commonly referenced to a time or cycle standard.

. The reciprocal of MTTF.

. The reciprocal of MTBF.

. The reciprocal of MTBD.

A. II and III only B. II, III and IV only C. I, II, and IV only D. I, II and V only

26. Of the following, which is the MOST important reliability principle ?

A. Use only proven design. B. Specify only high reliability components.

C. Consider reliability early in the design phase. D. Use redundancy throughout the design.

27. The purpose of derating parts is to :

. Increase part life.

. Enhance overall system reliability.

. Improve circuit design.

A. I only B. I and II only C. II and III only D. I, II and III

28. In determining the allocation of function to humans and equipment :

A. Allocate all major functions to the equipment.

B. Allocate all major functions to the human.

C. Allocate functions to optimize the workload on the human.

D. Allocate functions to optimize system performance.

29. Why must statistical data be used carefully in reliability applications ?

. The variability of data makes it unreliable.

. Valid data is expensive to collect.

. Variation occurs over time.

. Useable data is not plentiful.

A. I, II, III and IV B. I, II and III only C. II and III only D. I only

30. A first step in the FMECA is to :

A. Define the system requirement. B. Compile a critical items list.

C. Identify failure modes. D. Establish ground rules to which the FMECA is performed.

31. A certain equipment has a MTBF of m = 300 hours. Assuming an exponential distribution of time to

failure, what is the maximum time of allowable operation if a reliability of 0.999 is required ?

A. 30 hours. B. 0.3 hours. C. 300 hours. D. 0.003 hours.

32. A system is principally dependent upon the operation of one particular critical units. It was therefore

designed with three additional such units in standby redundancy, where a standby unit goes into operation

as soon as the preceding unit fails. Each of these units has a constant failure rate during operation. The

units fail independently and the system fails when the last standby unit fails. An appropriate time-to-failure

distribution for this system is the :

A. Lognormal. B. Exponential. C. Gamma. D. Weibull.

33. The variations which the normal distribution curve describes are due to :

A. Non assignable causes. B. Catastrophic failure.

C. Assignable causes D. Degradation failure.

34. The purpose of a failure reporting, analysis and corrective action system (FRACAS) includes which

two of the following ?

. Provide a closed loop failure reporting system.

. Provide initial robust product designs.

. Provide management with derating methods and principles.

. Provide a failure analysis and corrective action vehicle.

A. I and II only B. II and III only C. I and IV only D. II and IV only

35. Probability ratio sequential tests are used for products designed to operate for a long period of time.

This test is primarily based on :

A. The ratio of an acceptable MTBF to an unacceptable MTBF.

B. Accept regions versus reject regions.

C. Type I versus type II errors.

D. Truncation of test results.

36. A mission profile is :

. Time-phased.

. A summary of events and environments.

. All activities from initiation to completion of a mission.

A. I and III only B. II and III only C. III Only D. I, II and III

37. The means of large samples from a population tend to be normally distributed around the population

mean. This statement is TRUE according to which of the following theorems ?

A. Central limit. B. Camp-Meidal. C. Tchebysheff's. D. Least squares.

38. When reliability people say they are breaking the monopoly of the designer they mean

A. They are relieving the designer of his/her responsibility for the design.

B. They insist on having final approved of the design.

C. They intend to put the reliability engineer organizationally higher than the design engineer.

D. They intend to review the design in conjunction with other experts.

39. Development of reliability demonstration tests for electronic equipment should consider :

. Functional operation of the equipment

. Use environments

. Test criteria for operational parameters

A. I only B. I and II only

C. I and III only D. I, II and III

40. Which actions are used to develop mathematical formulas for determining a system's reliability ?

. Identify system elements and their function.

. Test the system elements.

. Develop mathematical formulas for the system.

. Incorporate system constants into the mathematical relationships.

. Substitute element probabilities into the mathematical formulas.

A. I and II only B. I, II and V only C. I, III and IV only D. I, II, III, IV and V

41. Data collection for a failure reporting, analysis, and corrective action system is important. The control

of input data is BEST determined by :

A. The use of a form. B. Possible cause identification.

C. Training of data collectors. D. A failure review board.

42. Which of the following are characteristics of the step-stress testing technique ?

. Elevated stress levels are used.

. Fixed stress levels are established.

. Stress is incrementally increased.

. Multiple stresses can be used.

A. I only B. II and III only C. I, III and IV only D. I, II, III and IV

43. Design reviews should be held :

A. During the design phase. B. At each critical design program milestone.

C. At least once a year. D. After the design is completed.

44. The main reason for the use of Quality Function Deployment (QFD) is which of the following ?

A. To implement the voice of the customer.

B. To ensure concurrent engineering.

C. To assign responsibilities for product designs.

D. To provide a structured product design approach.

45. If the probability density function of some measurements is found to be 0.02 x for x equal 0 to 10.

What is the probability that a measurement will be between 4 and 5 ?

A. 0.01 B. 0.05 C. 0.09 D. 0.20

46. The most important reason(s) for performing design reviews is to :

. Identify the anticipated field usage of the system

. Review referenced specifications to be used during procurement

. Follow up the outcome of action items discussed during prior meetings

A. I only B. II only C. I and III only D. I, II and III

47. A failure that occurs without being caused by the failure of any other item is known as :

A. An independent failure. B. A dependent failure.

C. An intermittent failure. D. A pattern failure.

48. Which of the following is NOT a primary objective of system burn-in ?

A. Screen infant mortality defects. B. Improve the customer's perceptions.

C. Identify defective parts. D. Correct design problems.

49. Which of the following reliability tests is conducted during the prototype stage ?

A. Demonstration test. B. Qualification test.

C. Acceptance test. D. Screening test.

50. The optimum cost point for total life cycle costs occurs :

A. When operations and maintenance costs are minimized.

B. When reliability program expenditures are maximized.

C. When acquisition costs plus ongoing costs are minimized.

D. When manufacturing and development costs are minimized.

51. Six independent samples are taken of smokestack gas. The mean value of a critical pollutant was

30.2 ppm for the six samples, with a standard deviation s = 5 ppm. Assuming that the samples were

taken at random times, what is the 90% confidence interval for the proportion of the critical pollutant in

the smokestack gas ?

A. 30.2 ± 4.11ppm B. 30.2 ± 3.96 ppm C. 30.2 ± 4.00 ppm D. 30.2 ± 3.36 ppm

52. The software test design method that involves seeding errors into a program is known is :

A. Test cases. B. Fault insertion and error handling.

C. Equivalent class partitioning. D. Customer defect reports.

53. Burn-in testing is performed to accomplish which of the following objectives ?

. Test 100% of devices.

. Provide higher field reliability.

. Recycle more devices to rework.

A. I only B. II only C. I and II only D. I, II and III

54. A 2 level 5 factor experiment is being conducted to optimize the reliability of an electronic control

module. A half replicate of the standard full factorial experiment is proposed. The number of treatment

combinations will be

A. 10 B. 12 C. 16 D. 32

55. What is the reliability of the power switching system schematic on the left after 30,000 hours ? The

electric utility primary power system (A) has a failure rate of 0.00001 failure/hour. The motor generator

backup system (B) has a failure rate of 0.0007 failure/hour. The standby system has an imperfect switch

with 0.90 reliability per operation.

A. 0.75 B. 0.80 C. 0.87 D. 0.83

56. A highly accelerated stress screening (HASS) test can help to detect and separate units with

manufacturing defects. HASS test limits are typically developed from :

A. Production reliability acceptance tests. B. Statistical process control data.

C. Highly Accelerated Life Tests. D. Bayesian reliability testing.

57. Severity classifications are assigned to the potential consequences of a failure. If a resulting failure

could cause a minor injury to personnel, which category would best describe it ?

A. Category I - Catastrophic. B. Category II - Critical.

C. Category III - Marginal. D. Category IV - Minor.

58. Test, analyze and fix (TAAF) programs typically include :

. Failure Reporting and Corrective Action System (FRACAS).

. Reliability Growth Testing (RGT).

. Environmental Stress Testing (ESS).

. Failure free qualification testing.

A. l and ll only B. ll and lll only C. l, ll and lll only D. All of the above.

59. A new interface board for gateway access to the internet is being developed. Consideration of

combined environmental reliability testing should include all of the following factors EXCEPT :

A. Electromagnetic inference. B. Temperature cycling.

C. Vibration testing. D. Equipment compatibility.

60. A reliability engineer has developed an accelerated life testing plan. An exponential distribution is

assumed. Given that the acceleration factor is 2.4, a test provides a MTTF of 80 hours. Determine the

reliability under normal conditions for a time equal to 200 hours.

A. 8.2 % B. 19.7 % C. 35.3 % D. 45.7 %

61. Nonrelevant failures include all of the following EXCEPT :

A. Unverified failures. B. Mishandling failures.

C. Operating adjustment failures. D. Human error failures.

62. For continual improvement in product reliability which of the following tests is MOST desirable ?

A. Development tests. B. Burn-in tests

C. Stress screening tests D. Qualification tests.

63. Human factors field testing :

A. Should be carried out on a production model of the equipment.

B. Should demonstrate the capability of personnel to perform the required function.

C. Does not require a plan if military personnel are involved.

D. Must not be combined with engineering tests on the same equipment.

64. An electrical sneak circuit is BEST described as :

A. A electrical surge test. B. More than one electrical executable path.

C. An invalid latent path. D. A perpetual circuit loop.

65. Which one of the following will NOT increase reliability in design ?

A. Deterating techniques. B. Design redundancy.

C. Designing for maintainability. D. Acceptance testing.

66. The process of dividing up or budgeting the final reliability goal among the subsystem is known as :

. Reliability allocation.

. Reliability prediction.

. Reliability apportionment.

A. l only B. l and lll only C. ll and lll only D. lll only

67. The reliability of a complex system can BEST be improved by :

A. Selecting system components objectively.

B. Multiple system testing ( > 15 systems).

C. Well designed and executed preventive maintenance system.

D. Including redundant concepts in design.

68. When a large number of components have been tested for a fixed time with no failure then :

A. The failure rate is indeterminable.

B. The failure rate is at least an individual test time.

C. The failure rate is equivalent to the sum of the individual test times.

D. The Laplace rule of succession will apply.

69. To estimate the individual part failure rate using the parts stress method which of the following is

necessary ?

. Part base failure rate.

. Environmental stress factor.

. Part quality factor.

A. l and ll B. l and lll only C. ll and lll only D. l, ll and lll

70. Monte Carlo simulation to evaluate performance of a system from component information can be

advantageously used even in situation where :

. The system is complex.

. The components are interrelated.

. A small estimating error is required.

A. l only B. l and lll only C. ll and lll only D. l, ll and lll

71. An elementary element of any age control on rubber products would be :

A. Date received. B. Date installed. C. Date cured. D. Date ordered.

72. Source(s) of field failure data include :

. Warranty returns.

. Customer complaints.

. Field representative information.

. Tests on purchased items.

A. l and ll only B. ll and lll only C. l, ll and lll only D. l, ll, lll and lV

73. If the exponential distribution is assumed, what is the reliability prediction uncertainty ?

A. The uncertainty is equal to the standard deviation of the normal distribution.

B. The uncertainty is equal to the square of the standard deviation of the normal distribution.

C. The MTBF.

D. The reliability prediction is a probabilistic determination, so uncertainty does not apply.

74. Concurrent engineering means :

A. Alternate design being generated in parallel.

B. Engineers working in tandem shifts to speed to the process.

C. An electrical engineering term.

D. Use of inputs from all technical disciplines early and simultaneously.

75. Which of the following is required to establish a reliability specification ?

A. The usage environment. B. The system quality.

C. The reliability policy. D. A reliability model.

76. According to the definition of reliability, performance, over the expected or intended life, is one

criterion. In order to obtain a measurement for reliability, the actual life (t) must be compared to which of

the following ?

A. Test cycles. B. Required life. C. MTBF D. Probability of failures.

77. Risk management activities do NOT include :

A. Identify the hazard. B. Rating the hazard.

C. Controlling the hazard. D. Identifying similar hazards on other products.

78. The most cost effective system is the least expensive system which will provide :

. Maximum performance.

. Maximum reliability, durability and survivability.

. Maximum maintainability and operational readiness within the planned logistic system.

. A reasonable balance among the factors listed in I, II, and III above.

A. I only B. II only C. III only D. IV only

79. While testing a new design, you experienced 3 failures in 100 tests. What is the lower confidence

limit for the unit's tested reliability based on a confidence level of 0.90?

A. 0.962 B. 0.950 C. 0.935 D. 0.925

80. Which of the following are risk assessment methods ?

. FMEA and FTA.

. Delphi and MOSAR.

. HAZOP and Severity.

. What-If and User focus reviews.

A. l, ll and lll only B. ll, lll and lV only C. l and lV only D. All of the above.

81. Product safety standards do NOT include :

A. Product requirements laws passed by governments.

B. Requirements for general, equipment and component safety.

C. Performance requirements for products.

D. Evaluation requirements for product safety testing.

82. Your company has just installed a new computer data entry system and you must determine the new

input error rates. Management requires you to report the error rate within 0.5%, at a 95% confidence

level. What sample size do you need if the population standard deviation is 1.2% ?

A. 15 B. 16 C. 22 D. 23

83. Which of the following failures would probably be considered a chargeable reliability failure ?

A. A nonrelevant failure. B. A repair induced failure.

C. A failure beyond expected life and not replaced. D. An unverified failure.

84. Design reviews should have sufficient information available to make their meetings worthwhile. Formal

controls (specifications, drawing controls, etc.) should begin with the first design review. This approach is

referred to as :

A. Configuration control. B. Documentation control.

C. Quality systems documentation. D. Standards organization.

85. Extensive reliability testing must be conducted on products to ensure functional, environmental,

reliability and safety features. Which of the following techniques can be most useful for highlighting

unknown failure modes ?

A. Use experienced test personnel. B. Use specific guidelines.

C. Use selected features. D. Use typical customers.

86. Which of the following can be used to determine the MTTR?

A. Mean time between maintenance actions.

B. Mean time between failures and potential availability.

C. Mean maintenance action time.

D. Mean time between failures.

87. A FMECA that analyzes how a device performs rather than the characteristics of the specific

components can be referred to as :

. A functional FMECA.

. A hardware FMECA.

. A black box FMECA.

. A criticality analysis.

A. I only B. I and III only C. II and III only D. I, II, III and IV

88. Reliability objectives and requirements should be set in which of the following life cycle phases ?

A. Concept and design. B. Validation and test.

C. Operation and repair. D. Full scale design and development.

89. An employee is injured on the job. The employer has proven to have a good safety and health

program. Generally the employee has which of the following options available to him/her ?

A. Contributory negligence. B. Caveat emptor.

C. Workman's compensation. D. Caveat venditor.

90. Design plans are BEST developed for product reliability with significant input from which of the

following ?

A. Quality management. B. General management.

C. The project team. D. Reliability management.

91. In specially designed test environments, devices can be analyzed against more than one

environmental condition. This type of reliability testing is known as :

A. Joint environmental reliability testing. B. Multiple environmental reliability analysis.

C. Combined environmental reliability testing. D. ANOVA environmental reliability testing.

92. A design review committee has recommended changes to a proposed design. Whose job is it to

investigate and incorporate the ideas that will aid product reliability ?

A. The design review chairman. B. The senior decision maker.

C. The reliability engineer. D. The design engineer.

93. In the planning and usage stages of a test, analyze and fix program, it is very important to :

. Accept some failures as nonrelevant.

. Fully analyze all failures.

. Dismiss no failure as random.

. Take corrective action on all failures.

A. I only B. II and III only C. II, III and IV only D. I, II, III and IV

94. In a design team environment, the reliability function can influence product reliability principally by :

A. Integrating the reliability requirements into product design.

B. Developing reliability tests and procedures.

C. Conducting internal and external failure analyses.

D. Providing repair and maintenance service information.

95. To conduct accelerated life tests, which of the following assumptions must be made ?

. The severity of the stress levels does not change the life distribution.

. The Arrhenius model is normally followed.

. The relationship between the stress level and the life distribution is known and valid.

. The testing is conducted at a stress level equivalent to or near failure conditions.

A. I only B. I and III only C. II and III only D. I, II, III and IV

96. A component has a strength of 8000 psi and a standard deviation of 1200 psi. It needs to withstand

a load with a mean value of 5000 psi and a standard deviation of 500 psi. Both strength and load are

normally distributed. What is the probability of failure for the component ?

A. 0.0174 B. 0.0104 C. 0.0059 D. 0.0014

97. Products should be subjected to tests which are designed to :

. Demonstrate the basic function at a minimum testing cost.

. Approximate the conditions to be experienced in customer's application.

. Assure that specifications are met under laboratory conditions.

. Assure performance under severe environmental conditions.

A. I only B. II only C. III only D. IV only

98. A reliability engineer should develop expertise in :

. The interpretation and use of certain military specification.

. Communication and presentation methods.

. Financial analysis and justification techniques.

A. l only B. l and ll only C. l and lll only D. l, ll and lll

99. One of the descriptions of component failures can be explained by a mathematical model with a

formula showing that the rate of chemical reaction varies exponentially with a rise in operating

temperature. This law is known as the :

A. Planck Law. B. Pareto Law. C. Arrhenius Law. D. Poisson Law.

100. The hazard function is :

. The probability of failure during a very small time interval, assuming a failure occurs before that

time.

. A function of constant failure rate only.

. A function of increasing failure rate only.

. The ratio of the probability density function to the reliability function.

A. I only B. II only C. III only D. IV only

101. Which answer provides the MOST useable order for the following training program development steps

?

. Evaluate and reinforce training results.

. Identify training objectives.

. Select training methods and techniques.

. Assess training needs.

. Implement the training program.

A. IV, II, III, V, I B. IV, III, II, V, I C. II, IV, III, V, I D. II, III, V, IV, I

102. A non-repairable device that exhibits a history of failures consistent with a constant hazard rate,

suddenly fails prematurely. Which of the options might be a possible cause for the failure ?

A. Material fatigue caused by cyclic loading. B. Burn-in.

C. Overload situation. D. Substandard manufacturing quality.

103. A randomly selected sample of bicycle helmets was tested for impact resistance. Given the data

results below, what is the 95% confidence interval for the mean bicycle helmet impact resistance ?

Test results:

Sample size: 100 helmets.

Average impact resistance: 276 Gs.

Standard deviation of the measurements: 15 Gs.

A. 276 ± 29.4 Gs B. 276 ± 2.47 Gs C. 276 ± 2.94 Gs D. 276 ± 2.17 Gs

104. Which of the following characteristics are essential for a successful design review team ?

. Multi-disciplined functionality.

. Possess change authority.

. Membership limited to design engineering and reliability engineering.

. Functions as a investigative research team only.

A. I and II only B. II and III only C. III only D. I, III and IV only

105. If the probability of a car starting on a sub-zero morning is 0.6, and we have two such cars. What

is the probability that at least one of the cars will start on a sub-zero morning ?

A. 0.92 B. 0.84 C. 0.81 D. 0.60

106. Reliability testing of parts is performed to obtain which of the following types of information ?

. Application suitability.

. Environmental capability.

. Measurement of life characteristic.

A. I only B. II only C. I and II only D. I, II and III

107. In general, one should select the highest component parameter ratings feasible so that :

. Failure rates may be minimized.

. Probability of secondary failure is minimized.

. Safety margins are offered against unforeseen transients.

A. I only B. I and II only C. I and III only D. I, II and III

108. A component has a constant failure rate of 0.0005 failures per hour. What is the reliability for 1,000

hours of operation assuming wearout is not a factor ?

A. 0.995 B. 0.500 C. 0.373 D. 0.607

109. Given the sample data: 5, 15, 10, 7, 20. What is the unbiased estimator of the sample variance ?

A. 27.50 B. 29.84 C. 37.30 D. 46.62

110. Minimum requirements for the organization's reliability manual include :

. Design review and test procedures.

. Responsibility for specific programs.

. Company definition of process control.

. Internal audit policy.

. Statement of reliability policy.

A. I, II and V only B. II, III and V only

C. I, II, IV and V only D. I, II, III, IV and V

111. Equipment and machinery do break down and require repairs over time. As plant engineer, which of

the following guidelines should you follow ?

. Keep the repair rate as low as possible.

. Keep the failure rate as low as possible.

. Keep the repair rate as high as possible.

. Keep repair times independent of required production time.

A. I and II only B. II and III only C. II and IV only D. I, II and III only

112. The effectiveness of a maintenance program is affected MOST by :

A. Availability of spare parts.

B. Designed ease of installation and removal of components.

C. Reliability of installed, replaceable items.

D. Skill level of the maintenance personnel.

113. The House of Quality incorporates a correlation matrix roof. This describes the relationships between

which of the following ?

A. Hows [design features]. B. Whats [customer needs].

C. Whats and hows. D. Competitive comparisons.

114. Once a new system is approved for design, a criticality analysis (CA) should be performed. A proper

design sequence could be as follows :

. Quantify the probability of failure of each risk.

. Describe the system and draw up an inventory of parts.

. Determine the criticality of the consequence of a failure.

. Trace all risks associated with the system.

A. IV, II, I, III B. II, I, III, IV C. I, II, III, IV D. II, IV, I, III

115. Many actions to correct failure modes do NOT succeed because they have focused on which of the

following ?

. A symptom of the problem.

. An apparent cause of the problem.

. The root cause of the problem.

. The immediate cause of the problem.

A. I only B. II and III only C. I, II and IV only D. I, II, III and IV

116. A critical items list is used to highlight items that could have an appreciable effect on the product's

reliability. It is evolved from :

A. A summary shown by other analyses to be critical. B. The judgement of a reliability engineer.

C. A top management critique. D. Pareto analysis results.

117. Your customer required a paper cutting machine with these specifications :

Speed : 100m/minute; Cutting width : 47 inches; Good product : 99%.

You deliver a machine to this customer with these specifications :

Speed : 110m/minute; Cutting width : 48 inches; Good product: 97%.

How would you classify this success/failure ?

A. A technical success, but quality failure. B. A limited success.

C. A technical failure. D. None of the above.

118. The design phase of equipment :

. Is too early to make a human factors analysis of associated procedures.

. Is the first place to analyze the operating procedure requirements.

. Does not require an analysis of operating procedures because equipment design will change during

test and production.

. Would not permit the design engineer and human factors specialist to develop equipment operating

procedures.

A. I only B. II only C. III only D. IV only

119. Which of the following is NOT a major management product safety responsibility ?

. Formulate a product safety policy.

. Promote employee safety through training and education.

. Assure that a mechanism exists to segregate and dispose of any non-conforming product.

. Ensure that the company complies with all product safety standards and liability laws.

A. I only B. II only C. III only D. IV only

120. In the bath curve model, which one of the sections represents the period when catastrophic failure

are likely to occur ?

A. Infant mortality. B. Constant failure rate period.

C. Wear out period. D. All periods.

121. Which of the following is NOT a major consideration in performing a human factors analysis ?

A. Hazard analysis. B. Conventional user expectations.

C. Latent path analysis. D. Ergonomic evaluation.

122. What is the MOST important role performed by a failure review board ?

A. To assess failures. B. To monitor corrective action.

C. To monitor reliability growth. D. To ensure that corrective action is effective.

123. Safety label construction components include which of the following ?

. An alert symbol.

. A signal-word.

. A pictorial of the hazard and consequence.

. A safety message.

A. l, ll and lll only B. ll, lll and lV only C. l, lll and lV only D. All of the above.

124. The use of PERT requires :

A. The critical path to be known in advance. B. Slack times to be added to the critical path.

C. Time estimates for each activity in the network. D. Less data than a Gantt chart.

125. The optimum cost point for total life cycle costs occurs :

A. When operations and maintenance costs are minimized.

B. When reliability program expenditures are maximized.

C. When acquisition costs plus ongoing costs are minimized.

D. When manufacturing and development costs are minimized.

126. Routine replacement of parts with a constant hazard rate will :

A. Reduce the failure rate. B. Not reduce the failure rate.

C. Increase the failure rate. D. Have an unknown effect.

127. The House of Quality (QFD) can contain which of the following components?

. Technical characteristics.

. Technical interrelationships.

. Customer/technical interfaces.

. Customer requirements.

. Technical assessments.

A. I and II only B. III, IV and V only C. II, III and IV only D. I, II, III, IV and V

128. Maintenance times on simple with straightforward repair will fit which of the following distributions ?

A. Normal. B. Exponential. C. Lognormal. D. Geometric.

129. The reliability parameter is one of the system performance parameters with significant influence on :

A. Capability. B. Transfer functions.

C. Availability and dependability. D. Hostile man-made environments.

130. From the definition of reliability it follows that in any reliability program there must be :

. A quantification of reliability in terms of probability.

. A clear statement defining successful performance.

. A definition of the environment in which the equipment must operate.

. A statement of the required operating times between failures.

A. I and II only B. I and III only C. II, III and IV only D. I, II, III and IV

131. An air handling system has a MTBF of 8000 hours, MTBMct of 120 hours, and MMT (mean

maintenance action time) of 230 hours. Determine the potential availability.

A. 0.9866. B. 0.9852. C. 0.9721. D. 0.9575.

132. One equation used to estimate MTTR is :

×

In this equation, what is ?

A. The time to the first failure. B. The time to the i th failure.

C. The time to repair the i th part. D. The time to wear-out of the i th part.

133. Quality assurance tests are :

. Performed to demonstrate that hardware meets design specification requirements including mission

environments

. Conducted to verify conformance to quality requirements and to determine acceptability of hardware

. Performed on preliminary or prototype hardware to determine design and performance requirements

A. I only B. II only C. I and III only D. I, II and III

134. The proper software tool for software development projects can help reduce test time. The software

tools used to measure internal test coverage are called.

A. Test verifiers. B. Assertion processors.

C. Test harnesses. D. Static analyzer.

135. Which answer mathematically expresses the reliability of an active parallel system in which all

component reliabilities are unequal?

A. Rs = RaRbRc - (RaRb + RbRc + RaRc) + (Ra + Rb + Rc)

B. Rs = [RaRbRc] / [Ra + Rb + Rc]

C. Rs = Ra + Rb + Rc - RaRbRc

D. Rs = [RaRbRc + RaRb + RbRc + RaRc ] / [Ra + Rb + Rc]

136. System effectiveness :

. Is a measure of the extent to which a system may be expected to achieve a set of specific mission

requirements.

. Can often be expressed as a function of availability, dependability, and capability.

. Provides a decision criterion for system selection and justification.

A. I, II and III B. I and II only C. I and III only D. I only

137. During burn-in, electronic parts would normally exhibit:

A. A log-normal failure rate. B. A constant hazard rate.

C. An increasing hazard rate. D. A decreasing hazard rate.

138. According to the Reliability Analysis Center, which of the following design objectives is NOT

supported by reliability and maintainability contributing tasks?

A. Understand the impacts on design performance.

B. Determine the feasibility of consistent product manufacture.

C. Use of proper parts and correct application.

D. Design validation.

139. Corrective maintenance is BEST defined as :

. Maintenance performed on a routine basis.

. Maintenance performed as a result of failure or out of tolerance condition.

. Advance action to forestall failure.

A. lll only B. ll only C. l and ll only D. l, ll and lll

140. A mature design is one that has been evaluated and verified to meet requirements. Which of the

following is the MOST effective method to obtain reliability growth and design maturity ?

A. Via a structured test, analyze and fix program. B. Via a simulated mission environment.

C. Via use of high reliability rated parts. D. Via use of Duane Growth Model.

141. QFD stands for :

A. Quality Function Deployment. B. Quality Failure Determination.

C. Quality Future Development. D. Quality For Development.

142. The flat portion of the bathtub curve is a region of chance failures; therefore, for the reliability

equation shown below :

A. Does not apply to this region. B. Applies to the entire bathtub curve.

C. Applies to the wear out region as well as the flat region. D. Applies only to this region.

143. Reliability safety would be considered which of the following ?

. A completely automated process.

. The absence of unacceptable hazards.

. Compliance with government regulations.

A. II only B. III only C. I and II only D. I, II and III

144. Product residual safety risk includes which two of the following ?

. The risk left over after the risk reducing plan is implemented.

. The risk associated with the selected part.

. The risk associated with a safety device.

. The risk the user introduces when they modify a product.

A. I and III only B. II and III only C. II and IV only D. III and IV only

145. 15 rocket booster engines were tested for a total of 5 hours. Three engines failed. What is the

two-sided confidence interval for MTBF using 95% confidence ?

A. 0.57, 8.06 B. 0.69, 8.06 C. 0.75, 9.20 D. 0.80, 9.50

146. Preventive maintenance is defined as :

A. Actions performed as a result of failure.

B. Repair of an item to a specified condition.

C. Actions performed on scheduled or routine basis to retain specified condition.

D. Maintenance performed for detection and preventive of incipient failure.

147. Availability can be defined as :

. A percentage.

. Related to operating time.

. Operable at the start of a mission.

A. III only B. I only C. I and II only D.I, II and III

148. Which of the following is the most valuable in Human Engineering ?

A. FMECA B. Monte-Carlo analysis C. ANOVA D. Full scale model

149. For complex electronic systems, the major contributor to repair time is generally :

A. Diagnosis. B. Disassembly/reassembly. C. Remove/replace. D. Final checkout.

150. The 80% lower confidence limit requirement for a certain go/no-go device is 0.997. How many such

devices need to be tested without any failures to meet this requirement ?

A. 392 B. 460 C. 536 D. 629

Solutions :

1 A 16 C 31 B 46 D 61 A 76 B 91 C 106 D 121 C 136 A

2 A 17 D 32 C 47 A 62 A 77 D 92 D 107 D 122 D 137 D

3 B 18 C 33 A 48 D 63 B 78 D 93 C 108 D 123 D 138 B

4 C 19 B 34 C 49 A 64 C 79 C 94 A 109 C 124 C 139 B

5 C 20 B 35 A 50 C 65 D 80 D 95 B 110 A 125 C 140 A

6 D 21 D 36 D 51 A 66 B 81 A 96 B 111 B 126 B 141 A

7 B 22 C 37 A 52 B 67 D 82 D 97 B 112 B 127 D 142 D

8 D 23 B 38 D 53 C 68 A 83 D 98 D 113 A 128 A 143 A

9 B 24 A 39 D 54 C 69 D 84 A 99 C 114 D 129 C 144 A

10 C 25 B 40 C 55 A 70 D 85 D 100 D 115 C 130 D 145 A

11 C 26 C 41 C 56 C 71 C 86 B 101 A 116 A 131 B 146 C

12 A 27 D 42 C 57 C 72 C 87 B 102 C 117 C 132 C 147 D

13 D 28 D 43 B 58 A 73 C 88 A 103 C 118 B 133 B 148 D

14 A 29 A 44 A 59 D 74 D 89 C 104 A 119 C 134 A 149 A

15 C 30 A 45 C 60 C 75 A 90 C 105 B 120 D 135 A 150 C