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Reliability Engineer

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Reliability Engineer Certification

Study Guide

Test your preparedness for the exam using this study guide. Answers are at the end.

  1. Which of the following is best defined as the practice of using parallel components and subsystems?
    1. Maintainability
    2. Reliability
    3. Optimization
    4. Redundancy

  2. Balancing a reliability requirement against other design parameters, such as performance, cost, or schedule, and then analyzing the consequences of placing special emphasis on one of these factors is called
    1. reliability allocation
    2. reliability predictions
    3. trade-off decisions
    4. system modeling

  3. Software reliability planning includes all of the following EXCEPT
    1. selecting models for data analysis and prediction
    2. modeling acquisition of computer software systems
    3. trade-offs of general purpose programs vs. commercially available programs
    4. trade-offs involving cost, schedule, and failure intensity of software products

  4. The lifetime of a mechanical lifter is normally distributed with a mean of 100 hours and a standard deviation of 3 hours. What is the reliability of the lifter at 106 hours?
    1. 0.0228
    2. 0.0570
    3. 0.9430
    4. 0.9772

  5. In an analysis of variance, which of the following distributions is the basis for determining whether the variance estimates are all from the same population?
    1. Chi square
    2. Student's t
    3. Normal
    4. F

  6. A full factorial design of experiments has four factors. The first factor has two levels, the second factor has three levels, the third factor has two levels, and the final factor has four levels. How many runs are are required for this analysis?
    1. 16
    2. 48
    3. 192
    4. 256

  7. In a certain application, two identical transducers are used to measure the vacuum in a system. The system is considered to have failed if either of the vacuums read by the transducers varies from the standard by more than 10 mm Hg. Which of the following is the correct reliability logic block diagram for the transducer assembly?


  8. Assuming perfect switching and perfect starting, which of the following systems has the longest mean life if each system consisits of n units with identical reliability?
    1. A series system
    2. A parallel system
    3. A k out of n system
    4. A cold standby system

Questions 9-11 refer to the following situation:
A high incidence of failures has developed during aircraft acceptance testing. The identified failure is that an instrument panel light has malfunctioned on 6 of the last 10 aircraft tested. This problem needs to be investigated and a Failure Reporting and Corrective Action System (FRACAS) needs to be completed without stopping aircraft production.

  1. The first step of the investigation should be to
    1. collect additional data on similar events over the last two years
    2. conduct failure analysis to determine the failure mode and mechanism
    3. conduct surveillance testing on suspect components
    4. establish a cross-functional team to brainstorm on the cause and effect

  2. If the cause of the failure is determined to be a faulty subassembly manufactured only by a single supplier, and this situation is threatening to shut down aircraft production, the next step should be to
    1. visit the supplier to assist in determining the root cause of the problem
    2. initiate a supplier corrective action and return all of the unsorted inventory
    3. issue a Government and Industry Data Exchange Program (GIDEP) alert
    4. update the inspection instruction and retrain receiving inspection

  3. If a corrective action notice was sent to the supplier of a faulty subassembly and the supplier's response states that the root cause is simply an operation error, the next step should be to
    1. accept the response and close the FRACAS
    2. visit the supplier to develop a better understanding of the root cause
    3. issue a Government and Industry Data Exchange Program (GIDEP) alert
    4. begin looking for a new supplier

  4. Which of the following is an appropriate use for experimental design?
    1. Establishing product requirements
    2. Developing a fault-tree analysis
    3. Ensuring the robust design of a product
    4. Analyzing customer complaint reports

  5. Which of the following is NOT considered good practice in reliability design?
    1. Using proven parts
    2. Using series design
    3. Using failure mode and effects analysis (FMEA)
    4. Simplifying item configuration

  6. According to Taguchi, robustly designed experiments should employ all of the following techniques EXCEPT
    1. inner and outer arrays
    2. signal-to-noise ratios
    3. linear graphs
    4. fold-over capabilities

  7. Which of the following measures can be used to find a quick approximation of the availability of a system?
    1. Mean time to failure (MTTF) and mean time to repair (MTTR)
    2. Failure rate and failure mode
    3. Mission time and failure rate
    4. Downtime and time to repair

  8. The investment in automated test equipment is often justified under which of the following circumstances
    1. Numerous tests must be performed.
    2. Repair times must be short.
    3. Conformance records are required.
    4. Traceable records are required.

  9. For a company operating multiple units of production equipment, the observed failure rate is 42 x 10-6 failures per operating hour, and the preventive maintenance rate is 320 x 10-6 actions per hour. What is the mean time between corrective and preventive maintenance (MTBM)?
    1. 2,688.2 hr
    2. 2,762.4 hr
    3. 2,840.9 hr
    4. 26,935.0 hr

  10. All of the following are purposes of a production reliability assurance test (PRAT) EXCEPT to
    1. detect significant shifts between the as-built reliability and the as-designed reliability
    2. assess performance against reliability requirements
    3. assess actual product reliability against reliability requirements
    4. minimize the need for specific process controls

  11. The primary aim of sequential-life testing is to determine
    1. the probability density function of failures
    2. the mean time between failures (MTBF)
    3. whether the stress-level variation is significant
    4. whether a lot meets the reliability goal

  12. A small sample from a product population is subjected to multiple levels of elevated stress. Which of the following could be used to model the life of the product?
    1. Poisson process
    2. Pascal expansion
    3. Pareto rule
    4. Inverse power law

  13. Which of the following are important elements in the concept of consumer risk?
    1. Frequency
    2. Schedule
    3. Damage
      1. I and II only
      2. I and III only
      3. II and III only
      4. I, II, and III

  14. Which of the following tools is used to analyze the safety of a system?
    1. Fault-tree analysis
    2. Failure reporting and corrective action system
    3. Reliability allocation
    4. Environmental stress screening

  15. A component fails on the average of once every 4 years with 75% of the failures observed to occur during stormy weather. If there are 12 hours of stormy weather to every 240 hours of good weather, what are the failure rates for stormy and good weather, respectively?

    16.   

  16. A go/no-go device is tested until it fails. If X is the number of tests to first failure with no wear out present, and the probability of success on each test is .99, then the probability that X is greater than 5 is:
    1. 0.9310
    2. 0.9410
    3. 0.9510
    4. 0.9610

  17. Given a reliability growth test in progress having accumulated 4 failures during 5000 test hours. Assume a growth rate of 0.3, what is the expected MTBF at 25,000 hours?
    1. 1250 hrs
    2. 1895 hrs
    3. 2026 hrs
    4. 3856 hrs

  18. A Weibull distribution has been found to describe the reliability distribution with characteristic life = 12,000 hours, and shape parameter If these are good parameters, at what time will reliability decrease to .85?
    1. 2204 hrs
    2. 3503 hrs
    3. 4838 hrs
    4. 5254 hrs

Answers:
1. d 6. b 11. b 16. b 21. a 26. d
2. c 7. a 12. c 17. b 22. a  
3. b 8. d 13. b 18. d 23. a
4. a 9. b 14. d 19. d 24. c
5. d 10. b 15. a 20. d 25. c

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