Reliability engineering chapter-3 failure data collection and analysis

Chapter-3 Failure Data Collection and Analysis
Introduction
• Failure data are the backbone of reliability studies because
they provide invaluable information to concerned
professionals such as reliability engineers, design engineers,
and managers. In fact, the failure data of a product are the
final proof of reliability related efforts expended during its
design and manufacture.
• It would be impossible to have an effective reliability program
without the collection, analysis, and use of information
acquired through the testing and operation of products used in
industrial, military, and consumer sectors.
1

• The main purpose of developing a formal system of collecting,
analyzing, and retrieving information acquired from past
experiences is to allow design and development of better and
more reliable products without repeating the previous efforts
concerning research, design, and testing to achieve the current
product reliability.
• Thus, the fundamental goal of a failure data collection and
analysis system is to convert the relevant information
accumulated in various sources into an effectively organized
form so that it can efficiently be used by individuals with
confidence in conducting their assigned reliability related
tasks.
2

In particular, the nature of the products and their intended
applications are important factors in deciding the extensiveness,
form, etc. of a failure data collection and analysis system. For
example, a company stamping out stainless steel flatware will
require a simple data system as opposed to a complex data
system for a company manufacturing aircraft.
All in all, prior to deciding the size, type, etc. of a failure data
system, consider factors such as individuals requiring
information, information required by the individuals to meet
their needs, and frequency of their need.
3

• Failure data uses: There are many areas for the uses of failure
data including conceptual design, preliminary design, test
planning, design reviews, manufacturing, quality assurance and
inspection planning, logistic support planning inventory
management, procurement, top management budgeting, and
field service planning.
• Nonetheless, some of the more specific uses of failure data are
estimating hazard rate of an item, performing life cycle cost
studies, making decisions regarding introduction of redundancy,
predicting an item's reliability/availability, performing
equipment replacement studies, recommending design changes
for improving the product’s reliability, performing cost vs.
reliability studies, determining the maintenance needs of a new
item, and conducting preventive maintenance studies.
4

Failure Data Collection Sources in Equipment Life Cycle and Quality
Control Data
There are many sources of collecting failure related data during an
equipment life cycle. Eight of these sources are as follows:
1. Warranty claims
2. Previous experience with similar or identical equipment
3. Repair facility records
4. Factory acceptance testing
5. Records generated during the development phase
6. Customers’ failure reporting systems
7. Tests: field demonstration, environmental qualification, and field
installation
8. Inspection records generated by quality control/manufacturing
groups
In order to maintain the required quality standards, the quality control
groups within organizations regularly perform tests/inspections on
products/equipment.
The important components of the quality control data are incoming
inspection and test results, quality audit records and final test results,
in-process quality control data, results of machine and process
5
capability studies, and calibration records of measuring instruments.

FAILURE REPORTING AND DOCUMENTATION SYSTEM DESIGN
GUIDELINES AND FAILURE DATA COLLECTION FORMS
• A failure reporting and documentation system could be very effective
if a careful consideration is given during its design. Some of the
associated design guidelines are simplicity and clarity of the failure
reporting form, effective and efficient documentation of the
information on failures.
• The backbone of a failure data system is the failure data collection
form. Such forms must be designed so that they require minimum
effort to collect failure data and provide maximum benefits. Also,
these forms must be tailored to meet the requirements of a specific
organization or program effectively.
• Usually such forms are generally designed to include information such
as form number, item description, location of the hardware, serial
number of the failed item and manufacturer’s name, description of
the failure, form completion date, dates on which failure occurred,
was detected and corrected, operating hours from the previous
failure, time taken for repair, repair cost, serial number and
manufacturer of the replaced part, repair-person's name and
appropriate signatures.
• Table 1 presents useful standard documents for failure data collection.
6

Table 1: Selective standard documents for failure data
collection
7

External Failure Data Sources
There are a large number of organizations, data banks, and documents
to obtain failure data related information. Some of these are as
follows:
ORGANIZATIONS
• Government Industry Data Exchange Program (GIDEP). It is probably the
most comprehensive source for obtaining data and is operated and funded by
the U.S. government. A company must formally become a full or partial
participating member of the GIDEP before making use of it. This means that
the company must also submit its own data to GIDEP in order to receive data
from it. The system is managed by the GIDEP Operations Center. Fleet Missile
Systems, Analysis and Evaluation Group, Department of Defense, Corona,
California 91720.
• National Technical Information Service (NTIS). This is also a good source for
obtaining various types of failure data and the service is managed by the U.S.
Department of Commerce. The address of the NTIS is 5285 Port Royal Road,
Springfield, Virginia 22161.
• Reliability Analysis Center (RAC). RAC provides various types of information
concerning reliability and is managed by the U.S. Air Force (USAF). In
particular, the on electronic Parts Reliability Data (NPRD) reports are released
periodically by the center. The address of the RAC is Rome Air Development
Center (RADe), Griffiss Air Force Base, Department of Defense, Rome, New
York 13441. 8

• Defense Technical Information Center. This center is a useful source
for obtaining various types of failure data related information,
particularly concerning the defense equipment. The address of the
center is Defense Logistics Agency, Cameron Station, Alexandria,
Virginia 22314.
• Parts Reliability Information Center (PRINCE). This center is quite
useful to obtain various types of data related to space systems. The
address of the center is Reliability Office, George C. Marshall Space
Flight Center, National Aeronautics and Space Administration (
IASA), Huntsville. Alabama 35812.
• Institute of Electrical and Electronics Engineers (IEEE). This is the
largest professional body in the world and provides failure data
concerning various electrical related items. The address of this
organization is 345 East 47th Street, New York, New York 10017.
• National Electric Reliability Council (NERC). NERC publishes various
types of failure data collected annually from the U.S. power plants.
This organization is located in New York City.
• Insurance Information Institute (III). This organization provides data
on disaster impacts and related matters. III is located at 110 William
Street, New York, New York 10017.
9

DATA BANKS
• Nuclear Plant Reliability Data System (NPRDS). This system
provides various types of failure data on equipment used in
nuclear power generation. NPRDS is managed by the South
West Research Institute, San Antonio, Texas.
• Equipment Reliability Information System (ERIS). This system
provides failure data on equipment used in electric power
generation. The system is managed by the Canadian Electrical
Association (CEA), Montreal, Quebec.
• SYREL: Reliability Data Bank. This data bank provides failure
data Oil equipment used in power generation. The data bank
is managed by the Systems Reliability Service, Safety and
Reliability Directorate, United Kingdom Atomic Energy
Authority (UKAEA), Wigshaw Lane, Culcheth, Warrington,
Lancashire WA3 4NE, England.
• ESA Electronic Component Data Bank. This data bank provides
data on various types of electronic parts, especially used in
space environment. Its address is Space Documentation
Service, European Space Agency (ESA), Via Galileo, 00044
Frascati, Italy. 10

DOCUMENTS
• MIL-HDBK-217, Reliability Prediction of Electronic Equipment, Department
of Defense, Washington, D.C.
• Component Parts Failure Data Compendium, Engineering Dept., Electronic
Industries Association, IIW. 42nd St., New York, New York 10036.
• RADC-TR-85-194, RADC Non-electronic Reliability Notebook, Reliability
Analysis Center, Rome Air Development Center (RADC), Griffiss Air Force
Base, Rome, New York 13441-5700, 1985.
• IEEE-STD-500-1977, IEEE Nuclear Reliability Data Manual, John Wiley &
Sons, New York, 1977.
• WASH-1400 (NUREG 75/014), Appendix 3 and 4, Reactor Safety Study: An
Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants,
U.S. Nuclear Regulatory Commission, Washington, D.C., 1975.
• Dhillon, B.S., Mechanical Reliability: Theory, Models, and Applications,
American Institute of Aeronautics and Astronautics, Washington, D.C.,
1988 (Chapter 9 contains failure data on various mechanical parts).
• RAC EMD 1 and 2, Electronic Equipment Reliability Data, Reliability
Analysis Center (RAC), Rome Air Development Center, Griffiss Air Force
Base, Rome, New York.
• NUREG/CR-1278, Handbook of Human Reliability Analysis with Emphasis
on nuclear Power Plant Applications, U.S. Nuclear Regulatory Commission,
Washington, D.C.
11

Failure Data for Selective Items and Tasks
• For many decades, failure data on engineering items and
various tasks performed by humans have been collected and
analyzed. In order to demonstrate the type of analyzed and
available failure data, Tables 1 and 2 present failure rates for
some selected electronic and mechanical items, respectively,
and Table 3 contains human error data for a few selective
tasks.
12

Table 2: Failure rates for some electronic items.
13

Table 3: Failure rates for some mechanical items.
14

Table 4: Human error rates for some tasks.
15

16
Weibull Distribution and Parameters of Weibull distribution.
The Weibull Distribution
This continuous random variable distribution is named after W.
Weibull, a Swedish mechanical engineering professor. This
distribution takes account of a non-constant hazard function. The
Survival function is given by:


 



 



t
R(t) e
where β is the shape parameter and η is the scale parameter or characteristic life.
The characteristic life is the life at which 63.2% of the population will have failed.
When β = 1, the hazard function is constant and therefore the data can be
modeled by an exponential distribution with η=1/λ .
When β<1, we get a decreasing hazard function and
When β>1, we get a increasing hazard function
Figure 7, below, shows the Weibull shape parameters superimposed on the bath-tub
curve. This distribution used to describe experimentally observed variation in
the fatigue resistance of steel, its elastic limits etc.

17
Figure 7 bath tub curve and the weibull distribution

Reliability engineering chapter-3 failure data collection and analysis

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