The Unsung Hero of the Modern World:
The Inherent Necessity of Reliability Testing and Quality Control In All
Technologies
Abstract: Technology and engineering dominate our world. Yet, as many understand,
technology is the greatest thing, until it stops working. To understand this phenomenon,
quality control and assurance is paramount; yet the importance of such reliability is not
understood or appreciated by the general public. To elucidate the extent to which
engineering design is used in product design, two opposite examples, a soda can,
representing the simplest of technology, and an aircraft, the pinnacle of aeronautics, are
used.
Key Words: Quality, Reliability, Testing, Engineering, Airplanes, Can
Prepared by: Meen Chan Seo
Submitted: 5/3/2013
WRIT-340
Section #: 66818
Meen Chan Seo is an undergraduate at the University of Southern California studying
Chemical Engineering, with an emphasis in Nanotechnology. He has focused his studies on
the field of bionanophysics, working to improve the current models of transport
phenomena on the nanoscale.
Prepared for: Illumin Magazine
The “Behind-the-Scenes”
Engineering is about solving problems. One problem that any and every manufacturing
process will run into is reliability. Though taken for granted, the reliability that we, as
consumers, have come to expect is often the final result of a long and complicated beauteous
matrimony of material science and product design that can be applied to the simplest, most
commonplace of products, such as the standard aluminum beverage can, or even to a modern feat
of engineering, a jet plane. Yet, the general public does not know about the “behind-the-doors”
aspect of product design, the quality control and assurance, despite how relevant such testing is
in everyday life for the general public, who utilizes millions of products, that, had they not gone
through stringent testing, could potentially be incredibly dangerous. It is hard to overstate the
importance of reliability in our daily lives.
The Simple
Indeed, one archetype of a product engineered with both elegant design and careful
selection of materials is the beverage can in its current form. The can industry produces one can
for each American every day, for a grand total of over one hundred billion cans per year [1]. Yet,
each of these cans are made with a level of precision and tolerance that make it so that such a
beverage container can take up to 90 pounds per square inch of pressure, which is three times the
pressure that a beverage actually exerts at the point of canning, according to the Coca-Cola
Company [2].
Such reliability begins on paper. Designed from the bottom up to be durable yet
disposable, the modern aluminum can sports several clever design features that make the can
strong enough to handle the internal pressure of the beverage itself, yet weak enough for a child
to open. It must also be environmentally friendly and cheap, so that the container can then be
discarded immediately.
One of the major problems that the soda can industry faced before 19752 was that of the
opening mechanism of the can, also known as the tab. The earliest, mass-produced rendition of
the opening mechanism for the can was known as the churchkey, referring to the additional tool
required to open the can. The churchkey acted as a crude version of the modern can opener,
containing a sharp end that would be used to puncture the tab, or in this case, a purposefully
weakened area on the can, thereby opening it. This, of course, had its problems. First, and
foremost, there was the issue of safety. Using enough force to stab open a metal can is not
exactly the epitome of carefulness. Additionally, who would expect the average consumer to
carry around such a tool on the off chance that he or she might consume a beverage from a can?
And so, the next iteration of the tab was the pull-tab, which still exists in certain types of
cans, mainly those containing soup, or dog food. This was the unrefined version of the modern
tab that many adults are familiar with today. In this mechanism, the tab, similar to the tab of
today, would be lifted, bending a small portion of the top of the can inwards. Then, the tab would
be pulled, peeling away the top and exposing a hole through which the contents would be
emptied. This mechanism, too, had its fair share of problems. First, in order to apply the
necessary force to initially puncture and depress the lid of the can, the tab had to significantly
larger than the tabs of today. Additionally, the peeled tab became an environmental problem,
creating sharp and dangerous litter that could cut and tear at both humans and animals [3].
The current variation of the tab is a work of marvel, exhibiting the synergy of engineering
and elegance. As can be seen in figure 1, the tab starts as a second class lever, where the load of
the tab is in the center, at the rivet, which is pulling down the tab. The tab is using the scored
metal section, or the opening of the can, as a fulcrum. A common example of a second class
lever is the wheelbarrow. By lifting one end of the tab, the rivet, which represents the load, is
lifted. The pressure of the can pushing upwards on the metal disk forces the can to vent excess
pressure as the rivet is lifted, resulting in the initial hissing noise that consumers have become
accustomed to hearing.
Then, the tab results in the more commonly known first class lever, where the rivet acts
as the fulcrum at the center of the tab, like a seesaw. The two opposing forces, both trying to
push upwards, are the reduced pressure from trying to push up the scored metal section, and the
force generated by lifting the end of the
tab. When the force lifting the tab is
strong enough, then the scored metal
section will depress and creates the
popping noise of the can opening. The
can will then be ready for consumption
[4].
Figure 1. (a) The tab acts like a wheelbarrow, a second class lever, with the rivet at the
center pulling downward, and the tip of the tab acting as the turning point, or the fulcrum.
(b) As the force pulling the tab gets greater, the fulcrum and the load switch places,
resulting in a seesaw-like first class lever.
The general public does not recognize the genius that is the can tab, despite the level of
effort that went into developing it. Before the general usage aluminum can was included in our
daily lives, an additional tool analogous to the bottle opener was required to drink even soft
beverages. Using engineering, product developer attempted to simplify this and remove the
churchkey tool, but to this end introduced a level of litter that is unacceptable. Through timeless
improvements, this product, the aluminum can, was made vitually flawless. However, these
multitudes of problems solved by the new tab, though significant, are not recognized anymore;
the populace has come to expect such fine-tuning in the products of their daily lives, taking the
engineering for granted.
The Complex
Many may think that, though a beverage aluminum can is indeed a reliable and welldesigned product, a can is just a can. However, this level of attention to detail must be given to
all products, simple or complex. A can, though an exhibition of the elegance in simplicity, does
not show the whole picture.
An airplane, on the other hand, is an exhibition of the elegance in complexity and true
engineering. A man-made machine fulfilling man’s dreams of flight, the airplane has impacted
both our world and our imaginations. The current Federal Aviation Administration (FAA)
standard for airplane reliability is possibly one of the most stringent in our world. Aside from the
obvious intent of protecting the lives of those who utilize this mechanized wonder, understanding
the process of quality control and assurance in a machine with over a million separate parts and
over thirty miles of electrical wiring helps the manufacturer advance the technology from the
inside out [5]. Similar to the development of the aluminum beverage can, the airplane began as a
concept riddled with flaws in terms of usability and safety, but went through the process of
quality control and reliability to the point of becoming a multibillion dollar industry and what is
essentially the safest form of commercial travel available.
The process is extremely complex. Some components of the plane age with respect to
their usage cycles, which, in this case, is one set of takeoff and landing. For example, the
fuselage, or the main body, receives material fatigue only during the depressurization and
repressurization; the actual time spent in either state has virtually no effect on its lifetime. Other
components, such as the engines or pumps, which actively work during the actual flight, will
fatigue as a function of flight hours. In addition, components that are susceptible to corrosion of
any kind, such as chemical decay or rust, will fatigue as a function of actual calendar time.
Finally, some components, the wing flaps being a prime example, experience fatigue and decay
as a function of all three measures of time, flight cycles, flight time, and calendar time [6].
As with a car, satellite, computers, or any other complicated product, an airplane is
designed with a specific lifetime. The manufacturer predicts both the typical and atypical usage
of the plane. Using models for corrosion, fatigue, oxidative and galvanic reactions, and other
phenomena, the manufacturer can then predict the lifetime of each individual component. The
interesting point of airplane testing, and the main point of difference between these flying
machines and, for example, the land-locked automobile, is the FAA’s requirement of all
airplanes to undergo a process that is known as Maintenance Steering Group #3, or MSG3.
MSG3 is the commercial inspection process creation standard [7].
The point of the MSG3 is to ascertain exactly how long an airplane can be flown safely
and to determine maintenance protocols. In order to properly establish the risk during each flight,
the FAA has determined that the manufacturer of the plane in question must provide substantial
proof of testing the plane beyond twice the desired level of usage [6]. As an example, a fuselage
tested for 10,000 flight cycles is safe for use up to 5,000 times in a commercial setting. One
interesting point of note is that, by this rule, the FAA does not care about the actual durability of
the planes that manufacturers produce. The only point of testing that the FAA truly looks for is
reliability. If the manufacturer were to state that a newly designed plane was safe for a mere ten
flights, each spanning three hours, then if the manufacturer could prove beyond statistical doubt
that each plane was safe to fly for exactly twenty flights, each lasting six hours, then the FAA
would allow this specific plane to enter the industry.
Interestingly, the FAA’s definition of a “fail-safe damage tolerant airplane” includes
having regular maintenance [8]. The protocol of maintenance developed by the MSG3 is
extremely detailed, because of the extensive amounts of testing on new designs required by the
FAA. In addition to having to understand the structural and material aspects of the different
designs of aeronautics in the industry, maintenance inspectors know for each plane where and
when each aging phenomena will occur, how often it must be looked for, and how dangerous
each fault is. In effecting these protocols, not only were the hard, physical, material sciences
employed, but also factors such as the probability of a human inspector actually observing said
faults vis a vis the protocol, the type and magnitude of lighting used in typical hangers, and the
equipment and technical knowledge available for use by the maintenance inspection agency [9].
But, as always, all this technical protocol is ignored and taken for granted by the average
consumer until some part is shown to be wrong, often with deadly results. One example is the
Aloha Incident of 1988, where a Boeing 737 suffered what is described as explosive
decompression of the fuselage resulting in one death and 65 injuries. The National
Transportation Safety Board, upon further review, found issues with “the quality of air carrier
maintenance programs, the FAA surveillance of those programs, the engineering design,
certification, and continuing airworthiness of the B-737… and the human factor aspects of air
carrier maintenance and the inspection for the continuing airworthiness of transport category
airplanes, to repair procedures an the training, certification, and qualification of mechanics and
inspectors [10].” Ultimately, such an accident proves how such reliability in our products, simple
or complex, can be of paramount importance.
The Unspoken Hero
Airplanes are representative of many a pinnacle of mankind. The creation of the airplane
represented the dreams of the Wright brothers, and, indeed, all of humanity: the desire to soar the
skies. They are also representative of the pinnacle of mathematics and engineering, as
aeronautics took a hold of the 20th century, ushering the advent of the Space Age. The rise of
commercial flight allowed for industrial expansion. But all of this is only possible through the
acknowledgement of producers, guaranteeing effectiveness, functionality, and safety. This
process is universal to every product. The consumer demands reliability, without even realizing
it. There are satisfaction guarantees, exchange and return policies, and a hotline for complaints
and concerns. The entire material world, from the simplest idea to one representing the dream of
man, is based off this implicit agreement of reliability between the consumers and the producers.
To this end, product design engineers think of the entire standard and potential usage of a
product, and the many ways the product can fail. As a soda tab may break off prematurely, the
product may fail to deliver the result necessary. At the same time, even if the product worked
perfectly, unintended side effects, such as the resulting mounds of sharp tabs littering the sandy
beaches, may arise. Ultimately, product design is an extremely complicated process that is the
backbone of many industries. Though the backstage work may be unknown to the consumers,
reliability would be noticed only when it is not there.
Works Cited and Referenced
[1] J. L. Duncan. "The Aluminum Beverage Can." Scientific American, pp. 48-53, Sept. 1994.
[2] S. Meraj (2000). Pressure in a Can of Soda [Online]. Available: http://www.hypertext.com
[3] T. Vanderbilt (2012, September). The Brilliant Redeisng of the Soda Can Tab [Online].
Available: http://www.slate.com
[4] B. Hammack. Pop Can Stay-On Tab [Online]. Available: http://www.engineerguy.com
[5] C. Addams, S. Angers (2003, April 15). A World of Service for the Boeing 737 [Online].
Available: http://www.boeing.com
[6] D. O. Tipps et al., “Statistical Loads Data for the Boeing 777-200ER Aircraft in Commercial
Operations,” University of Dayton Research Inst., Dayton, OH, Rep. UDR-TR-2005-00106,
Nov. 2006.
[7] C. Adams. (2009, July 1). Understanding MSG-3 [Online]. Available: http://www.aviationtoday.com
[8] A. Ushakov, et al., “Probabilistic Design of Damage Tolerant Composite Aircraft Structures.”
Central Aerohydrodynamic Inst., Zukowski, Rep. DOT-FAA-AR01-55 Russia, Jan. 2002.
[9] J.P. Gallagher et al., “The Pivotal Role and Current Status of Nondestructive Inspection Systems
in the Maintenance of Aging Aircraft,” in RTO AVT Specialists’ Meeting, Manchester, UK,
2001. doi: [ADP014078]
[10] (1988,
April 28). Aloha Airlines, Flight 243, Boeing 737-200, n73711 [Online]. Available:
http://www.ntsb.gov