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Engineers Dilemmas When Forced to Proceed with Defective Design
Engineers are the professionals who make things work. They create products and design the processes that make the products. They also prevent environmental damage and fix the problems that may arise from pollutions and natural disasters. In short, they are the people who make living more convenient and who make possible technological fantasies.
However, while engineers may strive to reduce the hazards brought about by the application of new technologies, they are not always successful. Very often, it is not the technological barriers that they cannot overcome, but rather the obstacles placed by fellow human beings.
Major engineering projects in aeronautical and aerospace applications are normally very costly and time sensitive. Correcting a design defect can be very costly and time consuming. Economic cost consideration may not always permit major redesigning to be performed. In order to better appreciate the dilemmas faced by engineers when they are faced with design faults, we shall discuss two well-known cases. The first case is involving the Challenger Space Shuttle and the second case involves the DC-10 Jumbo Jet.
The Challenger Space Shuttle Case
For a better appreciate of the complexity of this case, some background information is in order.
The main vehicle in the space shuttle is the orbiter. It is powered by three rocket engines. The orbiter contains a huge cargo bay fro carrying payload such as the space lab or satellite that will be launched from the space shuttle. The rockets in the orbiters use liquid hydrogen fuel. The major portion of the hydrogen is stored in a big external tank. The oxygen needed to support fast combustion of the hydrogen fuel in the rocket engines is also stored in the external tank. Once the hydrogen and oxygen in the external storage tank are used up, the tank is jettisoned (after about eight and a half minutes from lift-off).
The rockets in orbiter alone do not provide sufficient power to send the shuttle into space because of the huge weight. The additional thrust during lift-off is provided by two external solid rocket boosters. Since the booster rockets are huge and long, they are manufactured in segments and the 5 segments are joined together at the launch site. These joints are called field joints since they are put together at the launch site. The field joints are not as sturdy as those performed in the factory and the sealing is also not as reliable. The lower performance of these field joints was apparent from the various tests. Of particular was the concern that the sealing at the joint to prevent the hot rocket air from leaking at low temperature. However, the redesigning process was slow and no new design was available.
The most significant event took place on the night of Jan 27, 1986. The Challenger space shuttle was to be launched in the morning. The maker of the solid rockets boosters, Morton-Thiokol, held a teleconference with NASA managers. The engineers at Morton-Thiokol presented their concerns about the safety of the launch. In particular, the danger due to the poor performance of the field joints under the influence of the cold weather. They recommended that the launch be postponed till the temperature rose to a more suitable level.
The NASA managers were not happy with the recommendation. There were several reasons. Apparently, they believed the solid rocket boosters would be able to perform well although the temperature was expected to be low - about 26 degrees Fahrenheit. This was because in their design specifications, the solid rocket boosters were supposed to be able to perform safely at temperature as low as 31 degrees Fahrenheit. However, it was suspected that the NASA managers were keen to launch the space shuttle without any further delay because of the following three reasons:
Reason 1: Political Pressure
President Reagan was to speak on education during his State of the Union Address while the space was to be in space. It would be a very opportune time with a teacher in space at that time.
Reason 2: Economic Pressure
NASA wanted to make the space shuttle program commercially attractive. At that time, the European Space Agency was posing too much of a competition
Reason 3: Scheduling Backlog
There had been too many delays in the past and there is a backlog of launches. In particular, the next launch was to observe Comet Halley before the Russians.
As a result of the pressure from NASA managers, Morton-Thiokol managers changed their recommendation to launch from no-launch, even though their engineers protested strongly against it.
Challenger space shuttle was launched as scheduled the next morning and it exploded, killing all the astronauts.
The DC-10 Jumbo Jet Case
When the first fully loaded DC-10 jumbo jet exploded in 1974 over the suburbs of Paris, killing 346 people, it was not unexpected by some people who were in the know about the defective design of the air craft. In fact the engineers in Convair who perform the fuselage design for McDonnell Douglas wanted to redesign the cargo doors and to strengthen the cabin floor because there was the danger in the current design that would result in the cargo door being forced open during flight leading to the collapse of the passenger cabin floor where control cables are laid and crash result.
The top management at Convair did not inform McDonnell Douglas of the design defect because of fear of big financial cost and liabilities, as well as delay in putting the new aircraft into production.
Observations:
There are close parallels between the two cases. Both designs were known to be flawed by the engineers who tried to alert the management but the management decisions were clouded by monetary considerations which led to the eventual loss of the crafts and the lives of the occupants. In both cases, engineering hats were removed and management hats put on.
Article Source: OrganizingWeb.net
About the Author
Jacob Gan PhD (Michigan) has more than 20 years of teaching experience in a university and 8 years of business/industrial experience after graduation.
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