Transcript Document

National Aeronautics and Space Administration
Checklists
and Testing
Systems
www.nasa.gov
Systems
 As you learned in Unit 3, systems require feedback to ensure
proper function.
 If any part of the transportation cycle is held up, the entire success
of the mission could be at risk.
 To ensure proper function of the system, engineers use checklists
throughout the mission to provide feedback.
 Checklists are created to be sure that systems are stabilized before
the next stage in the transportation cycle.
 For example, before ejecting the lunar lander from the crew vehicle,
the astronauts must complete a series of checklists to ensure that
the separation of the vehicles will be successful.
 Before launching any space vehicle, a series of checklists must be
completed successfully.
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Designing a Checklist
 Designing a checklist to ensure proper function of a system is as
complex as designing troubleshooting diagram, similar to what you
did in Unit 3.
 Checklist designers need to consider:
 Accuracy
 Clarity
 Simplicity
 Conciseness
 Correctly identifying emergency or abnormal situations.
 Involving multiple people (usually two) in accomplishment to verify critical
checklist items.
 Objective (factual and data-based, versus subjective opinions)
 Images when appropriate
 Realistic that the checklist can be completed in a certain amount of time
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Checklist Categories
Checklists should consider the
following tests to insure the safe and
proper function of a system:
Reliability
Quality Assurance
Maintainability
Safety
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Reliability
 Reliability testing
 Reliability means that the part or product will perform consistently over a
period of time and during repeated use.
 Reliability testing can be for individual parts or a subsystem or an entire
system.
 For example, if the part considered for the Ares I has been used in the past for the
exact same application, additional reliability testing is not necessary. If the same
part is going to be used for an application that varies in the slightest from the
original application, then additional testing is necessary.
Consider a toaster: What tests might you perform on a toaster to make sure it is
reliable (meaning makes perfectly toasted bread every time)?
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Quality Assurance
 Quality Assurance includes making sure that products purchased
from various vendors around the world work together correctly to
meet the specific needs of the mission and function at the desired
specifications.
 NASA has adopted the Society of Automotive Engineers Aerospace
Standard
 For example, when purchasing from a vendor, under the Terms and
Conditions in the purchase order, NASA stipulates the specific requirements
they need in terms of the type of material, size, etc.
Consider a toaster: What could you do if you were the manufacturer of the toaster
to insure quality of the product?
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Maintainability
 Maintainability consists of the tests and verification of the system
design characteristics so that the need for maintenance is
minimized and downtime is minimized when maintenance action is
necessary.
 For example, when designing Items most critical to system operation that
require rapid maintenance, they should be the most easy to access.
Consider a toaster: What would you change in the design to increase the
maintainability of the toaster?
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Safety
 Safety testing is conducted to insure systems can be operated
safely by human operators and that systems that are used do not
pose a safety risk prior to, during, and after operation.
 For example, NASA will test the ascent abort system for Orion’s Launch
Abort System in 2012 and 2013 to determine how the vehicle will perform if
the person is unable to control the vehicle in space. Obviously, without these
types of tests, the lives of the astronauts would be at risk.
Consider a toaster: What tests might you perform on a toaster to make sure it is
safe to use?
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Reflection
 Can you think of a product you currently own for which you feel the
engineers/designers did not consider reliability, quality assurance,
maintainability, or safety? What should they have considered?
 Can you think of specific examples within the NASA transportation cycle
(from the exploration presentation) where NASA might use checklists to
check for reliability, quality assurance, maintainability, and safety?
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