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Checklists and Testing Systems

Checklists and Testing Systems

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:ReliabilityQuality AssuranceMaintainabilitySafety

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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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