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A Series of Unfortunate MTBF Assumptions

A Series of Unfortunate MTBF Assumptions

A Series of Unfortunate MTBF Assumptions

The calculation of MTBF results in a larger number if we make a series of MTBF assumptions. We just need more time in the operating hours and fewer failures in the count of failures.

While we really want to understand the reliability performance of field units, we often make a series of small assumptions that impact the accuracy of MTBF estimates.

Here are just a few of these MTBF assumptions that I’ve seen and in some cases nearly all of them with one team. Reliability data has useful information is we gather and treat it well.  [Read more…]

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Lack of An ERM Policy is Risky

Lack of An ERM Policy is Risky

Guest Post by John Ayers (first posted on CERM ® RISK INSIGHTS – reposted here with permission)

Lack of An ERM Policy is Risky

Background

A defense company I worked for wanted to get into the Sonobuoy business. At the time, one company dominated the market and usually received the largest share of the Navy contract.  A couple of other suppliers got the balance of the production quantity to keep it a competitive business.

My company developed a win strategy based on a ¼ scale prototype and purposely under bidding the competition. It worked. They won the largest piece of the production contract. [Read more…]

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The 2 Parameter Binomial Discrete Distribution 4 Formulas

The 2 Parameter Binomial Discrete Distribution 4 Formulas

This is part of a short series on the common life data distributions.

The Binomial distribution is discrete. This short article focuses on 4 formulas of the Binomial Distribution.

It has the essential formulas that you may find useful when answering specific questions. Knowing a distribution’s set of parameters does provide, along with the right formulas, a quick means to answer a wide range of reliability related questions. [Read more…]

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Miami Kicked My Butt

Miami Kicked My Butt

The Plan: Saturday and Sunday was skiing in Vermont with the family,  back Sunday night, everyone off to school Monday morning, then to the airport to get to Miami, Tuesday and Wed meetings down there, then fly out Wed night so I’m back to teach classes Thur and Fri here in Boston.  Easy Peesie!

Actual: Finish ski trip feel a little “strange” on flight down to Miami, slight chills.  Tuesday do meetings just barely, Tuesday night it hits like a freight train, The Flu, or Malaria, Aliens. On Wednesday the freight train had fully passed over me so it stopped and spent Wed backing up over me again. Thursday it went forward again over a pile of human jello. I’m not flying out for the clases on Thur and Fri, or anytime soon for that matter. Just getting home is my mission for the week.

[Read more…]

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Using Hierarchy In Complex System Requirements and Design

Using Hierarchy In Complex System Requirements and Design

Managing requirements for complex systems can be challenging, however, establishing a hierarchical framework of key questions (answered at each layer of the hierarchy) can be quite helpful.

While some regulatory authorities (such as the FAA) may require various layers of documentation and traceability, this article isn’t necessarily advocating a bureaucratic development process.  The process can be scaled based on the complexity of your system, your ability to model it’s (system) design performance and/or based on the amount of product development risk the organization is willing to assume. [Read more…]

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Process Capability Analysis I – Overview and Indices

Process Capability Analysis I – Overview and Indices

Introduction

How is a manufacturing process determined to be capable of producing parts that meet engineering requirements? Some, like the finish of a gear tooth are critical, while the roughness of a non-contact surface isn’t critical. The critical characteristics need to be identified and checked to determine if the process is capable.

This article defines the analysis concepts and indices.

Prototypes and Series Production

Process capability assessments (PCA) start during the product development process and continue into series production. Prototype parts are created by a variety of methods, ranging from hand-crafted parts to short term manufacturing in a production intent process under factory conditions. The methods that are closest to series production are the most realistic.

[Read more…]

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Should I Become a CRL, CMRP, or CRE?

Should I Become a CRL, CMRP, or CRE?
Education. Knowledge. Motivation.
Sitting for a professional society’s reliability certification is a common goal among engineers in our field. Is there a career benefit? I’m not sure the certification provides the benefit. I think it is the work toward certification and the application of the required knowledge that provides the benefit.

[Read more…]

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Could Delta Airlines Have Missed Some Hidden Failures?

Could Delta Airlines Have Missed Some Hidden Failures?

Yet another example of why it’s important to understand the failure modes that make your system vulnerable to complete shutdown. Delta Airlines is learning this lesson the hard way today after having to inform customers around the world that all of its flights would be on hold or even canceled due to a “system wide outage”.

Delta listed the cause for the outage as a power failure near its world-wide office location in Atlanta, Georgia while those at Georgia Power believe it was the failure of Delta’s equipment that caused the power outage.

While each company points the finger at the other, the reality is Delta’s customers around the world are sitting at airports or at home wondering when the problems will be resolved and when Delta will be able to accommodate their travel needs.

[Read more…]

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Emphasizing Product Requirements

Emphasizing Product Requirements

In this article we’ll explore the topic of requirements, and attitudes about identifying requirements before the design work begins.

In my experience, I’ve had design resources literally state “I hope there are no requirements”.  (Unconstrained design and no requirements certainly made this designer’s job much easier.)

There are several other reasons requirements are sometimes neglected:

[Read more…]

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Reputational Risk and ERM

Reputational Risk and ERM

Guest Post by James K. Kline (first posted on CERM ® RISK INSIGHTS – reposted here with permission)Reputational Risk and ERM

Introduction

It is estimated that an organization’s reputation accounts for over a quarter of its market value. As such managing reputational risk has become an important issue for C-Suite members.  This piece examines the issues surrounding reputational risk and how an Enterprise Risk Management (ERM) approach can help manage this risk.  [Read more…]

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What is Life Cycle Costing? 

What is Life Cycle Costing? 

Life cycle costing (LCC) is a way of analysing equipment purchase choices. If the analysis is done right and all factors are addressed, and the information is good, you would select the item that cost the least amount to own (buy and use) over its working life. This piece of equipment when compared to other suitable items would perform its lifetime service at least total cost to the organisation. [Read more…]

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How to Craft a Purpose-filled Mission Statement

How to Craft a Purpose-filled Mission Statement

Unlocking your Engineering Career Potential

One of the best pieces of career advice that I have ever heard is to treat your career as a company, of which you are the CEO.  And like any company, your career will need a guiding principle that will help you stay focused on your purpose.  Companies today would not think of operating without a mission statement to guide them.  However, too many of us skip this critical aspect of running our own careers. [Read more…]

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The 2 Parameter Birnbaum-Saunders Distribution 7 Formulas

The 2 Parameter Birnbaum-Saunders Distribution 7 Formulas

This is part of a short series on the common life data distributions.

The Birnbaum-Saunders distribution is a univariate continuous distribution. This short article focuses on 7 formulas of the Birnbaum-Saunders Distribution. This distribution was designed to model the Miner’s rule, thus allowing for non-constant fatigue cycles through accumulated damage.

If you want to know more about fitting a set of data to a distribution, well that is in another article.

It has the essential formulas that you may find useful when answering specific questions. Knowing a distribution’s set of parameters does provide, along with the right formulas, a quick means to answer a wide range of reliability related questions. [Read more…]