reliability engineering for maintenance

Uptime Magazine's Steve Thomas (left) recently caught up with Henry Ellmann (right) to discuss his keynote address at IMC-2012 in Bonita Springs, Florida, December 4-7th.

By Larry Tyson

Part 1 of this article appeared in the June/July 2011 issue of Uptime Magazine

This is a follow-up article to one published in the June/July 2011 issue of Uptime magazine.¹ Our component of interest was the fuel control (FC), with a failure mode (FM) of "flameout," where one of two engines shut down in flight. This is called in-flight abort (IFA) and has a direct "safety of flight" impact on aircraft and aircraft missions, as well as the crew, and, of course, is a very undesired consequence.

By Terry Nelson

In response to Brian Webster's article (Understanding & Comparing Risk), Terry Nelson requested the opportunity to supply additional information relating to his article in the Oct/Nov 2011 issue of Uptime.

By Brian Y. Webster

In the Oct/Nov11 edition of Uptime (Risk & Criticality), a concept of risk was introduced that utilized a Euclidean distance of probability and consequence, mathematically written as

Risk2 = Probability2 + Consequence2

The author claimed that "this [method] provides for accurate comparison of relative risk."¹ The purpose of this article is to explain the conflict between traditional risk calculation methods and distance methods, as well as the potential poor business decision that could result from using distance methods. For the purpose of this article, the Euclidean distance for assessing risk as described in the original article will be called the "positional risk."