You may recall from Chapter 3 and the function development process called walking the dog that you’d be walking the dog again when developing failure modes. Let’s return to the fuel supply system boundary with a reminder that it has been overly simplified to suit the purposes of this book. In an actual analysis, you would gather far more detailed information about the components in the system and in the best of situations, would have fairly easy access to the actual hardware.

Figure 5-1 shows the fuel supply system boundary. In this figure, the dog’s path is depicted as a dashed line that begins at the input pump, follows the system up and through the tank, through valves and the filter, and finally through the output pump where it exits the boundary.

Figure 5-1: Fuel supply system dog walk

Begin again at the 1,000 GPM pump that receives kerosene from the upstream process. As previously mentioned, this diagram in its current state would be of little value in an actual analysis, but it does serve nicely to illustrate the concepts in this book. In order to illustrate the process of walking the dog to develop failure modes, assume that you have physical access to this system, which means the group can go outside and look at the pump, and you have photographs and other detailed technical information readily available to the review group.

For the purpose of this example, assume the 1,000 GPM pump at the beginning of the fuel supply system is exactly like the one depicted in Figure 5-2. To illustrate the process of failure modes and failure effects, the dog walk is restricted primarily to this pump. Bear in mind that the process used for this pump is identical to the process one would use for the remainder of the system.

Figure 5-2: Fuel supply pump

Tip from  Reliability Centered Maintenance: Unraveling the Mysteries by Jim Gehris