page 191

are present. For example heat flow across a conductor.

• This analysis is best done by a team of experts familiar with the modules being interfaced.

8.1.8 Management of Reliability

8.1.8.1 - Preliminary Hazard Analysis (PHA)

•As the name suggests this procedure is carried out early in projects.

•typically this involves,

-determining hazards that might exist and possible effects

-determine a clear set of guidelines and objectives to be used during a design

-create plans to deal with critical hazards

-assigning responsibility for hazard control (management and technical)

-allocate time and resources to deal with hazards

•The results of this analysis are used for preparing specification, testing, implementation, maintenance and management.

•The modules within the system must be clearly identified, with consistent boundaries.

•Specific hazards may be obvious, or they may be mandated by government regulations.

•Some hazards can be identified by,

-examining similar existing systems

-review existing checklists and standards

-consider energy flow through the system

-consider inherently hazardous materials

-consider interactions between system components (e.g., materials corrode or power drain)

-review previous hazard analysis for similar systems

-review operation specifications, and consider all environmental factors

-use brainstorming in teams

-consider human/machine interface

-consider usage mode changes

-try small scale testing, and theoretical analysis

-think through a worst case what-if analysis

•Hazard forms are not completed all at once, but as project steps develop.