Fault Tree for Safety
Abstract
Effective system safety engineering requires a method for examining proposed designs, identifying potential undesirable events, and recommending solutions that will prevent those events from occurring. To accomplish this, the Fault Tree technique was conceived in 1962. Subsequently, Boeing successfully applied the technique to the Minuteman ICBM system. Recent refinement of the technique has permitted its adaptation to dynamic systems such as aircraft. The same desirable features that gained Fault Tree its wide acclaim on Minuteman has been retained in its adaptation to aircraft systems. The Fault Tree process utilizes logic diagrams to portray and analyze potentially hazardous events. As employed by Boeing, this involves the following six steps: (1) Define undesired event, (2) Acquire understanding of system, (3) Construct fault tree, (4) Collect quantitative data, (5) Evaluate fault tree probability, (6) Analyze computer results. Three basic symbols (logic gates) are adequate for diagramming any fault tree. However, additional recently developed symbols can be used to reduce the time and effort required for analysis. In addition, use of a new technique, called 'Importance Sampling' for generating failure occurrences serves to dramatically reduce the amount of computer time required to produce quantitative results. Fault Tree analysis can be applied to virtually any system, design, or procedure with positive results. It fills the need for a quantitative safety analysis capable of extreme detail. In addition, it provides an extremely useful tool in determining the weak points in a design, whether or not numerical analysis is applied.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 08, 1968
- Accession Number
- AD0847015
Entities
People
- A. F. Hixenbaugh
Organizations
- Boeing