A top-down SFP analysis of a complex system

The single-failure points (SFPs) in a system can be found by either bottom-up or top-down analysis, since each SFP must cause a significant system-level failure effect. For a large complex system, top-down analysis can be more efficient. The authors present, as an example, a high-pressure air heater and its pressure controller, which are part of a hypersonic wind tunnel. The failure effect of concern is heater overpressurization. At least one failure in the pressure controller and one or more in the application safety features would be required for overpressure to occur. It is therefore concluded that there are no SFPs for heater overpressurization in this wind tunnel