Ambient conditions are those involving temperature

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Ambient conditions are those involving temperature, humidity, lightning, electromagnetic effects, radiation, precipitation, vibration, etc. (c) UPES, Not for Reproduction/ Sale
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UNIT 16: Principle of System Safety Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ SHELL Model In the SHELL model, the match or mismatch of the blocks (interface) is just as important as the characteristics described by the blocks themselves. These blocks may be rearranged as required to describe the system. A connection between blocks indicates an interface between the two elements. Figure 16.7: SHELL Model of a System Each element of the system should be described both functionally and physically if possible. A function is defined as, “An action or purpose for which a system, subsystem, or element is designed to perform.” 1. Functional description: A functional description should describe what the system is intended to do, and should include subsystem functions as they relate to and support the system function. 2. Physical characteristics: A physical description provides the audience with information on the real composition and organization of the tangible system elements. As before, the level of detail varies with the size and complexity of the system, with the end objective being adequate audience understanding of the safety risk. 3. Both models describe interfaces: These interfaces come in many forms. The Table 16.6 is a list of interface types that the system engineer may encounter. (c) UPES, Not for Reproduction/ Sale
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Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ Aviation Safety & Security Management Table 16.6: List of Interface Types with Examples Interface Type Examples Mechanical Control Data Physical Electrical Aerodynamic Hydraulic Pneumatic Electromagnetic RF signals from a VOR . A radar transmission. Transmission of torque via a driveshaft. Rocket motor in an ejection seat. A control signal sent from a flight control computer to an actuator. A human operator selecting a flight management system mode. An adiabatic expansion cooling unit supplying cold air to an avionics bay. An air compressor supplying pressurized air to an engine air turbine starter. Pressurized fluid supplying power to an flight control actuator. A fuel system pulling fuel from a tank to the engine. A stall indicator on a wing. A fairing designed to prevent vortices from impacting a control surface on an aircraft. A DC power bus supplying energy to an anti-collision light. A fan plugged into an AC outlet for current. An electrical circuit closing a solenoid. An avionics rack retaining several electronic boxes and modules. A computer sitting on a desk. A brace for an air cooling vent. A flapping hinge on a rotor. A position transducer reporting an actuator movement to a computer. A cockpit visual display to a pilot. Check Your Progress Fill in the blanks: 1. 5M Model of System Engineering consists of Man, Machine, Management, …………… and ……………. 2. The four elements of the SHELL Model of a system represent Software, Hardware, …………… and ……………. Summary This unit explains the principles of system safety. The Five-step approach to system safety has been described in this unit. System
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  • Fall '19
  • Instrument approach, Runway, Rajiv, Aviation Safety & Security Management

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