The concept of Aircraft Level Safety Assessment is introduced and the tools to accomplish this task are outlined. The overall aircraft operating environment is considered.
When aircraft derivatives or system changes are certified, the processes described herein are usually applicable only to the new designs or to existing designs that are affected by the changes. In the case of the implementation of existing designs in a new derivation, alternate means such as service experience may be used to show compliance.
The ARP 4761 document presents guidelines for conducting an industry accepted safety assessment consisting of Functional Hazard Assessment (FHA), Preliminary System Safety Assessment (PSSA), and System Safety Assessment (SSA). This document also presents information on the safety analysis methods needed to conduct the safety assessment. These methods include the Fault Tree Analysis (FTA), Dependence Diagram (DD), Markov Analysis (MA), Failure Modes and Effect Analysis (FMEA), Failure Modes and Effects Summary (FMES) and Common Cause Analysis (CCA). [CCA is composed of Zonal Safety Analysis (ZSA), Particular Risks Analysis (PRA), and Common Mode Analysis (CMA)].
The guidelines and methods provided in ARP 4761 document are intended to be used in conjunction with other applicable guidance materials, including ARP4754, RTCA/DO-178, RTCA SC-180 Document DO-(TBD), and with the advisory material associated with FAR/JAR 25.1309. (For engines and propeller applications, reference the applicable FAR/JAR advisory material.) The intent of ARP 4761 document is to identify typical activities, methods, and documentation that may be used in the performance of safety assessments for civil aircraft and their associated systems and equipment. The specific application of such activities needs to be established by the organization conducting the assessment and the appropriate recipient.
RAM Commander Safety Assessment Software
FRACAS - Failure Data Collection and Safety Management System