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【范围】
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This document describes guidelines and methods of performing the safety assessment for
certification of civil aircraft. It is primarily associated with showing compliance with FAR/JAR
25.1309. The methods outlined here identify a systematic means, but not the only means, to show
compliance. A subset of this material may be applicable to non-25.1309 equipment. 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.
1.1 Purpose:
This 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)].
1.2 Intended Users:
The intended users of this document include, but are not limited to, airframe manufacturers,
system integrators, equipment suppliers and certification authorities who are involved with the
safety assessment of civil aircraft and associated systems and equipment.
1.3 How To Use This Document:
The guidelines and methods provided in this 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 this 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.
This document provides general guidance in evaluating the safety aspects of a design. The
primary analytical methods and tools and the relationship of these are introduced. Users who
need further information on a specific method or tool may obtain detailed information from
appendices A through K. These appendices provide information on Functional Hazard
Assessment (FHA), Preliminary System Safety Assessment (PSSA), System Safety
Assessment (SSA), Fault Tree Analysis (FTA), Dependence Diagram (DD), Markov Analysis
(MA), Failure Modes and Effects Analysis (FMEA), Failure Modes and Effects Summary
(FMES), Zonal Safety Analysis (ZSA), Particular Risks Analysis (PRA) and Common Modes
Analysis (CMA). Appendix L provides an example of the safety assessment process for a
hypothetical system. This contiguous example illustrates the relationships between the
processes and methods in creating the overall safety evaluation of an aircraft or system as it
develops through the design cycle.
NOTE: The appendices are not stand alone documents, but are intended to be used in
conjunction with the information contained in the basic document. The user is
cautioned not to use the appendices independent of the basic document.
Further, the examples in the Appendix L “Contiguous Example” should not be
used without making reference to the corresponding appendix and to the main
body of this document.
Examples presented in this document, including documentation examples, are intended only as
guidance. The examples should not be interpreted as an addition to or an amplification of any
requirement.
Throughout this document and the appendixes, reference is made to using Fault Tree Analyses.
It should be understood by the reader that Dependence Diagrams or Markov Analyses may be
selected to accomplish the same purpose, depending on the circumstances and the types of
data desired.
ARP1834 and ARP926A contain information about Fault/Failure Analysis but are superseded by
this document for purposes of civil aircraft safety assessment. They are being amended to
reflect this supersession.strRefField
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