Reliability & 1309 Design Analysis of Aircraft Systems

100 Pages·2014·3.37 MB·English

by  Marge Jones

Melding DoD and FAA System Safety
Methods
 Blending SAE ARP4761 and MIL-STD-882E processes
Presented To: 2014 International System Safety Society Conference
St. Louis, MO
Presented By: Marge Jones
Commercial Aircraft Safety
Commercial Projects Government Direct Projects
Process Training
Safety Analytical University of Kansas
PPT Solutions Inc.
Technologies, Inc. Aerospace Short Course
Huntsville, AL Huntsville, AL
[email protected] www.pptsinc.com http://aeroshortcourses.ku.edu/
SAE International did not authorize including their copyrighted material in electronic versions of this presentation. The following
provides a summary of the ARP material that will be needed:
ARP4761 ARP4754A
Figure 2, p.18 Figure 7, p. 33
Section 2.2, p. 12
Section 5.2.3.2.1.1, pp. 41 & 42
Figure 9, p. 45
Table 4, p. 46
Table 3, p. 44
Figure 10, p. 48
Table 5, p. 49
Section 5.2.4, p.50
Figure 11, p. 51
Objective
 Highlight the differences and similarities
between MIL-STD-882E and associated Data
Item Descriptions (DIDs) with the commercial
aircraft system safety process (14CFR2X.1309,
AC2X.1309, SAE ARP4761 and ARP4754)
 By understanding the differences and
similarities, Statement of Work and CDRL
requirements can be tailored to define a
blended system safety process that could
satisfy both
 FAA regulations are law – shall comply. Less flexible
in terms of techniques or methods for showing of
compliance. Always coordinate with Customers
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Melding DoD and FAA System Safety
Methods
 Similarities
 Same Basic System Safety Concept
 Order of Precedence for applying risk mitigation
 Tied to Development Process
 Analytical techniques defined by specific objectives
 Differences
 Applicability and Diversity of Systems
 Terminology
 Acceptable Risk Concept
 Technique for consideration of software/logic devices
contributions
 Specific analytical techniques and documentation
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Blended “Safety” Definition
 PHYSICAL Safety is dependent
upon inherent characteristics of the
component, system, etc.
Physical
 Usually can be thought of stored energy
or energy transfers
 OPERATIONAL Safety is usually
thought of in terms of the user
environment
Functional Operational
 How, when, by whom, etc..
 FUNCTIONAL Safety is dependent
From: “Aircraft System Safety, Military
upon correct performance of and Civil Aeronautical
Applications,” Duane Kritzinger
intended function
 and “control” of unintended functions:
loss of, malfunctions, etc…
 Any safety process MUST
address all these aspects!
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Outline
 Basic System Safety Concept
 Background on Commercial Aircraft Safety
Process and MIL-STD-882 Process
 Show integration with development
 Methods for Consideration of Software to
Hazards
 Definitions – Conflicts
 Comparison of Analysis Tasks
 All Tasks
 FHA, PSSA, SSA/SAR details
 Safety Planning
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System Safety Basic Concept/Process
Identify the “Threat”
[hazards/ hazardous
conditions/ failure
conditions/ unsafe Identify Safety “Risk” Requirements
conditions]
Assess the Severity and
Establish Safety
Identify Safety “Solutions” Requirements
Objectives
Develop Mitigation
Strategies
[Architecture,
Operational, and/or
Ensure all “Solutions” Identified
Installation]
Determine Effectiveness
of Mitigation Strategies
[Acceptable Risk]
Verify Requirements Met
Verify Implementation of
Mitigation Strategies
© 2014. Safety Analytical Technologies, Inc.
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ARP4761 System Safety Process - Documentation
Identify the “Threat”
[hazards/ hazardous
conditions/ failure
conditions/ unsafe PSSA
conditions]
Assess the Severity and
Establish Safety
FHA
Objectives
Develop Mitigation
SSA
Strategies
[Architecture,
Operational, and/or
Installation]
Determine Effectiveness
of Mitigation Strategies
[Acceptable Risk]
FHA - Functional Hazard Assessment
Verify Implementation of
PSSA – Preliminary System Safety Assessment Mitigation Strategies
SSA – System Safety Assessment
© 2014. Safety Analytical Technologies, Inc.
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ARP4761 System Safety Concept/Process
Identify Safety “Risk” Requirements
DEFINE SAFETY
OBJECTIVES/
REQUIREMENTS
Functional Hazard
Identify Risk Mitigations (Safety Requirements)
Assessment
Ensure all Safety Requirements Identified
VALIDATE SAFETY
OBJECTIVES/
REQUIREMENTS
Preliminary System
Safety Assessment
Verify Requirements Met
VERIFY SAFETY
OBJECTIVES/
REQUIREMENTS
System Safety
Assessment
© 2014. Safety Analytical Technologies, Inc.
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Safety Assessment Process Overview
(ARP4761)
Physical
Aircraft/System
Hazards
Architecture
(Particular Risk,
Definition
Common Mode)
System Safety
Contribution to Requirements
Determine Failure Condition (assurance, red.,
Severity Establish [DD, FTA, Markov, prob., install,
Safety
Establish Common Mode, etc.)
Identify Objectives
Compliance FFMEA]
Functional Equipment
Method (Safety
Failures Safety
Analyses, etc.)
Requirements
Software/CEH (assurance,
Safety redundancy,
Requirements prob., etc.)
VALIDATE SAFETY
(assurance,
OBJECTIVES/
functions, etc.)
Aircraft FHA System FHA
REQUIREMENTS
Preliminary System
Safety Assessment
System
Safety Analysis
Item Safety
[F-FMEA, FTA,
DEFINE SAFETY Analysis [Pred,
CCA]
OBJECTIVES/ FMEA, FTA,
Aircraft
REQUIREMENTS CCA]
Safety Analysis
[FTA, CCA]
Functional Hazard
Assessment
VERIFY SAFETY Assurance
FTA – Fault Tree Analysis
OBJECTIVES/ Process
DD – Dependency Diagram REQUIREMENTS Test Data; Verification
Data
Stress,
FMEA – Failure Mode and Effects Analysis System Safety Performance,
Assessment
etc.. Analyses
CCA – Common Cause Analysis
9 © 2014. Safety Analytical Technologies, Inc.