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Main/OneNote/OSD/Safety/DO-254 Summary.md
2024-12-02 15:11:30 +01:00

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**Simple and Complex hardware item:**
_Something is simple if a comprehensive combination of deterministic tests and analyses ensures correct functional performance under all foreseeable operating conditions with no anomalous behavior._
Everything else is a complex item.
- Simple hardware item: extensive documentation is unnecessary.
- Complex items: design assurance should be agreed to by the certification authority.
- Hierarchically analyse all levels for complexity. Include functions that are not testable such as unused modes or hidden states in sequential machines.
# System Aspects of Hardware Design Assurance
1. # System Aspects of Hardware Design Assurance
2. Allocate System functions to hardware (or software or combination of both)
3. Assign system development assurance levels
![FAR/JAR and Advisory Material
Systems
Safety
Assessment
Safety/
Hardware
Hardware
Safety/
Software
Safety/
Hardware/
Software
Software
Hardware
Software
Figure 2-1 Relationships Among Airborne Systems, Safety Assessment,
Hardware and Software Processes ](Exported%20image%2020231126172017-0.png)
Overlaps are important: hardware function that contains safety requirements invokes safety assessment process and hardware design life cycle process.
- 3 Processes work in parallel:
- System Development Process
- Hardware Design Life Cycle Process
- Software Life Cycle Process
- Design assurance level: [defined](https://en.wikipedia.org/wiki/DO-178C) by impact on passenger safety.
-
- ![Level
A
B
C
D
E
Failure condition
Catastrophic
Hazardous
Major
Minor
No Safety Effect
[11]
Objectives
71
69
62
26
With independence
30
18
5
2 ](Exported%20image%2020231126172017-1.png)
- Objective with independance: another person must verify the item.
Questions
- [ ] What is our software assurance process
Todo:
- [ ] Define functions with associated requirements,
failure conditions and design assurance level
Review:
- [ ] Chap2