SYS RAMS FS17
SYS RAMS FS17
SYS RAMS FS17
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Lernkarten
Less low level OR-Gates in the FTA
Summary of lower level failure Modes with the same effect from the FMEA
Fault Tree Analysis Top-Down system which represents the causes of a system failure mode, in terms of the specific component failure modes
Minimal combinations of component failures for system failure
Probability of frequency of the system failure
All events have to happen in a specific order.
m events out of n possibilities have to happen
external factor which may happen or not. P(1) or P(0)
If further resolution of the event is not necessary or not available
They are always used together, inhibit events occurs when the conditional event is met as well as an additional one.
Time between the last time known that it worked properly till time known that it will wokr properly again.
Time in which item has to fail to cause the failure
Preliminary System Safety Assessment Tow-Down approach; examination of architecture to find out how failures can lead to failure conditions figured in FHA
Select inputs, functional mapping of architectural features and failure conditions
high degree of knowledge and understanding of the system and the specific functions causing a failure condition
Ensure that no single physical failure produces an catastrophic event Identify all latent failures that have a latency period for longer than one flight cycle
Safety System Assessment Bottom-Up-Approach; Verification that the Design met the Safety Requirements
Software plans, Requirements, Design, Code/Integration, Review/Analysis, Testing
What does the software? Helps reducing errors, defines a correct testing: reducing cost, increasing safety
Initial Airworthiness Continued Airworthiness
Remove Requirements/Design errors Maintain Configuration control of the final design
Because requirements are set on each abstraction level working top-down. Traceability has to be seen between the steps. Bottom-up can lead to surprises back at the top, this would lead certification requirements to high risks.
A-Check (800 Fh, 140 days; nightstop) C (2 years, 7500 Fh; 4-5 days) IV, D-Checks (6 years, 2-4 weeks)
E-Checks (800 Fh, 66 days; nightstop) IL-Check (6 years, 2-3 weeks)
Maintenance Review Board Report Document provided by A/C manufacturer, overview of all maintenance points
Maintenance Planning Document Based on MRBR; tells exactly how to maintenance
Airline Aircraft Maintenance Programm 1. Introduction 2. Summary of Changes / cross references to MRBR, MPD, AD, etc. 3. Maintenance Program Tasks (below example) 4. Components and Life Limits 5. Reliability Program
Reliability Program Ensures that AMP is effective and periodicity is adequate.
in the real world, an engineer may be limited by technology, economics, ability, skill, network
Some components will deteroriate or even lack of use. Perfection level sinks with time.
regularly Maintenance to restore the system and bring it back to a solid perfection level with less entropy. = scheduled maintenance
Only components with definite life time limits and/or wear out periods will benefit from scheduled maintenance!
1. Redundant Systems 2. Line Replaceable Unit (quick replacement, failed part can be repaired later) 3. Minimum Equipment List
1) Hard Time (Components with definite limits) 2) On-Condition (Components be regularly checked to determine remaining seviceability) 3) Condition Monitoring (monitoring of failure rates, removal rates to facilitate maintenance planning)
MSG-1, MSG-2 (Bottom-Up) "components are the most likely causes of equipment malfunction"
Top-Down Approach which asks: how does a particular failure affects the operation of the aircraft?
Aircraft Systems/Powerplant Tasks Aircraft Structural Tasks Aircraft Zonal Tasks
Lubrication Servicing Inspection Functional Check Operational Check Visual Check Restoration Discard
1) Environmental deterioration 2) Accidental Damage 3) Fatiuge Damage
Different zones are built over all systems (overlapping them), to pay enough attention to every system
