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SYS-RAMS

Reliability, Availability, Maintainability and Safety

Reliability, Availability, Maintainability and Safety

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Set of flashcards Details

Flashcards 115
Language English
Category Technology
Level University
Created / Updated 19.02.2020 / 05.01.2023
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AFM

Airplane Flight Manual

DDG

Dispatch Deviation Guide
JAA

Joint Aviation Authorities

CMCC

Certification Maintenance Coordination Committee

ISC

Industry steering Committee

CRI

Certification Review Item

AC

Advisory Circular

ATA

Air Transport Association

SAE

Society of Automotive Engineers, Inc.

MSG-3

Maintenance Steering Group 3
MTTF

Mean Time To Failure

DAD

Design Approval Designee

APU

Auxiliary Power Unit

MC

Maintenance Checks
R, M & S

Reliability, Maintainability and Safety

FC

Failure Condition

ACJ

Advisory Circular Joint

MEL

Minimum Equipment List
CVE

Compliance Verification Engineer

CCA

Common Cause Analysis

FAR

Federal Aviation Regulation

Airworthiness

Measure of an aircrafts suitability for safe flight (design, manufacturing, operation and maintenance).

Type Certification

Process by which the Certifying Authority determines that an aircraft meets the applicable Rules and Regulations.

What aircraft does FAR/CS 23 apply to?

small aircraft

What aircraft does FAR/CS 25 apply to?

large Aircraft

What aircraft does FAR/CS 27 apply to?

small helicopters

What aircraft does FAR/CS 29 apply to?

large helicopters

Classification of Failure Conditions:

  • No Safety Effect
  • Minor
  • Major
  • Hazardous
  • Catastrophic

Effect on Aeroplane, of each "failure condition class":

No safety effect:   No effect on operational capabilities or safety
Minor:   Slight reduction in functional capabilities or safety margins
Major:   Significant reduction in functional capabilities or safety margins
Hazardous:   Large reduction in functional capabilities or safety margins
Catastrophic   Normally with hull loss

Effect on Occupants (excluding Flight Crew) for each "failure condition class":

No safety effect:   Inconvenience
Minor:   Physical discomfort
Major:   Physical distress, possibly including injuries
Hazardous:   Serious or fatal injury to a small number of passengers or cabin crew
Catastrophic   Multiple fatalities

Effect on Flight Crew for each "failure condition class":

No safety effect:   No effect on flight crew
Minor:   Slight increase in workload
Major:   Physical discomfort or a significant increase in workload
Hazardous:   Physical distress or excessive workload impairs ability to perform tasks
Catastrophic   Fatalities or incapacitation

Allowable Qualitative Probability for each "failure condition class":

No safety effect:   No Probability Requirement
Minor:   Probable
Major:   Remote
Hazardous:   Extremely Remote
Catastrophic:   Extremely Improbable

Allowable Quantitative Probability for each "failure condition class":
Average Probability per Flight Hour on the Order of:

No safety effect:   No Probability Requirement
Minor:   <10-3
Major:   <10-5
Hazardous:   <10-7
Catastrophic:   <10-9

probabilities in: one failure per X flight hours

Define reliability:

Reliability is an item characteristic expressed by the probability that this item will perform its intended function under specified operating conditions, without failure, for a specified period of time.

Define failure:

  • An event which causes the system performance to deviate from the specified performance.
  • The termination of the ability of an item to perform its required function
  • LOSS OF FUNCTION or ERRONEOUS OPERATION

A failure condition can occur ... or ... .

randomly, progressive

Active Failure:

  • is evident at the moment of occurrence
  • produces an effect
  • this effect can be also the indication of the monitoring system

Latent (Dormant) Failure:

  • is not immediately observable at the moment of occurrence
  • produces no immediate effects
  • is not indicated by the monitoring system

Active and Passive Failure:

Active Failure: A failure that can potentially produce a large input in the system
Passive Failure: A failure that can be observable but will not produce an input in th esystem
Example: Hydraulic Actuator

FAILURE1: Reduction of Hydraulic Flow
Observable (reduction in performance)
Does not generate an input into th esystem
⇒ Passive Failure

FAILURE 2: Erroneous Motion of the Servovalve
A motion of the servovalve will generate a motion of the actuator arm
Does generate an input into the system
⇒ Active Failure

Discuss the following sentence: Safety is "The state in which risk is acceptable".

State:

  • In the context of an aircraft development “state” refers to the implementation of the aircraft design.
  • State = “implementation of the aircraft design”
  • This means, that the aircraft is designed, developed, produced, maintained and operated correctly

Risk:

  • Estimation of the seriousness, the likelihood of occurrence and the potential for harm.
  • combined analysis of
    • Hazard (The potential for harm arising from an intrinsic property or
      disposition of something to cause detriment.
    • Probability
      A measure or estimation of thelikelihood of occurrence of an event.
    • Severity
      The seriousness of something undesirable.

Acceptable:

  • Acceptable to:
    • The users of the aircraft (e.g. passengers)
    • The general public
    • the (civil) certification authority

System Safety is (state in which risk is acceptable):
the implementation of an aircraft design…
…in which the seriousness and the likelihood of occurrence…
…of the potential fo rharm…
…to the passengers and the general public…
…is acceptable!

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