(P)robability

(S)everity

(D)etection

Value

Description

D

1

Certain - fault will be caught on test

D

2

Almost certain failure can be detected prior to reaching Operators or Maintainer

D

3

High probability failure can be detected prior to reaching Operators or Maintainers

D

4

Moderate probability failure can be detected prior to reaching Operators or Maintainers

D

5

Low probability failure can be detected prior to reaching Operators or Maintainers

D

6

Fault is undetected by Operators or Maintainers

P

1

Extremely Unlikely (Virtually impossible or No known occurrences on similar products or processes, with many running hours)

P

2

Remote (relatively few failures)

P

3

Occasional (occasional failures)

P

4

Reasonably Possible (repeated failures)

P

5

Frequent (failure is almost inevitable)

S

1

No relevant effect on reliability or safety

S

2

Very minor, no damage, no injuries, only results in a maintenance action (only noticed by discriminating customers)

S

3

Minor, low damage, light injuries (affects very little of the system, noticed by average customer)

S

4

Moderate, moderate damage, injuries possible (most customers are annoyed, mostly financial damage)

S

5

Critical (causes a loss of primary function; Loss of all safety Margins, 1 failure away from a catastrophe, severe damage, severe injuries, max 1 possible death )

S

6

Catastrophic (product becomes inoperative; the failure may result in complete unsafe operation and possible multiple deaths)