COMPARISON OF RISK FACTORS FOR LEVELS 1,2 & 3 - PASSIVE PARTS

Spec Controlled Quality/Risk Factor

Level 1   4/

Level 2   5/

Level 3   6/
       
ER Specification          1/ Yes Yes No
SCD Prepared              2/ Not required Not required Required
Material Control           3/ Yes Yes No
Process Controls          3/ Yes Yes No
Lot Control                   3/ Yes Yes No
Traceability                 3/ To raw materials To raw materials Unknown
Failure Rate                3/ Better than 0.01%/1000 hrs Better than 0.1%/1000 hrs None
Qualification Testing 3/ Yes Yes No
Life Test                      3/ Yes Yes Rarely
Periodic QCI               3/ Yes Yes No
1/ Parts procured to an Established Reliability specifications do not require any additional
testing or inspection (Procure them and use them as is).
2/ For Level 3 a detailed procurement specification would need to be prepared  and coordinated with the
 manufacturer to insure the part meets the Project requirements, this would include tests to bring the
 level 3 part to flight worthiness. This is very costly (16 to 30 hrs of Specialists time plus testing).
3/ Included as part of the Established Reliability specification at no additional cost. This is normally 
non-existent with Level 3 parts.
4/ Level 1 with a failure rate of 0.01%/1000 hrs, requires that the manufacturer accumulate 31,100,000
part hours of testing over a twelve month period  to insure the reliability of the parts at a 60% confidence level.
5/ Level 2 with a failure rate of 0.1%/1000 hrs, requires that the manufacturer accumulate 3,110,000 part hours
 of testing over a twelve month period  to insure the reliability of the parts at a 60% confidence level.
6/ Level 3 is Commercial Off The Shelf (COTS) parts with no reliability or failure rate levels established. Also in 
most cases the temperature ranges the parts can operate over are considerably restricted compared to Level 1
& 2 parts. (Example Level 1 & 2 temp range -65°C to +125°C. Level 3 temp. range can be only -20°C to +85°C).