Parts selection should be guided by the NASA Parts Selection List (NPSL) and GSFC 311-INST-001, both of which provide for 3 part levels. 

Level 1 parts are inherently low risk and are suitable for use in all applications including life support, mission critical, single-string and single-point failure.  Level 1 active parts should be reviewed for radiation hardness. 

Level 2 parts have inherently higher risk than level 1 and are considered moderate risk.  Level 2 parts are suitable for most general purpose space flight applications but are not recommended for life support, mission critical, single-string or single-point failure applications unless there is on-orbit reparability.  Level 2 active parts need to be evaluated for radiation hardness. 

Level 3 parts are inherently high risk because there is little dependable data or history available for them and changes in their materials, designs and processes may occur continuously without notification.  Level 3 parts are intended for mission applications where the use of high risk parts is acceptable.  Level 3 parts should not be used in single-point failure or single-string applications unless a very high risk for failure or malfunction is acceptable.  Level 3 parts must be evaluated for radiation hardness, radiation testing is recommended. 

The inherent risk of the parts selected may be mitigated to meet application needs by qualification and up screening, in accordance with GSFC 311-INST-001.  The project manager shall approve the quality level selected for the application.


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Michael J. Sampson
Manager, NASA EEE Parts Assurance Group (NEPAG)