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Instructions for EEE Parts Selection, Screening, Qualification and Derating

1.0 PURPOSE
The purpose of this document is to establish baseline criteria for selection, screening, qualification, and
derating of BBB parts for use on NASA GSFC space flight projects. This document shall provide a
mechanism to assure that appropriate parts are used in the fabrication of space hardware that will meet
mission reliability objectives within budget constraints.
All acronyms used in this document are listed in the acronym table at the end of this section on pagel l.
2.0 SCOPE
This document provides instructions for meeting three reliability levels of BBB parts requirements (see
6.0) based on mission needs. The terms “grade” and “level” are considered synonymous; i.e., a grade 1
part is consistent with reliability level 1. Levels of part reliability confidence decrease by reliability
level, with level 1 being the highest reliability and level 3 the lowest. A reliability level 1 part has the
highest level of manufacturing control and testing per military or DSCC specifications. Level 2 parts
have reduced manufacturing control and testing. Level 3 Parts have no guaranteed reliability controls in
the manufacturing process and no standardized testing requirements. The reliability of level 3 parts can
vary significantly with each manufacturer, part type and LDC due to unreported and frequent changes in
design, construction and materials.
GSFC projects and contractors shall incorporate this guideline into their Project EEE Parts Program.
3.0 DEFINITIONS
Screening. Screening tests are intended to remove nonconforming parts (parts with random defects that
are likely to result in early failures, known as infant mortality) from an otherwise acceptable lot and thus
increase confidence in the reliability of the parts selected for use.
Qualification. Qualification testing consists of mechanical, electrical, and environmental inspections,
and is intended to verify that materials, design, performance, and long-term reliability of the part are
consistent with the specification and intended application, and to assure that manufacturer processes are
consistent from lot to lot.
Derating. Derating is the reduction of electrical and thermal stresses applied to a part during normal
operation in order to decrease the degradation rate and prolong its expected life.