Notes on NASA-STD-8739.4

The following are notes on NASA-STD-8739.4, the Workmanship standard for Cable, Crimp and Harness.  These notes do not represent requirements but are intended for information only.

NOTE1.  Future Changes to NASA-STD-8739.4A

The following changes are planned for the next revision of the NASA Cable Harness Standard:

a. Pg. 40, paragraph 9.9.2:  Remove third sentence "Sleeving coverage dimensions are given in this figure."  Reason:  Sleeving overlap dimensional requirements are defined in 9.8.5 and are relative to the diameter of the wire or cable.  Having a specific overlap dimension in the image implied a requirement that was not traceable to 9.9.2.  The dimension numbers were removed in Rev A but the sentence was missed for removal.

b. Pg.  50, Figure 11-7: Remove "DIMENSIONS IN MILIMETERS (INCHES)".  Reason:  These words were overlooked for removal.  The dimension numbers were removed from this image to avoid their use directly as a requirement rather than 9.9.2 (also see a. above).

NOTE 2.  Adoption of Industry Standards as Replacements for NASA Standards. 

In 1998, NASA established by internal mandate, the need for all NASA standards users and custodians, to comply with the 1995 Office of Management and Budget (OMB) Circular A-119 on Federal Participation in the Development and Use of Voluntary Consensus Standards and in Conformity Assessment Activities.  This directive compels the NASA Workmanship Project to actively identify, enhance and adopt industry standards which can be used in lieu of the NASA-STD-8739 series documents. 

IPC/WHMA-A-620xS was been identified as a candidate alternative for NASA-STD-8739.4.  Drafts of this document and comments made by NASA to the coordinating committee may be accessed via the IPC committee webpage:  http://www.ipc.org/committeedetail.aspx?Committee=7-31fs  Adoption was completed effective June 19, 2017.

NOTE 3.  DWV test condition vs Connector and Wire Voltage Ratings

DWV testing of connectors and wire insulation is normally performed at high voltage for a very short duration to drive weak areas in connector inserts and in wire insulations to failure so that they do not present as infant mortal failures during ground testing or in the mission.  These test conditions do not overstress "good" parts and are routinely used for screening of high reliability connectors and wire/cable.  Connector and wire specifications document applicable DWV voltage "rating".