What you missed from the SAE meeting regarding aircraft wire testing
If you had other business commitments and couldn't make the recent SAE 8A/D meeting this week that included topics related to aircraft wire testing, we have put together a quick summary from the committee meetings.
RoHS Compliance
The Reduction of Hazardous Substances (RoHS) has been something the aerospace industry has been struggling to comply with for years. As a standards committee, the SAE 8D (wire and cable group) must respond to industry demands and have standards that identify the products as being RoHS compliant. However, if there are manufacturers that cannot (or will not) meet the RoHS compliance requirements, then the 8D committee may create separate slash sheets for those non-RoHS compliant products. What could this mean? The possible addition of 30 slash sheets to the AS22759 wire group.
Acceptance of Silver Plated Wires
One of the problems being experienced by some is determining the damage tolerance and acceptance of silver plating for conductors and cable shields. The concern with damaged plating is that the exposed copper provides an excellent site for initiation of corrosion, particularly red plague, as the Wire Degradation and New Research on Red Plague article shows.
Unfortunately, the manufacturing of silver plated conductors and shields is not a perfect process. During the conductor extrusion process, the conductor fabrication, and the insulation application, the conductor may get nicked. But what level of damage is acceptable?
The process that at least one conductor manufacturer uses is to examine the first foot of a conductor run for defects. This is a visual examination looking for repeated nicks or long sections of platting damage. If repeat damage is found on the first foot, then an additional section of the wire is examined. If more flaws are found, then the wire is rejected.
What it comes down to is an agreement between the customer and producer as to the acceptance criteria.
Changes Hitting the 50881
The most important document of the SAE 8A committee is the AS50881. During this week’s discussions, a number of changes were approved. Here are a couple of the most important ones:
- Clarification of boundaries: In previous iterations of the AS50881, the short wire runs that joined Line Replaceable Units (LRUs) were not clearly identified as electrical wire interconnection systems (EWIS). Additional language was added to clearly state that these LRU interconnections also fall under the jurisdiction of 50881.
- Preparation of equipment grounding: Language was added addressing the preparation and installation of grounding modules on aircraft.
- Next revision of 50881: Although the last revision of 50881 was released late last year, the committee agreed that several of the changes were critical and should be integrated into the newest version as soon as possible. It is likely that we will see the next version of the 50881 out for ballot within the next six months.
We will expand on most of these items in upcoming articles.