Avionics News April 2012 - 42

A 2008 aircraft wiring degradation study conducted by Raytheon Technical Services for the FAA found chafing was caused by oversized, loose or out of alignment clamps, which allowed cables to move and vibration from contact with the aircraft structure and/or components, such as fuel lines.

AirCrAft eleCtriCAl wiriNg
Continued from page 41

splices and connector pins, bad solder connections and improper use of parts” and warning that cable bundles should never be pulled through clamps that have not been removed or loosened. While your shop always takes care to avoid such obvious errors, there’s no way to know whether every technician who worked on an airplane in the past was equally conscientious. The FAA identified wiring as a significant problem some years back – so significant that it created a whole new acronym: Aircraft Electrical Wiring Interconnect System (EWIS). This was intended to elevate boring old wiring to a co-equal status with other major aircraft systems. Chapter 11 of FAA advisory circular 43.13-1B, Acceptable Methods, Techniques, and Practices – Aircraft

Inspection and Repair governs “inspection and care of electrical systems.” While focused on transport category aircraft, it is widely used as a standard for light aircraft as well. Chapter 11 opens with a 15-point list of items to be inspected during routine electrical system maintenance, and proceeds through 20 sections covering, among other things, wire ratings, wiring installation and inspection, plastic tie strips, clamping, splicing and termination. It’s available free on the FAA website. In 2010, the FAA announced its intention to accept consensus standards from ASTM International as “acceptable means of compliance to 14 CFR Part 23 sections concerning electrical wiring systems… for normal, utility, acrobatic and commuter category airplanes.” ASTM F2639-07 covers design, alteration and certification of
Continued on page 44

For MorE InForMAtIon
 AEA ONlINE TRAINING www.aea.net/training/online  AIRCRAFT WIRING DEGRADATION STuDY www.tc.faa.gov/its/worldpac/techrpt/ar082.pdf  ADvISORY CIRCulAR 43.13-1B www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861  ASTM F2696 – 08 www.astm.org/Standards/F2696.htm  FAA “EWIS BEST PRACTICES” JOB AID www.faa.gov/training_testing/training/air_training_program/job_aids/media/EWiS_job-aid_2.0_Printable.pdf  INTERNATIONAl AvIATION SAFETY ASSOCIATION WIRING ISSuES www.iasa.com.au/folders/Safety_issues/Aircraft_Wire/index.htm

42

avionics news

•

april

2012

http://www.aea.net/training/online http://www.tc.faa.gov/its/worldpac/techrpt/ar082.pdf http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861 http://www.astm.org/Standards/F2696.htm http://www.faa.gov/training_testing/training/air_training_program/job_aids/media/EWiS_job-aid_2.0_Printable.pdf http://www.iasa.com.au/folders/Safety_issues/Aircraft_Wire/index.htm

Avionics News April 2012

Table of Contents for the Digital Edition of Avionics News April 2012