The Enhanced Zonal Awareness procedure (EZAP) was introduced to the aviation industry that applies to Electrical Wire Interconnection System in 2005 was part of the FAA’s Notice of Proposed Rulemaking (NPRM) that covered new requirements for the assessments of new and existing aircraft (the final rule was enacted in 2007). This required existing fleet operators to develop plans for regular assessment and inspection of the Electrical Wire Interconnection System (EWIS).
Along with this regulation, the FAA released Advisory Circular AC 25-27 entitled “Development of Transport Category Airplane Electrical Wiring Interconnection Systems Instructions for Continued Airworthiness Using an Enhanced Zonal Analysis Procedure.” The goal of this AC is to “provide guidance for developing maintenance and inspection instructions for EWIS using an enhanced zonal analysis procedure.” Furthermore, this AC provided a better description of the type and level of analysis necessary.
If you are interested in EWIS, you may want to read Lectromec’s EWIS Failure Investigation article.
The EZAP process must cover the inspection interval and specific cleaning tasks for each zone to minimize the presence of combustible materials. There are two levels of visual inspection identified within the AC: General Visual Inspection (GVI) and Detailed Visual Inspection (DET). The GVI is described as a limited inspection within touching distance of the wiring within a zone. The goal is to identify any irregularities of the wiring bundles. The DET is an intensive wire bundle examination that may include mirrors, magnifying lens, or other tools to assist in physical examination of the wiring.
The selection of the particular inspection to be used is based on the physical, environmental, and mechanical stresses to which the wire bundle may be subjected. The AC provides a robust process to determine the frequency and type of inspection to be used. An example of this can be seen in the figure below.
While AC25-27 does not answer all questions about the EZAP, it does clarify a number of questions that one may have regarding the implementation of the program. Further details on EZAP included in this article. How this can be implemented as part of an aircraft modification is covered in this article.
If you are looking for a means to develop or adjust your EZAP for the aircraft you are modifying, Lectromec has the core competencies and experience to ease the process. Contact Lectromec to find out more.
Michael Traskos
President, Lectromec
michael.traskos@lectromec.comMichael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components.