Aircraft EWIS Wiring, Components and Inspection Procedures

EWIS: Definition and Components

EWIS

EWIS refers to wires, wiring devices, and combinations of these. EWIS includes the termination devices installed in any area of the aircraft whose purpose is the transmission of electrical energy between two or more termination points. These EWIS wires and associated components are treated as an airplane system.

It is important to know that EWIS doesn't include avionics, portable electrical devices, electrical equipment, or fiber optics. EWIS includes the following:

• Wires and cables
• Bus bars
• Termination points and electrical devices, including those on relays, interrupters, switches, and circuit breakers
• Connectors and connector accessories
• Electrical grounding and bonding devices
• Electrical splices
• Materials used to provide additional protection for wires, including wire insulation, wire sleeving, and conduits that have electrical termination for the purpose of bonding
• Shields or braids
• Pressure seals
• Labels or other means of identification
• Cable tie devices
• EWIS components inside shelves, racks, panels, junction boxes, distribution panels, and the backplane of equipment racks, including, but not limited to, circuit board backplanes, wire integration units, and external wiring of equipment

EWIS Inspection

Many simple corrections to EWIS can be made to reduce degradation and provide a longer functional life. Inspection of installations, repairs, and general appearance goes a long way toward solving EWIS problems.

There are three basic EWIS inspections:

• The first is a general visual inspection (GVI).
• The second is a stand-alone GVI.
• The third is a detailed inspection (DET).

EWIS inspection focus areas include:

• Connectors
• Clamping points
• Terminations
• Backshells
• Damaged sleeving and conduits
• Grounding points

Following manufacturer-specified procedures for inspections ensures that up-to-date EWIS concerns and procedures are addressed.

Inspection Locations Requiring Attention

Some EWIS inspection locations are listed below. Available data shows that these areas should receive special attention in an operator's EWIS inspection program:

• Wings
• Engine, pylon, and nacelle area
• APU
• Landing gear and wheel wells
• Electrical panels and line replaceable units (LRUs)
• Cargo bay — underfloor
• Power feeders
• Batteries
• Under galleys and lavatories
• Access panels
• Surfaces, doors, and controls