SAFETY PRACTICES AND ZONING
AIRCRAFT ZONING AND ELECTRICAL SAFETY
General
For work on the electrical system it is necessary:
- to know and obey the standard safety practices
- to have a good knowledge of the electrical standard practices
- to have a good knowledge of requirements (processes, WARNINGS, CAUTIONS etc.) before you start the work.
This is necessary to prevent injury to persons and/or damage to equipment.
Electrical Safety Practices
Before you start work, open, safety and tag the circuit breaker(s) related to the system/equipment to prevent the supply of electrical power to the system/equipment during the maintenance work. This prevents the risk of:
- Electric shocks that can occur if you touch energized wiring connections, terminals, etc.
- Short circuits that can occur if metal tools or parts accidentally touch energized wiring, terminals, contacts, etc.
Some circuit breakers (A320 family only) have a red threaded bush. This bush prevents reset of the circuit breaker in flight (the crew cannot pull it). If, for maintenance safety reasons, it is necessary to open such a circuit breaker, you can remove the red threaded bush with a standard wrench.
Tools
- Never use electric tools which deliver an energy of more than 0.02 millijoule in fuel tanks or in areas where there are flammable vapors.
- Never use heat-generating tools in the fuel tanks or in areas where there are flammable vapors.
- Use only crimp-type contacts, terminals, splices, sleeves (non-heat shrinkable sleeves) in these areas.
Zoning Method
The system consists of Major Zones, Major Sub-Zones and Zones. Each Zone is based on a three-figure number. The zones, where possible, are defined by actual physical boundaries such as wing spars, major bulkheads, cabin floor, control surface boundaries, skin, etc.
(1) Major Zone
100 Lower part of the fuselage to rear pressure bulkhead
200 Upper part of fuselage to rear pressure bulkhead
300 Empennage
400 Powerplants and pylons and nacelles
500 Left Wing
600 Right Wing
700 Landing Gear and Landing Gear Doors
800 Doors
(2) Major Sub-Zones
These are divisions of the Major Zones, for example 100 is divided into 110, 120, 130, 140, etc. The Major Sub-Zone/numbering sequence for the fuselage must run from front to rear. In case of double deck passenger fuselage, the numbering for the main deck can be 220, 230, 240 and 250, and for the upper deck 260, 270, 280 and 290. The numbering for the cockpit must be 210.
(3) Zones
These are divisions of Major Sub-Zones, for example 120 is divided into 121, 122, 123. The sequence of Zones for the fuselage main and upper decks (if any) must run from front to rear and away from the floor line. For example: - Left/Right Main Deck 231/232 - Left/Right Main Deck Ceiling (if required) 233/234 - Left/Right Upper Deck 271/272 - Left/Right Upper Deck Ceiling (if required) 273/274
(4) Left or Right Zones
A single figure indicates, where applicable, left or right hand zones. An odd number indicates a left-hand or center zone and an even number indicates a right-hand zone
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