Electrical systems and avionics — the aircraft's nervous system.
From flight management systems to EWIS and bonding
If the aircraft structure and engines are the body, the electrical systems and avionics systems are the nervous system. From communication and navigation equipment to autopilot, instruments and flight management systems, almost everything on a modern aircraft is electronically controlled and monitored — and all that equipment is connected by kilometres of wiring that must function flawlessly for decades under vibration, temperature fluctuations and moisture.
§From compass to flight management system
Avionics Covers Everything from the Most Basic Flight Instruments to Advanced Systems that Calculate the Most Fuel-Economical Route, Keep the Plane on Course via Autopilot and Alert the Crew to Errors in Real Time. As a B2 Aircraft Technician (Electronics) You Work on Testing, Troubleshooting and Replacing These Systems According to the Aircraft's Maintenance Manuals, Often With Specialised Test Equipment that Simulates Signals from Other Parts of the Aircraft.
§EWIS—the aircraft's wiring system as its own system
The electrical wiring interconnection system, called today collectively EWIS (Electrical Wiring Interconnection System), is treated as a separate system with its own requirements for inspection and maintenance. Investigations of aircraft accidents with fire and explosions on board in the 1990s pointed to worn or incorrectly installed wiring as a contributing cause, which led to EWIS being formalized as its own certification area in the American regulations (FAR 25 Subpart H) and the corresponding European CS-25, with requirements for separation from flammable systems, protection against sharp edges and access to inspection.
§What you look for in an EWIS inspection
- 01Wear and chafing where the insulation is scraped
- 02Damage to insulation that exposes the conductor
- 03Contamination from liquid spills dust or corrosion products
- 04Overheating — discolouration or brittle insulation
- 05PLACEHOLDER_17
§Static electricity and bonding
Planes build up static electricity during flight among other things from air friction and can be hit by lightning. Therefore all metal parts are electrically connected with so-called bonding straps so current and static electricity is routed away in a controlled way instead of jumping as sparks between loose parts. As an aircraft technician you check the resistance in these connections with a special measuring instrument and compare with the limit values in the maintenance manual.
§B1 and B2 — Who Does What
The education's level reflects exactly this division: B1 aircraft technician has the main focus on mechanics, motors, and structure, while B2 aircraft technician specializes in electrical systems, instruments, and avionics. In practice the two specializations work closely together because virtually every modern aircraft component has both a mechanical and an electrical element.
§Test equipment and troubleshooting
Troubleshooting in electrical and electronic systems differs from mechanical troubleshooting because the symptom and the underlying cause are often far apart in the system. A warning lamp in the cockpit can be caused by an error in the sensor itself, in the wiring connection, in a computer processing the signal, or in the power supply to the entire circuit. Therefore, you typically work in a structured way: you start with the aircraft's built-in error reporting system (BITE — Built-In Test Equipment), which points to the most likely fault area, and move from there systematically through the circuit diagram with a multimeter, signal generator or specialized test equipment until the actual cause is isolated.
It is precisely because symptom and cause can be far apart that it is crucial that you document each step of troubleshooting — which tests you have performed and what they showed. This allows a colleague to take over in the middle of a task without having to start over and it ensures that you do not risk replacing a functioning but expensive component because you guessed your way through instead of following the troubleshooting tree systematically to the end.