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Electrical systems in an aircraft are groups of electrical components working individually to transmit, utilize, generate, as well as reserve electrical energy. These systems are very essential parts of every aircraft design. The various capacities, as well as complexities of aircraft electrical systems, range from a piston-powered, light, single-engine aviation aircraft to a modern and multi-engine Jet Aircraft.
It is important to note that both the most complex aircraft and simple ones share similar basic components. Every aircraft part is cataloged and assigned a National Stock Number (NSN). The electrical parts NSN can only be assigned by the National Codification Bureau (NCB).
Power Source
Every electrical system is comprised of components that can produce electricity. The kind of component used in generating electricity depends on the class of aircraft. For some, alternators are applied while others might use generators. As much as these are energy driven, they are mostly powered using an APU, an Air turbine, or hydraulic.
Generator power output range between 115-120V Alternating Current to 14V DC. This power source could be used in absence of modification or routed through rectifiers, inverters, or transformers to help change the current. The output from the generator is channeled to a couple of distribution buses.
The bus then powers the components individually. The powering is done with circuit breakers or using a fuse that would be attached during wiring. The entire process serves as a circuit protection protocol.
The aircraft batteries are also charged from the generator output. Batteries are commonly made from lithium, NICAD types, or Lead. These batteries are used to start up the aircraft as well as for cases of emergency like distribution or generator system fault.
Basic Electrical Systems/Parts
Several aircrafts with single engines do not have an installed electrical system. A self-powering magnetic ignition system is used to equip the piston. The position of the fuel reservoir enables it to gravity feed its engine – Planar Magnetics Technology.
A crank and flywheel procedure are used to start the aircraft. In the case above, an electrical system is not needed, but when it involves adding lights, navigation aids, radios, flight instruments, or electrical starters, then it becomes necessary to add electrical systems.
Mostly, the system in use would be powered by a direct current from a single channel, a battery, and a generator. A switch is made available to enable isolation of battery and alternator or generator used to be separated from the distribution bus. To take note of system failures like charging failures, an ammeter, warning light, or load meter is incorporated into the system.
Additionally, to ensure circuit protection, fuses, as well as circuit breakers, are incorporated into a bus bar. A provision for an external source of power like GPU or extra battery could be made. This would assist in starting the engine as well as providing power when the engine goes off. You can visit this website to learn more about aircraft electrical systems.
Advanced Electrical System
These kinds of systems are more sophisticated and are mostly comprised of various electrical components. They combine AC with DC channels to provide power to different parts of the aircraft. Primarily, power is generated using alternating currents along with a couple of TRU which helps to convert such current to direct current used in powering DC busses.
Secondarily, the AC volt generated from the APU is provided to be used in event of system failure and for running the aircraft when the engines are off. Hydraulic motors or RAT could also be used as a tertiary generation source incorporated to help produce redundancy in case of any other failures.
Important components of AC, as well as DC, are connected to particular buses. Meanwhile, special care is taken to ensure the provision of power to the buses in any situation of power failure. An inverter is also added to the system to power any essential alternating current bus channel directly from the battery on any account of AC power outage.
Additionally, failure monitoring and warning systems are included in the aircraft electrical system. Once an issue is identified, the particular warning signal is sent to the flight pilot. Some of these warnings could include TRU failing, bus fault, generator malfunction, as well as circuit breaker signals. The manufacturer also provides a well-detailed system isolation protocol in cases of fire outbreaks.
System Threats
Some system threats that could be faced include.
- Bus failure
- Electrical Component Failure
- Generator failure
- Electrical Fire Outbreak
Effects of System Failure
On account of system failures, the following could happen:
- Individual components could be lost.
- Components, as well as systems connected to the bus, could be lost.
- The primary power source could lose its generation capability.
- It could result in the potential destruction of the aircraft as the fire becomes uncontrollable and a constant shutdown of buses and vital components.
Defense Procedure
To reduce the possibility of a loss of electrical generation components, it is important to use multiple redundancy layers. All electrical components carry their circuit protection. This helps to prevent them from overload which could be harmful to other components if it happens.
It is important to understand that bus failures are mostly a result of power failures of the components that supply power to it, not the bus itself failing. For example, if a TRU fails, it affects the bus that is connected to it. However, if there’s an alternate source of power, the bus could be restored but this is dependent on its system design.
Furthermore, circuit breakers help to prevent system overload in any event of component failure. They also prevent potential fire outbreaks that could happen within the component. This is done by interrupting its supply of power.
If there are circuit breaker warnings, the flight crew is to comply with the company and manufacturer’s policy when considering whether to reset the circuit breaker. If there’s a second pop-up for reset CB, it should be ignored. It is important to understand that some CB reset like those involving fuel pumps are not to be reset while on the flight. You can visit https://www.linkedin.com/pulse/what-pilots-should-know-circuit-breakers-risk-resetting-anil-goyal to learn more about CB reset.
If there’s a fire outbreak from a supposed electrical source, the proper guidelines should be followed immediately. In a situation where the crew cannot identify the faulty part, an electrical isolation protocol should be carried out. The smoke elimination process may become necessary. Land as soon as possible.
Conclusion
There are various parts of an aircraft, some are most important and act individually. Every aircraft, whether complex or simple, requires basic parts. Proper care and precaution should be taken when a fault is signaled. This is to prevent the destruction of the most vital components.
