AIRCRAFT ELECTRICAL SYSTEM
(RECIPROCATING ENGINE)
INTRODUCTION
Virtually all aircraft contain some form of an electrical system. The most basic aircraft must produce electricity for operation of the
engine’s ignition system. Modern aircraft have complex electrical systems that control almost every aspect of flight. In general,
electrical systems can be divided into different categories according to the function of the system. Common systems include lighting,
engine starting, and power generation.
Definitions
1. "Inspect" means to examine by sight and touch.
2. "Check" means to verify proper operation.
3. "Troubleshoot" means to analyze and identify malfunctions.
4. "Service" means to perform functions that assure continued operation.
5. "Repair" means to correct a defective condition. Repair of an airframe or powerplant system includes component
replacement and adjustment, but not component repair.
6. "Overhaul" means to disassemble, inspect, repair as necessary, and check.
What is Electricity?
A form of energy associated with stationary or moving electrons, ions, or other charged particles.
Electricity provides electrical power throughout the aircraft
Most aircraft are equipped with either a 14- or a 28-volt direct current electrical system. A basic aircraft electrical system consists of
the following components:
Battery
Alternator/Generator
Master (Battery switch/ Alternator switch)
Bus bar, Fuses, and Circuit breakers
Voltage regulator
Ammeter/ Loadmeter
Associated electrical wiring
BATTERY
Stores electrical energy
Provides electrical power to start the engine
Stores a limited supply of backup power if alternator or generator fails
Recharges when engine is running (turning Alt/Gen)
MASTER /BATTERY CONTACTOR
Electrical Switch
Battery contactor relays a large electrical current from origination source (Battery or Auxiliary Power Unit –APU) to Starter
Contactor and to the bus bar.
STARTER CONTACTOR
Electrical Switch
Starter Contactor relays a large electrical current from origination source (Battery or Auxiliary Power Unit –APU) to rotate
Starter Motor
MASTER SWITCH
Controls entire electrical system except for Magneto Ignition system, including interior/exterior lights, radios, fuel gauges,
pumps, -and –engine starter motor
Some airplanes equipped with battery switch and alternator switch (split switch)
Alternator switch (ALT) disconnects alternator from electrical system in case of alternator failure (ALT=OFF)
AMMETER
Monitors the performance of the electrical system
Shows if the alternator/ generator is producing an adequate supply of electrical power
1
(RECIPROCATING ENGINE)
INTRODUCTION
Virtually all aircraft contain some form of an electrical system. The most basic aircraft must produce electricity for operation of the
engine’s ignition system. Modern aircraft have complex electrical systems that control almost every aspect of flight. In general,
electrical systems can be divided into different categories according to the function of the system. Common systems include lighting,
engine starting, and power generation.
Definitions
1. "Inspect" means to examine by sight and touch.
2. "Check" means to verify proper operation.
3. "Troubleshoot" means to analyze and identify malfunctions.
4. "Service" means to perform functions that assure continued operation.
5. "Repair" means to correct a defective condition. Repair of an airframe or powerplant system includes component
replacement and adjustment, but not component repair.
6. "Overhaul" means to disassemble, inspect, repair as necessary, and check.
What is Electricity?
A form of energy associated with stationary or moving electrons, ions, or other charged particles.
Electricity provides electrical power throughout the aircraft
Most aircraft are equipped with either a 14- or a 28-volt direct current electrical system. A basic aircraft electrical system consists of
the following components:
Battery
Alternator/Generator
Master (Battery switch/ Alternator switch)
Bus bar, Fuses, and Circuit breakers
Voltage regulator
Ammeter/ Loadmeter
Associated electrical wiring
BATTERY
Stores electrical energy
Provides electrical power to start the engine
Stores a limited supply of backup power if alternator or generator fails
Recharges when engine is running (turning Alt/Gen)
MASTER /BATTERY CONTACTOR
Electrical Switch
Battery contactor relays a large electrical current from origination source (Battery or Auxiliary Power Unit –APU) to Starter
Contactor and to the bus bar.
STARTER CONTACTOR
Electrical Switch
Starter Contactor relays a large electrical current from origination source (Battery or Auxiliary Power Unit –APU) to rotate
Starter Motor
MASTER SWITCH
Controls entire electrical system except for Magneto Ignition system, including interior/exterior lights, radios, fuel gauges,
pumps, -and –engine starter motor
Some airplanes equipped with battery switch and alternator switch (split switch)
Alternator switch (ALT) disconnects alternator from electrical system in case of alternator failure (ALT=OFF)
AMMETER
Monitors the performance of the electrical system
Shows if the alternator/ generator is producing an adequate supply of electrical power
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