How to Troubleshoot Aircraft Alternators and Generators?

An aircraft alternator or generator is the electrical powerhouse of the vehicle, serving to produce the electrical power needed for flight instruments, lighting fixtures, radios, and other equipment that needs electrical power to operate. Due to the role that alternators and generators play in regard to flight capabilities and safety, it is crucial that they are well inspected when issues arise. In this blog, we will discuss some of the common methods for troubleshooting alternators and generators so that you can ensure the continued operability of your equipment.

Alternator Troubleshooting

When the aviation alternator runs into issues, many mechanics will test various processes to narrow down the problem. With a hacksaw blade and a digital multimeter, one can perform many important checks. While the alternator is not running, the circuit will be energized so that an electromagnet is formed. As the hacksaw blade is pressed against the housing of the assembly, the metal part of the blade should begin tugging magnetically. If this occurs, then it is indicative that the alternator is able to produce a magnetic field. While a magnetic field is a good sign, it does not mean that the alternator can hold a load. As such, the engine will need to be run with a typical load while verifying voltage levels. If there is little to no tug present, then components such as the voltage regulator, switches, breakers, conductors, and connections should all be looked over while conducting other tests.

Once the voltage regulator has been inspected, then the input and output voltage should be verified. For proper functionality, the input voltage should be a close match to the bus voltage. With drops that surpass 0.5 volts, an issue may be occurring upstream from the regulator. If it is beyond 1.5 volts, on the other hand, then the voltage regulator may be facing an internal fault or ground issue. Beyond such tests, one should follow a standard troubleshooting flow-chart to guarantee that all potential issues have been tested for.

Generator Troubleshooting

With a DC charging system, it is important to know that such devices may have either a type “A” or type “B” circuit. As both types differ in their troubleshooting methods, it is important to be aware of which type you may have. With an aircraft generator that has an “A” type circuit, the voltage regulator will manage the amount of ground that is placed on the field circuit. Aviation alternators, on the other hand, typically have a “B” circuit. When the generator faces various issues, a technician will conduct what is known as a full field test. To begin, full battery or full grounding will be used to jump the generator, surpassing the regulator so that the device may charge at full output as it rotates.

Following similar steps to test bench procedures, the generator will be rotated by the aircraft engine. As the system voltage will be raised during this operation, all electrical devices should be shut off for their protection. During the full field test, the armature and field wire of the generator will be removed with their ends taped, and a jumper will be connected from the airframe ground to the field post. With a multimeter, a connection is made from the armature post to airframe ground before the engine is started and brought up to speed. If the voltage on the armature post follows alongside throttle, then the aircraft generator should be considered okay. Additionally, the two wires that extend from the generator to the voltage regulator should be inspected, and battery voltage should range from 12 to 24 volts to ensure the health of the voltage regulator itself.


Regardless of whether one operates an AC generator, alternator, or a similar system, such equipment should be well maintained to guarantee the use of the electrical system. Without power, pilots may be unable to properly track crucial flight data, communicate outside of the aircraft, provide services to passengers, and more. As a result, any issue should be remedied as soon as possible, and all aging or damaged components must be replaced or repaired before the next flight operation. If you find yourself in need of various aircraft generator and alternator components for maintenance, look no further than Aerospace Buying.

Aerospace Buying is an online distributor of aircraft parts, and we are your sourcing solution for exciter field assembly components, voltage regulator products, and so much more. Take the time to explore our ever expanding catalogs at your leisure, and our team is always on standby to assist you through the purchasing process as needed. If you find yourself facing a time constraint or AOG situation, we expedite shipping on all domestic and international orders with the use of our robust supply chain network. Experience the revolution of part procurement with Aerospace Buying today when you get in contact with one of our representatives.

  1. Posted on November 10, 2021
  2. electronics components

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