Is it Better to Overhaul, Repair, or Replace Your Aircraft Starter Generator?

The Aircraft Starter Generator is an essential component of the aircraft’s power system.

A starter generator on an aircraft combines the functions of a starter motor and a generator. Initially, it acts as a starter motor to crank the engine by converting electrical energy from the aircraft’s battery into mechanical energy, starting the engine. Once the engine is running, it switches to generator mode, converting mechanical energy from the engine into electrical energy, which is then used to power the aircraft’s systems and recharge the battery.

One of the most challenging decisions for airplane owners and operators is whether to overhaul, repair, or replace their starter generator. This decision depends on factors such as the unit’s operating hours, the OEM (original equipment manufacturer) recommendations for brush change and TBO (time between overhauls), the generator’s condition, and the associated costs.

Common Problems That Affect Aircraft Starter Generators

Starter generators can develop several problems over time, most commonly wear and tear or the failure of certain components. Some of the most typical difficulties are:

Normal, Excessive, and Abnormal Wear: Armature commutator and carbon brush wear are the most prevalent.

Electrical Failures: Like any other electrical component, the starter generator might fail due to worn brushes, wiring difficulties, overheating, short circuits in the stator or armature, or bad connections. These electrical problems might hinder the generator from efficiently producing or delivering proper current power.

Failure of Mechanical Parts: The starter generator’s mechanical parts are prone to wear, including bearings, endbell, anti-drive endbell, and drive shaft. After time, they might degrade, causing trouble in performance and/or complete catastrophic failure.

Overheating: If the starter generators are heavily cycled (excessive starts), subjected to heavy loads, inadequate battery voltage, and/or have not been adequately maintained, they can overheat. Overheating might lead to internal component damage and eventually cause the starter generator to fail to operate.

Corrosion and Contamination: The aircraft runs in various environments, which might result in corrosion or contamination of the starter generator. Moisture, carbon brush dust, bird strikes, and other contaminants might reduce the generator’s efficiency and performance.

Why Overhaul an Aircraft Starter Generator?

• Cost-Effectiveness.

One key reason for having an aircraft starter generator overhauled is to save money. Overhauling a starting generator is often more economical than purchasing and installing a new unit, making it a better financial decision for most aircraft owners. This cost-effectiveness provides economic security, especially for those looking to reduce operational costs while ensuring maximum aircraft performance.

If the generator is in relatively good condition and only needs replacement of standard components, overhauling may be a more cost-effective option. This is especially useful for aircraft owners or operators who want to reduce operational costs while ensuring maximum aircraft performance without facing the high initial expenditure of a new generator.

• Restoring Performance and Reliability.

Overhauling a starting generator restores its performance to its original specs. During an overhaul, worn or degraded components, such as brushes, bearings, armatures, and stators, are replaced or repaired. This improves the generator’s efficiency, dependability, and general performance. Maintaining the reliability of an aircraft’s starter generator is crucial for ensuring smooth engine starts and good electrical system operation while in flight.

• Regulatory Compliance.

Aircraft maintenance and repair, including overhauls, are subject to tight restrictions and oversight by aviation authorities. Overhauling and repairing the starter generator ensures that it meets flight-related safety and performance standards. Operators may retain regulatory compliance by choosing a repair or overhaul while assuring the aircraft’s and its passengers’ safety. From a compliance perspective, purchasing a brand-new unit ensures you will also comply, but at a much higher cost.

Why Repair an Aircraft Starter Generator?

• Cost-Effectiveness.

If financial constraints were not an issue, overhauling a starter generator would always be preferable. However, in some cases, this may not be necessary.  If the generator is in good condition and only needs minor repairs or parts replaced, repairing it may be the best option. Examples of when a repair may be the best choice are when the driveshaft dampener assembly shows signs of wear, the brush(s) won’t make TBO, and other minor issues.  However, all these factors must be weighed by what the TBO is.  If the unit has 40% or less time before requiring an overhaul, it may make sense to have it overhauled.

Why Replace an Aircraft Starter Generator?

While overhauling an aviation starter generator is often a cost-effective solution, there are times when replacement is the better option. Replacement is commonly advised when:

Severe Damage: Replacement may be better if the starter generator is extensively mechanically or electrically damaged. The stator or armature, among other critical components, can become so severely damaged that overhauling may no longer be feasible. 

Obsolete Parts: Over time, some starting generator components may be discontinued or are not readily available.  In these cases, replacing the entire unit can be a better option.

Repair/Overhaul Costs Exceed the Cost of a New or a Replacement Overhauled Stater Generator: In some situations, overhauling a starter generator might be beyond economical repair (BER), so buying a new or replacement overhauled unit may be a better choice.  An example of this may happen is when there is a catastrophic bearing failure where the armature and stator are non-repairable.

Wrap Up: 

Several factors must be considered when deciding whether to overhaul, repair, or replace an aircraft starter generator. Overhauling or repairing may be a cost-efficient option if the generator is still in good operational condition; all that’s needed is some components must be replaced or repaired. However, it may be preferred if the generator has suffered significant damage, its parts are obsolete, or repair costs are even higher than those for a replacement unit.

If you’re unsure whether it’s time to overhaul, repair, or replace your aircraft starter generator, aircraft maintenance near me? Well, it’s time to speak with an expert. NAASCO, known as an aircraft component overhaul, repair, and manufacturing facility, specializes in skilled aircraft component repair or overhaul and provides detailed diagnoses and recommendations for your starter generator and other essential components. 

Schedule time with us today to keep your aircraft starter generator operating smoothly and safely. Allow our expert team to ensure that your aircraft components perform at their peak every time.