Three Modifications And One Troubleshooting Tip To Improve Aircraft Starter Generator Reliability

March 2024

I’m sure you’ve often asked yourself why your starter generator doesn’t make it the TBO (Time Between Overhaul). Although I could provide you with several answers, it would be better if I could tell you how to get your starter generator to make it to TBO.

There are many starter generators from many manufacturers, all with one thing in common: they all need modifications to improve their lives and reliability.

Three popular starter generator modifications include the following:

• Cooling the unit by increasing airflow
• Ceramic bearings to reduce the friction caused by heating steel bearings
• Longer-life brushes made from a hardened carbon material.

These modifications are meant to increase the life and time between unit failures.

Troubleshooting: Is it the starter generator or the GCU?

Starter generator squawks can be complicated and often lead to frustrations as you struggle to determine whether the generator or GCU (general control unit) is at fault. Here’s a simple troubleshooting test to help narrow down the fault.

Using a multimeter, measure the resistance between the starter generator lead attach lugs and the generator case. With the leads removed, the resistance between the lugs and the case should be more than 50k ohms.

A less than 50k ohms reading indicates carbon dust build-up from the brushes, which can lead to spurious GCU faults and eventual total failure. If resistance is less than 50k ohms, we highly recommend a starter generator tear-down and inspection.

Contact your Duncan Aviation Customer Account Reps to schedule service for your starter generator.

To get the full life out of your starter generator and alleviate unscheduled downtime, contact Duncan Aviation Accessory Tech Reps.