Most starting system maintenance practices include replacing the starter motor brushes and brush springs, cleaning dirty commutators, and turning down burned or out-of-round starter commutators. As a rule, starter brushes should be replaced when worn down to approximately one-half the original length. Brush spring tension should be sufficient to give brushes a good firm contact with the commutator. Brush leads should be unbroken and lead terminal screws tight.
A glazed or dirty starter commutator can be cleaned by holding a strip of double-0 sandpaper or a brush seating stone against the commutator as it is turned. The sandpaper or stone should be moved back and forth across the commutator to avoid wearing a groove. Emery paper or carborundum should never be used for this purpose because of their possible shorting action.
Roughness, out-of-roundness, or high-mica conditions are reasons for turning down the commutator. In the case of a high-mica condition, the mica should be undercut after the turning operation is accomplished.
The drive gear should be checked for wear along with the ring gear. The electrical connections should be checked for looseness and corrosion. Also, check the security of the mounting of the housing of the starter.
Troubleshooting Small Aircraft Starting Systems
The troubleshooting procedures listed in Figure are typical of those used to isolate malfunctions in small aircraft starting systems.| Probable Cause | Isolation Procedure | Remedy | |
|---|---|---|---|
| Starter will not operate | Defective master switch or circuit | Check master circuit | Repair circuit |
| Defective starter switch or switch circuit | Check switch circuit continuity | Replace switch or wires | |
| Starter lever does not activate switch | Check starter lever adjustment | Adjust starter lever in accordance with manufacturer’s instructions | |
| Defective starter | Check through items above. If another cause is not apparent, starter is defective | Remove and repair or replace starter | |
| Starter motor runs, but does not turn crankshaft | Starter lever adjusted to activate switch without engaging pinion with crankshaft gear | Check starter lever adjustment | Adjust starter lever in accordance with manufacturer’s instructions |
| Defective overrunning clutch or drive | Remove starter and check starter drive and overrunning clutch | Replace defective parts | |
| Damaged starter pinion gear or crankshaft gear | Remove and check pinion gear and crankshaft gear | Replace defective parts | |
| Starter drags | Low battery | Check battery | Charge or replace battery |
| Starter switch or relay contacts burned or dirty | Check contacts | Replace with serviceable unit | |
| Defective starter | Check starter brushes, brush spring tension for solder thrown on brush cover | Repair or replace starter | |
| Starter excessively noisy | Dirty, worn commutator | Clean and check visually | Turn down commutator |
| Worn starter pinion | Remove and examine pinion | Replace starter drive | |
| Worn or broken teeth on crankshaft gears | Remove starter and turn over engine by hand to examine crankshaft gear | Replace crankshaft gear | |
Small aircraft troubleshooting procedures