Reciprocating Engine Starting System Maintenance Practices

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.

Small Aircraft Troubleshooting Procedures

Probable Cause
Isolation Procedure
Starter will not operate
Defective master switch or circuit

Defective starter switch or switch circuit

Starter lever does not activate switch

Defective starter

Check master circuit.

Check switch circuit continuity.

Check starter lever adjustment.

Check through items above. If another cause is not apparent, starter is defective.
Repair circuit.

Replace switch or wires.

Adjust starter lever in accordance with manufacturer’s instructions.
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

Defective overrunning clutch or drive

Damaged starter pinion gear or crankshaft gear

Check starter lever adjustment.

Remove starter and check starter drive and overrunning clutch.

Remove and check pinion gear and crankshaft gear.
Adjust starter lever in accordance with manufacturer’s instructions.

Replace defective parts.

Replace defective parts.
Starter drags
Low battery

Starter switch or relay contacts burned or dirty

Defective starter

Check battery.

Check contacts.

Check starter brushes, brush spring tension for solder thrown on brush cover.

Charge or replace battery.

Replace with serviceable unit.

Repair or replace starter.
Starter excessively noisy
Dirty, worn commutator

Worn starter pinion

Worn or broken teeth on crankshaft gears

Clean and check visually.

Remove and examine pinion.

Remove starter and turn over engine by hand to examine crankshaft gear.
Turn down commutator.

Replace starter drive.

Replace crankshaft gear.

Small aircraft troubleshooting procedures

Reciprocating Engine Starting System Maintenance Practices