Defects in Electrical System Components
To further simplify the location of electrical system faults it is thought desirable to outline the defects that can be present in the various parts of the individual devices comprising the ignition system. If an airplane engine is provided with magneto ignition solely, as most engines are at the present time, no attention need be paid to such items as storage or dry batteries, timer or induction coil. There seems to be some development in the direction of battery ignition so it has been considered desirable to include components of these systems as well as the almost universally used magneto group. Spark-plugs, wiring and switches are needed with either system.
| SPARK-PLUGS | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Insulation cracked. | Plug inoperative. | New insulation. | |
| Insulation oil soaked. | Cylinder misfires. | Clean. | |
| Carbon deposits. | Short circuited spark. | Remove. | |
| Insulator loose. | Cylinder misfires. | Tighten. | |
| Gasket broken. | Gas leaks by. | New gasket. | |
| Electrode loose on shell. | Cylinder misfires. | Tighten. | |
| Wire loose in insulator. | Cylinder misfires. | Tighten. | |
| Air gap too close. | Short circuits spark. | Set correctly. | |
| Air gap too wide. | Spark will not jump. | Set points 1⁄32′′ apart. | |
| Loose terminal. | Cylinder may misfire. | Tighten. | |
| Plug loose in cylinder. | Gas leaks. | Tighten. | |
| Mica insulation oil soaked. | Short circuits spark. | Replace. | |
| MAGNETO | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Dirty oil in distributor. | Engine misfires. | Clean. | |
| Metal dust in distributor. | Engine misfires. | Clean. | |
| Brushes not making contact. | Current cannot pass. | Strengthen spring. | |
| Distributor segments worn. | Engine misfires. | Secure even bearing. | |
| Collecting brush broken. | Engine misfires. | New brush. | |
| Distributing brush broken. | Engine misfires. | New brush. | |
| Oil soaked winding. | Engine misfires. | Clean. | |
| Magnets loose on pole pieces. | Engine misfires. | Tighten screws. | |
| Armature rubs. | Engine misfires. | Repair bearings. | |
| Bearings worn. | Noisy. | Replace. | |
| Magnets weak. | Weak spark. | Recharge. | |
| Contact breaker points pitted. | Engine misfires. | Clean. | |
| Breaker points out of adjustment. | Engine misfires. | Reset. | |
| Defective winding (rare). | No spark. | Replace. | |
| Punctured condenser (rare). | Weak or no spark. | Replace. | |
| Driving gear loose. | Noise. | Tighten. | |
| Magneto armature out of time. | Spark will not fire charge. | Retime. | |
| Magneto loose on base. | Misfiring and noisy. | Tighten. | |
| Contact breaker cam worn. | Misfiring. | Replace. | |
| Fibre shoe or rolls worn (Bosch). | Misfiring. | Replace. | |
| Fibre bushing binding in contact lever (Bosch). | Misfiring. | Ream slightly. | |
| Contact lever return spring broken. | No spark. | Replace. | |
| Contact lever return spring weak. | Misfiring. | Replace. | |
| Ground wire grounded. | No spark. | Insulate. | |
| Ground wire broken. | Engine will not stop. | Connect up. | |
| Safety spark gap dirty. | No spark. | Clean. | |
| Fused metal in spark gap. | No spark. | Remove. | |
| Safety spark gap points too close. | Misfiring. | Set properly. | |
| Loose distributor terminals. | Misfiring. | Tighten. | |
| Contact breaker sticks. | No spark control. | Remove and clean bearings. | |
| Magneto switch short-circuited. | No spark. | Insulate. | |
| Magneto switch open circuit. | No engine stop. | Restore contact. | |
| STORAGE BATTERY | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Electrolyte low. | Weak current. | Replenish with distilled water. | |
| Loose terminals. | Misfiring. | Tighten. | |
| Sulphated terminals. | Misfiring. | Clean thoroughly and coat with vaseline. | |
| Battery discharged. | Misfiring or no spark. | New charge. | |
| Electrolyte weak. | Weak current. | Bring to proper specific gravity. | |
| Plates sulphated. | Poor capacity. | Special slow charge. | |
| Sediment or mud in bottom. | Weak current. | Clean out. | |
| Active material loose in grids. | Poor capacity. | New plates. | |
| Moisture or acid on top of cells. | Shorts terminals. | Remove. | |
| Plugged vent cap. | Buckles cell jars. | Make vent hole. | |
| Cracked vent cap. | Acid spills out. | New cap. | |
| Cracked cell jar. | Electrolyte runs out. | New jar. | |
| DRY CELL BATTERY | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Broken wires. | No current. | New wires. | |
| Loose terminals. | Misfiring. | Tighten. | |
| Weak cell (7 amperes or less). | Misfiring. | New cells. | |
| Cells in contact. | Short circuit. | Separate and insulate. | |
| Water in battery box. | Short circuit. | Dry out. | |
| TIMER | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Contact segments worn or pitted. | Misfiring. | Grind down smooth. | |
| Platinum points pitted. | Misfiring. | Smooth with oil stone. | |
| Dirty oil or metal dust in interior. | Misfiring. | Clean out. | |
| Worn bearing. | Misfiring. | Replace. | |
| Loose terminals. | Misfiring. | Tighten. | |
| Worn revolving contact brush. | Misfiring. | Replace. | |
| Out of time. | Irregular spark. | Reset. | |
| INDUCTION COIL | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Loose terminals. | Misfiring. | Tighten. | |
| Broken connections. | No spark. | Make new joints. | |
| Vibrators out of adjustment. | Misfiring. | Readjust. | |
| Vibrator points pitted. | Misfiring. | Clean. | |
| Defective condenser | } rare. | No spark. | Send to maker for repairs. |
| Defective winding | |||
| Poor contact at switch. | Misfiring. | Tighten. | |
| Broken internal wiring. | No spark. | Replace. | |
| Poor coil unit. | One cylinder affected. | Replace. | |
| WIRING | |||
| DEFECT | TROUBLE CAUSED | REMEDY | |
| Loose terminals anywhere. | Misfiring. | Tighten. | |
| Broken plug wire. | One cylinder will not fire. | Replace. | |
| Broken timer wire. | One coil will not buzz. | Replace. | |
| Broken main battery wire. | } No spark. | Replace. | |
| Broken battery ground wire. | |||
| Broken magneto ground wire. | Engine will not stop. | Replace. | |
| Chafed insulation anywhere. | } Misfiring. | Insulate. | |
| Short circuit anywhere. | |||