Ignition And Electrical Systems

By visually inspecting the amount of wear groove remaining on the brushes.

Both commutator and brushes should be inspected for wear beyond operational limits.

Generally, both field and Armature receive current for operation in the start mode.

A ground power unit, (GPU), an on-board auxiliary power unit (APU), compressor bleed air from an already running engine.

A specific number of degrees (as determined by the manufacturer) before the piston reaches top dead center on the compression stroke.

To improve combustion efficiency, and provide redundancy for safety.

For an engine to run properly, the spark plug in a cylinder has to fire at a specific time. To produce the required energy for the spark at the required time, the magneto must be in the E gap position, the breaker points must start to open, and the distributor must be electrically aligned with the particular cylinder. If any of these requirements are not correctly adjusted, the engine will run rough or may not run at all. When preparing a magneto for installation, First the internal timing must be correctly adjusted, then the magneto-to-engine timing is adjusted.

It produces a high-voltage that forces a spark to arc across a spark plug gap.

A permanent multipole rotating magnet, soft iron core, and Pole shoes.

Magnet, primary and secondary.

It is eight point a few degrees beyond the neutral position of a rotating magnet where the maximum magnetic field stress exists.

A capacitor.

In the rotation cycle, when the magnetic rotor is in the E-gap position, the primary points open, which interrupts the current flow in the primary circuit causing a high rate of flux change in the core, and inducing a pulse of high-voltage in the secondary coil.

The P-lead connects the ignition switch to the primary circuit of the magneto. When the ignition switch is turned off, the P-leads on both magnetos are grounded. When the ignition switch is turned to the “LEFT” position, the right magneto is grounded, so that only the left magneto operates, and visa versa.

It is used for both internal magneto timing and magneto-to-engine timing, and indicates the exact instant the magneto points open.

Because the high energy sparks they produce clean off any deposits on the firing end.

A duty cycle allows the operation of the ignition system for a given amount of time, and is then followed by a minimum specified cooling down period.

Ignition exciters, high tension leads, igniters.

When connected to the battery positive lead, the ammeter indicates whether the battery is charging or discharging. When connected to the generator output lead, it indicates the current produced by the generator, or electrical system load.

The generators of paralleled.

On the data plate attached to the generator.

By varying the field current strength.

The three phase alternator.

By regulating the voltage output of the DC exciter.

The frequency of the alternator output.

Constant speed drives, integrated drive generators, and variable speed constant frequency (VSCF) power systems.

The Armature, field, brushes and frame assembly.

An electric motor, reduction gears, and an automatic engaging and disengaging mechanism.

Series, shunt and compound.

A series wound motor is commonly used because it has a high starting torque under heavy load conditions.

It operates first as a starter, then as a generator once the engine is running.

A dirty or worn starter commutator.

When they run close to high temperature areas such as exhaust stacks were eating ducts.

The American wire gauge (AWG).

By a number gauge size. The smaller wires are represented by larger numbers. The smallest size wire normally used in Aircraft is 22 gauge.

Not over 1/2 inch.

To provide a current return path for electrical accessories, and to prevent static discharge.