Engine Electrical Systems Flashcards
When should the brushes in a starter motor be replaced?
When they have worn to one half of their original length.
How is the direction of rotation of a DC electric motor reversed?
Reverse the polarity of the armature or the field, but not both.
What is used as the rectifier to produce direct current in a DC generator?
Brushes and a commutator.
What is used as the rectifier to produce direct current in a DC alternator?
Six solid-state diodes.
Is a starter motor series-wound or shunt-wound?
Series wound for maximum stalled-rotor torque.
What are two ways wires can be attached to the pins in a cannon plug?
a. By soldering the wires into pots on the pins and sockets.
b. By crimping tapered pins onto the wires and inserting the pins into tapered holes in the pins and sockets.
Why is stranded wire used rather than solid wire, in most powerplant electrical systems?
Solid wire is likely to break when it is subjected to vibration.
What two things must be considered in selection of wire size when making an electrical installation in an aircraft?
The current-carrying capability of the wire, and the voltage drop caused by current flowing through the wire.
What must be done to a DC generator, after it has been overhauled, before it can produce electricity?
The field must be flashed to restore residual magnetism to the field frame so it can begin to produce current.
Why is it not necessary to flash the field of a DC alternator after it has been overhauled?
An alternator field is excited by battery current and residual voltage is not used to start the alternator producing current.
What is used to protect a wire bundle from chafing where it passes through a hole in a bulkhead or frame?
A grommet around the edges of the hole.
How are electrical wires protected where they pass through an area of high temperature?
Wires passing through these areas are insulated with high-temperature insulation, and the wires are enclosed in some type of protective conduit.
What is the minimum separation allowed between a wire bundle and a fluid line that carries combustible fluid or oxygen?
Six inches.
Which aircraft electrical circuit does not normally contain a fuse or circuit breaker?
The starter motor circuit.
What is a starter-generator?
A single, engine-mounted component that serves as a starter for starting the turbine engine. When the engine is running, the circuitry automatically shifts so it acts as a compound-wound generator.
