Engine Start Systems and Components piston engines Flashcards
What is the primary function of an aircraft engine starter?
The starter is an electromechanical device that develops mechanical energy to rotate the engine until it starts and can run on its own.
How did early aircraft engines, particularly reciprocating engines, get started?
Early reciprocating engines were started by manually pulling the propeller through a part of a revolution by hand.
What are the challenges associated with cold weather starting in early aircraft engines?
Cold weather caused lubricating oil to thicken near the congealing point and magneto systems to deliver weak sparks at low cranking speeds, making starting difficult.
What are the three general types of inertia starters used in aircraft?
The three general types of inertia starters are hand, electric, and combination hand and electric starters.
How does an inertia starter operate?
An inertia starter stores kinetic energy in a flywheel, which is then transferred to the engine through reduction gears and a torque overload release clutch when engaged.
What components are involved in a direct cranking electric starter?
A direct cranking electric starter typically includes an electric motor, reduction gears, an automatic engaging/disengaging mechanism, and an adjustable torque overload release clutch.
What is the purpose of the heavy-duty cables in a direct cranking electric starter system?
Heavy-duty cables are used to carry the high current flow needed to crank the engine, ranging from 100 to 350 amps depending on the required starting torque.
How does a starter motor in a direct cranking electric starter system engage the engine?
The motor’s torque is transmitted through reduction gears to a helically splined shaft that moves the starter jaw to engage the engine cranking jaw before rotating.
: What happens when the engine reaches a predetermined speed in a direct cranking electric starter system?
The starter automatically disengages when the engine reaches a predetermined speed.
What is the function of a torque-limiting clutch in a direct cranking electric starter system?
The torque-limiting clutch prevents damage by allowing the clutch plates to slip when engine torque exceeds the clutch setting.
Describe the sequence of events that occurs when the starter jaw engages the engine jaw in a direct cranking system.
The starter jaw engages the engine jaw as the motor armature reaches speed. If the engine starts, the engine jaw overruns the starter jaw, disengaging it; otherwise, the jaw remains engaged until the starter is de-energized.
What are the starter operating time limits and why are they important?
Starters should be allowed to cool after 1 minute of operation to prevent overheating and damage, with cooling times increasing after subsequent cranking periods.
What type of starter system is typically used in small reciprocating engine aircraft?
Small reciprocating engine aircraft typically use a direct cranking electric starting system, either automatically or manually engaged.
How does a manually engaged starting system work in small aircraft?
It uses a lever to shift the starter drive pinion into position and close the starter switch contacts. A return spring disengages the pinion when the engine starts.
What is the role of a worm drive gear in an automatic starting system?
The worm drive gear transfers torque from the starter motor to the clutch assembly, which then engages the engine crankshaft.
