Engine System

 GENERAL

Most aircraft engines are started by a device

called a starter. A starter is a mechanism capable

of developing large amounts of mechanical energy that can be applied to an engine, causing it

to rotate.

In the early stages of aircraft development, relatively low-powered engines were started by pulling the propeller through a part of a revolution by

hand. Some difficulty was often experienced in cold

weather starting when lubricating oil temperatures

were near the congealing point. In addition, the

magneto systems delivered a weak starting spark at

the very low cranking speeds. This was often compensated for by providing a hot spark, using such

ignition system devices as the booster coil, induction

vibrator, or impulse coupling.

Some small, low-powered aircraft which use handcranking of the propeller for starting are still being

operated. For general instructions on starting this

type of aircraft, refer to the Airframe and Powerplant Mechanics General Handbook, AC 65-9,

Chapter 11.

RECIPROCATING ENGINE STARTING SYSTEMS

Throughout the development of the aircraft reciprocating engine from the earliest use of starting

systems to the present, a number of different starter

systems have been used. The most common of

the.. ce are:

(1) Cartridge starter. (Wot in common use.)

(2) Hand inertia starter. (Not in common use.)

(3) Electric inertia starter. (Not in common

use.)

(4,) Combination inertia starter. (Not in common use.)

15) Direct-cranking electric starter.

CHAPTER 5

ENGINE STARTING SYSTEMS

Most reciprocating engine starters are of the

direct-cranking electric type. A few older model

aircraft are still equipped with one of the types of

inertia starters, and in very rare instances an

example of the hand cranking, hand inertia. or

cartridge starter may be found. Thus, only a brief

description of these starting systems is included in

this section.

Inertia Starters

There are three general types of inertia starters:

(1) Hand inertia starters. (2) electric inertia

starters, and (3) combination hand and electric

inertia starters.

The operation of all types of inertia starters depends on the kinetic energy stored in a rapidly

rotating flywheel for cranking ability. (Kinetic

energy is energy possessed by a body by virtue of

its state of motion, which may be movement alon~

a line or spinning action.) In thc inertia starter.

energy is stored slowly during an energizing process

by a manual hand crank or electrically with a

small motor. The flywheel and movable gears of

a combination hand electric inertia starter are

shown in figure 5-1. The electrical circuit for an

electric inertia starter is shown in figure 5-2.

During the energizing of the starter. all movablc

parts within it, including the flywheel, are set in

motion. After the starter has been fully energized.

it is engaged to the crankshaft of the engine by a

cable pulled manually or by a meshing solenoid

which is energized electrically. When the starter

is engaged or meshed, flywheel energy is transferred to the engine through sets of reduction

gears and a torque overload release clutch (sec

figure 5-3).

Direct-Cranking Electric Starter

The most widely used starting system on all

types of reciprocating engines utilizes the directcranking electric starter. This type of starter provides instant and continual cranking when energy