Book 3 - Engine Starting Systems

Question 1

a start requires the following:

• rotation (for air)
• fuel
• ignition

Answer 1

a start requires the following:

• rotation (for air)
• fuel
• ignition

Question 2

gas turbine engines require a _______ rate of turning than a piston engine, in order to reach self-sustaining RPM

Answer 2

gas turbine engines require a HIGHER rate of turning than a piston engine, in order to reach self-sustaining RPM

Question 3

starting a gas turbine engine is the most _________ period of the engines operation

it is the period when the engine goes from cold to hot in an exceedingly short time.

the sudden change in temperature can promote _______ shock

Answer 3

starting a gas turbine engine is the most DANGEROUS period of the engines operation

it is the period when the engine goes from cold to hot in an exceedingly short time.

the sudden change in temperature can promote THERMAL shock

Question 4

all gas turbine engines will _____ during the start cycle

Answer 4

all gas turbine engines will STALL during the start cycle

Question 5

the starter must turn the engine fast enough to obtain a minimum airflow for _______ purposes during ignition

Answer 5

the starter must turn the engine fast enough to obtain a minimum airflow for COOLING purposes during ignition

Question 6

once ignition has taken place, the combined torque from the starter and the turbine must always be enough to keep the engine __________, ultimately, to idle RPM.

should one or other fail to do this, a ____ start will be the result

should the fuel be burning at this point, a very hight turbine __________ will be apparent and the engine should be shut down immediately

a hung start can be caused due to lack of ____ flow - perhaps the HP cock has not been opened, in which case the engine will “hang on the _______”

Answer 6

once ignition has taken place, the combined torque from the starter and the turbine must always be enough to keep the engine ACCELERATING, ultimately, to idle RPM.

should one or other fail to do this, a HUNG start will be the result

should the fuel be burning at this point, a very hight turbine TEMPERATURE will be apparent and the engine should be shut down immediately

a hung start can be caused due to lack of FUEL flow - perhaps the HP cock has not been opened, in which case the engine will “hang on the STARTER”

Question 7

the start system must provide for:

• ground starting
• engine cranking
• relighting in flight or without starter assistance

Answer 7

the start system must provide for:

• ground starting
• engine cranking
• relighting in flight or without starter assistance

Question 8

hydraulic starters produce lots of ______, are fairly light and simple but need a supply of hydraulic _______ and flow. this is heavier and difficult to arrange adequately

Answer 8

hydraulic starters produce lots of TORQUE, are fairly light and simple but need a supply of hydraulic PRESSURE and flow. this is heavier and difficult to arrange adequately

Question 9

IPN (_________-_______) starters are light, simple but very __________. careless handling can give rise to fires which are impossible to extinguish

the IPN is squirted into a small _________ chamber, ignited and the resultant gases impinge on a small impulse _______ which is geared to the main engine shaft

if IPN gets on the skin, it passes straight into the _____ stream and gives rise to headaches

usually restricted to military aircraft

Answer 9

IPN (ISOPROPYL-NITRATE) starters are light, simple but very DANGEROUS. careless handling can give rise to fires which are impossible to extinguish

the IPN is squirted into a small COMBUSTION chamber, ignited and the resultant gases impinge on a small impulse TURBINE which is geared to the main engine shaft

if IPN gets on the skin, it passes straight into the BLOOD stream and gives rise to headaches

usually restricted to military aircraft

Question 10

cartridge starters use slow burning charges of various _____, depending on application. like the IPN starter, it is the resultant gases which drive a turbine connected to the main engine shaft

most engines will be fitted will have a single _______ breech but some are fitted with triple breech starters to enable multiple starts to be made

Answer 10

cartridge starters use slow burning charges of various SIZES, depending on application. like the IPN starter, it is the resultant gases which drive a turbine connected to the main engine shaft

most engines will be fitted will have a single CARTRIDGE breech but some are fitted with triple breech starters to enable multiple starts to be made

Question 11

gas turbine starters are a small gas turbine with a ____ turbine connected to the main shaft on the engine to be started

gas turbine starter is started using a small electric _____.

once engine has started, gas turbine starter is shut down.

system is fairly _____ and is restricted to military aircraft

Answer 11

gas turbine starters are a small gas turbine with a FREE turbine connected to the main shaft on the engine to be started

gas turbine starter is started using a small electric MOTOR.

once engine has started, gas turbine starter is shut down.

system is fairly HEAVY and is restricted to military aircraft

Question 12

air impingement starter is light and simple but requires specific ground support __________ to apply it.

compressed air is blown directly on to the _______ of the engine to promote initial rotation

once the engine starts a _____ supplying the external air shuts and the pipe can then be disconnected

impractical and rare

Answer 12

air impingement starter is light and simple but requires specific ground support EQUIPMENT to apply it.

compressed air is blown directly on to the TURBINE of the engine to promote initial rotation

once the engine starts a VALVE supplying the external air shuts and the pipe can then be disconnected

impractical and rare

Question 13

low pressure air turbine starters are light, simple and efficient. these are the choice of _____ large engines on commercial aircraft

Answer 13

low pressure air turbine starters are light, simple and efficient. these are the choice of MOST large engines on commercial aircraft

Question 14

electric starters are light, simple and efficient and operate from a convenient source of power like the _______ or an external supply

common on ________ engines although some fairly heavy engines have used them

Answer 14

electric starters are light, simple and efficient and operate from a convenient source of power like the BATTERY or an external supply

common on LIGHTER engines although some fairly heavy engines have used them

Question 15

the air for LP air starters is obtainable from one of the following sources:

• ___
• _____ supply
• an _______ that is already running

normally the first engine will receive its supply from the ___ and then subsequent engines will be started off of that engine

Answer 15

the air for LP air starters is obtainable from one of the following sources:

• APU
• GROUND supply
• an ENGINE that is already running

normally the first engine will receive its supply from the APU and then subsequent engines will be started off of that engine

Question 16

the ducting used to convey air from source to starter is generally _____ bore aluminium alloy, constructed to a specific design with all required bends. where a degree of flexibility is required, a _______ type coupling is used

Answer 16

the ducting used to convey air from source to starter is generally LARGE bore aluminium alloy, constructed to a specific design with all required bends. where a degree of flexibility is required, a BELLOWS type coupling is used

Question 17

there are three types of valve in the air starter systems:

• ___-return valves
• ON/___ valves
• and ________ regulating valves

Answer 17

there are three types of valve in the air starter systems:

• NON-return valves
• ON/OFF valves
• and PRESSURE regulating valves

Question 18

in pressure regulating (start control valves), the main piston will open until the downstream pressure equals that of the internal chamber, at which point the piston will hold to maintain a pressure - nominally 28 +/- _ psi, in the downstream side of the main piston

once the start system is complete, the start system will de-_______ the solenoid in the start control valve and dump the pressure in the small chamber to atmosphere. upstream pressure will now, immediately, close the main piston

Answer 18

in pressure regulating (start control valves), the main piston will open until the downstream pressure equals that of the internal chamber, at which point the piston will hold to maintain a pressure - nominally 28 +/- 2 psi, in the downstream side of the main piston

once the start system is complete, the start system will de-ENERGISE the solenoid in the start control valve and dump the pressure in the small chamber to atmosphere. upstream pressure will now, immediately, close the main piston

Question 19

in the event that the starter fails to disengage, the engine will _____ the starter; or in the event that the pressure regulating valve (start control valve) fails it may supply too much air and over-______ the starter

to prevent this fro causing excessive damage, a secondary disengaging mechanism between the reduction gear and spray clutch uses ____ type teeth.

these disengage under high torque conditions and will remain disengaged as they are held apart by a _______ washer. a belleville washer will over-_____ and remain in the new position until manually reset. this can only be achieved through disassembling the starter

Answer 19

in the event that the starter fails to disengage, the engine will DRIVE the starter; or in the event that the pressure regulating valve (start control valve) fails it may supply too much air and over-TORQUE the starter

to prevent this fro causing excessive damage, a secondary disengaging mechanism between the reduction gear and spray clutch uses ACME type teeth.

these disengage under high torque conditions and will remain disengaged as they are held apart by a BELVILLE washer. a belleville washer will over-CENTRE and remain in the new position until manually reset. this can only be achieved through disassembling the starter