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DO228 type rating > section 7: powerplant > Flashcards

section 7: powerplant Flashcards

1
Q

what is the airplane powered by?

A

2 Garrett AiResearch TPE 331-5-252 D or TPE 331-5B-252 D engines and 2 hartzell propellors

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2
Q

what kind of engine is the TPE 331-5(B)-252D?

A

lightweight single shaft turboprop engine

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3
Q

what further pressurises fuel supplied to the engine from the fuel system?

A

engine driven fuel pumps

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4
Q

what controls fuel flow to the engine fuel manifolds?

A

fuel control unit (FCU)

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5
Q

what does the automatic negative torque sensing system (NTS) do?

A

reduces propellor drag to an easily controlled level in the event of engine failure in flight

the engine also includes an ITT and torque limiting system

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6
Q

how is the engine started on the ground?

A

an electrical starter-generator which turns the rotating group through a gear train

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7
Q

what is used for ice protection in the air inlet?

A

hot engine oil from the oil sump is used in the inner part

the outer part is heated by hot bleed air from the engine

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8
Q

what kind of propellor is the Hartzell HC-B4TN- 5ML/LT 10574 propellor?

A

four bladed constant speed, full feathering and reversible pitch propellor

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9
Q

what kind of propellor does the DO228 have?

A

Hartzell HC-B4TN- 5ML/LT 10574 propellor

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10
Q

what does the type of prop blade installed depend on?

A

the ice protection installed

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11
Q

what is propellor blade angle controlled by?

A

a governor installed on the engine supplying engine oil through the propellor shaft

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12
Q

how does the governor control blade angle?

A

oil pressure decreases propellor blade angle while counterweights attached to the blade clamps plus springs and aerodynamic blade force increase blade angle towards the feathered postion

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13
Q

how is feathering accomplished?

A

opening a valve which allows the feathering spring to force the oil out of the propellor hub and back into the oil sump

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14
Q

how is unfeathring accomplished?

A

unfeathering pump

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15
Q

what holds the props in a fine pitch during ground starting?

A

spring actuated start locks

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16
Q

how can the spring actuated start locks be removed?

A

by centrifugal forces when the engine is running by moving the power levers towards reverse

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17
Q

what must the power levers be set to in order to engage the start locks on shutdown?

A

REVERSE between 60 to 30% RPM

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18
Q

below what RPM will the start locks engage?

A

approx 10%

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19
Q

how do we engage the start locks when the engine is not running?

A

activate the unfeathering pump with the POWER lever in reverse until minimum blade angle is reached

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20
Q

what 4 major components make up the power management system?

A
  • prop governor
  • prop blade angle control
  • fuel control unit (FCU)
  • engine limiting system
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21
Q

what 2 basic modes does the power management system provide?

A

beta mode and prop governing mode

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22
Q

what does beta mode do?

A

provides for pilot control of blade angle. the FCU automatically meters fuel to match engine RPM according to prop load. the power lever sets the blade angle and the USFG controls engine RPM as set by the engine speed lever.

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23
Q

when is beta mode utilised?

A

all ground operation

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24
Q

what does propellor governing mode do?

A

provides for pilot control of engine power (torque) at a selected engine speed. the prop governor controls the propellor blade angle position to automatically maintain engine speed at the pilot selected RPM. The power lever sets the fuel flow and the prop governor controls the RPM as set by the engine speed lever.

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25
Q

when is prop governing mode used?

A

all flight operations

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26
Q

what constant engine speed dos the governor provide?

A

96-100% RPM

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27
Q

how is engine oil pressure boosted and controlled into the propellor hub?

A

by the governor via the beta tube to balance the feathering forces of the prop

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28
Q

where is the beta pressure switch installed?

A

in the propellor oil control system.

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29
Q

what does the beta pressure switch do?

A

powers a blue beta light, located on the cockpit instrument panel

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30
Q

what does the blue beta light indicate?

A

indicates the propellor is operating in beta mode and extinguishes when in prop governing mode

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31
Q

is there a requirement for the beta light to be on below a high RPM setting?

A

no

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32
Q

how does the prop blade angle control/beta servo position the blade angle?

A

it holds the beta cam which provides metered oil through the beta tube

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33
Q

what does the propellor blade angle control serve as during prop governing mode?

A

an oil passage and housing for the beta tube

it also serves as a hydraulic/mechanical minimum pitch stop. the governor cannot decrease blade angle below flight idle

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34
Q

what does the propellor blade angle control do in beta mode?

A

provides for pilot control of the prop blade angle by positioning the beta cam by means of the power lever

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35
Q

how is the desired blade angle set in prop governing mode?

A

metered oil through the beta tube

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36
Q

what does the minimum blade angle follow up do?

A

in the event of NTS failure the low pitch stop is automatically readjusted to a higher blade angle as the power lever is advanced towards max

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37
Q

what is the engine fuel system composed of?

A
  • fuel pump
  • fuel control unit
  • fuel shutoff valve
  • fuel flow divider
  • manifold and nozzle assemblies
  • start/enrich fuel system
  • fuel anti-ice system
  • fuel purge and drain system
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38
Q

what does the engine driven fuel pump assembly consist of?

A

a boost element and a high pressure element with a common drive train

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39
Q

what is the boost element of the engine driven fuel pump?

A

a centrifugal pump which boosts inlet pressure to the high pressure element

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40
Q

what does the high pressure element of the engine driven fuel pump incorporate?

A

an anti-icing valve

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41
Q

what does the engine driven fuel pump do?

A

delivers filtered fuel at the required pressure to the FCU for metering

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42
Q

what does the fuel control assembly consist of?

A

engine driven high pressure fuel pump and the fuel control unit part

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43
Q

what does the fuel control unit do?

A

meters the fuel to the engine combustion chamber

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44
Q

what does the fuel control unit consist of?

A
  • underspeed fuel governor
  • overspeed fuel governor
  • power lever fuel main metering valve
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45
Q

what 2 basic limiting devices establish the fuel flow range in the fuel control unit?

A
  • maximum fuel flow schedule

- minimum fuel flow schedule

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46
Q

how is the maximum fuel flow schedule controlled?

A

functionally controlled by mechanical means and compressor discharge pressure and compensated for compressor inlet pressure and temperature variance

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47
Q

how is the minimum fuel flow schedule controlled?

A

functionally controlled by mechanical means and compressor discharge pressure

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48
Q

what is provided on the FCU to compensate for different fuel types?

A

a manual adjustment externally located on the fuel control unit

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49
Q

when is the underspeed fuel governor functional?

A

at reduced engine speed in beta mode operation

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50
Q

what will the engine speed vary between when the power lever is in FI or below?

A

70 and 97% engine RPM

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51
Q

what will the underspeed fuel governor do if engine speed falls below the selected setting?

A

it will increase the fuel flow to oppose the speed decrease

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52
Q

what is the minimum engine speed setting and what does it provide?

A

70% engine RPM provides a minimum speed during ground operation

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53
Q

what is the maximum engine speed setting and what does it provide?

A

97% engine RPM provides engine speed droop control during reverse thrust operation

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54
Q

what is the overspeed fuel governor used for?

A

it is a safety device to control engine speed in the event of prop governor malfunction

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55
Q

what happens to the overspeed fuel governor in the event of excess engine speed?

A

fuel governor flyweight action reduces the fuel flow to oppose further engine speed increase

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56
Q

what is the overspeed fuel governor set to with the propellor in the start locks?

A

104 +/- 1% engine RPM

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57
Q

what dictates the fuel flow of the main metering valve in flight?

A

the power lever fuel cam position

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58
Q

what dictates the amount of fuel to the engine on the ground?

A

power lever fuel cam position

or

USFG

whichever is higher

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59
Q

what do the P2/P3 sensors do?

A

automatically compensate the fuel flow with varying inlet pressure and temperature (P2T2) and during engine acceleration (P3) to prevent engine surges

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60
Q

where is the main fuel shutoff valve located?

A

downstream of the FCU on the left hand side of the engine forward of the fire wall adapter

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61
Q

what does the fuel shut off valve require to set the valve in the ‘fuel on’ or ‘off’ position?

A

momentary electrical power

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62
Q

what happens to the fuel shutoff valve at approx 10% engine speed during start?

A

the electronic speed sensing switch automatically energises the valve to the fuel on position

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63
Q

how is the fuel shutoff valve electrically energised into the fuel off position?

A

the starter switch is placed in the STOP position to release the mechanical lock and close the valve

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64
Q

how can the fuel shutoff valve be opened during a manual start?

A

MAN IGN switch

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65
Q

how can the fuel shutoff valve be manually closed?

A

positioning the engine speed lever to the shutoff position

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66
Q

what happens when you shut the engine down by means of the engine speed lever?

A

the fuel shutoff valve is manually closed before actuation of the propellor feathering valve

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67
Q

can the fuel shutoff valve be opened electrically when the engine speed lever is in the SHUTOFF position?

A

no, the lever must be returned to the LOW position before the valve can be opened electrically

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68
Q

what does the fuel flow divider do?

A

directs metered fuel into the primary fuel manifold and nozzle assembly during engine start.

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69
Q

when does the fuel flow divider secondary port open and where does it allow metered fuel to flow?

A

it opens as the engine accelerates and the metered fuel pressure increases during start.

it allows metered fuel to flow to the primary and secondary fuel manifold and nozzle assemblies

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70
Q

what are the 2 separate fuel manifold and nozzle assemblies

A

one for primary fuel and one for secondary fuel flow

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71
Q

what does the primary fuel manifold assembly consist of?

A

5 fuel nozzles connected through a manifold to the primary side of the fuel flow divider

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72
Q

what provides fuel atomisation during the initial phases of engine start?

A

the primary nozzles

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73
Q

what provides fuel atomisation for all phases except initial phases of engine start?

A

both the primary and secondary manifolds and nozzles

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74
Q

what does the secondary assembly consist of?

A

10 fuel nozzles connected through a manifold to the secondary side of the fuel flow divider

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75
Q

what does the start/enrich fuel system consist of?

A

an electrical solenoid valve and a pressure regulator

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76
Q

what must be manually activated to add fuel to the starting sequence?

A

ENRICH button

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77
Q

what happens when the enrich button is pressed?

A

pressure regulated fuel bypasses the fuel control unit and is routed through the fuel shutoff valve to the fuel flow divider to aid in the initial engine combustion process

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78
Q

how do we use the start/enrich button to assist smooth engine acceleration?

A

release the button after ITT rise and re engage as necessary to aid smooth starting

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79
Q

what does the activation of the speed switch at 10% RPM achieve?

A
  • it will open the fuel shutoff valve to allow fuel to be introduced into the combustion chamber.
  • it will actuate the ignition system
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80
Q

what does the activation of the speed switch at 55% RPM achieve?

A
  • de energises the starter generator
  • closes the oil vent valve
  • de energises the ignition system and the fuel filter and anti-icing lockout valve
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81
Q

when are the 10% and 55% microswitches disabled?

A

when the start selector switch is in the VENT position

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82
Q

what is the prime function of the oil-fuel heat exchanger?

A

to heat the fuel as required by the fuel anti-ice system

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83
Q

where is the fuel anti-icing valve located?

A

internally in the high pressure pump

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84
Q

how does the fuel filter anti-icing system work?

A

internal porting in the FCU and the high pressure pump assembly directs the heated fuel to a thermostatic valve which is partially open during all fuel flows at which fuel icing can occur and permits mixing of the hot oil fuel heat exchanger discharge fuel with the inlet fuel from the boost pump

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85
Q

in the fuel filter anti-ice system, at what temperature does the thermostatic valve open?

A

starts to open at 10 centigrade and is fully open below 0 centigrade

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86
Q

where does fuel mixing occur in the fuel filter anti ice system?

A

upstream of the fuel filter

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87
Q

when is the anti-icing fuel flow blocked?

A

during engine start by a normally open electrically actuated solenoid valve (solenoid is opened and closed by the engine ignition circuit)

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88
Q

where is the fuel heater located?

A

in the oil tank

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89
Q

what happens to fuel that remains in the fuel flow divider and in the fuel manifold circuit during the shutdown cycle?

A

it is purged into the combustor by an air charge and burned

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90
Q

how is air supplied to the fuel purge system?

A

supplied by an air accumulator which is fully charged at engine RPM above 95% and discharged during the shutdown cycle

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91
Q

how is the purge air discharge regulated?

A

by a normally closed solenoid valve that Is opened by actuation of the starter switch to STOP for at least 5 seconds or until engine speed decreases below 50% RPM

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92
Q

is the fuel purge system self testing?

A

yes- we can tell since burning of the residual manifold fuel causes a momentary increase in engine speed and ITT that can be observed during shutdown

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93
Q

under normal circumstances should there be any residual fuel discharge from the turbine plenum drain valves?

A

no

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94
Q

what do the 2 turbine plenum drain valves allow?

A

allow the turbine plenum to drain automatically during shutdown

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95
Q

what is each turbine plenum drain valve connected to?

A

an airplane overboard drain line

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96
Q

how do the turbine plenum drain valves open and close?

A

they sense a predetermined differential pressure during start which causes them to close during normal engine operation

when shutdown occurs, they re open at the predetermined differential pressure and and remain open during shutdown to drain residual fuel from the turbine plenum

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97
Q

what 2 components make up the negative torques sensing system?

A

the torque sensor and the propellor feathering valve

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98
Q

how is the propellor feathering valve in the NTS controlled?

A

pressure modulated by the torque sensor but also manually actuated by the engine speed lever

99
Q

what is the function of the negative torque sensing system?

A

to limit the torque the engine can extract from the propellor during windmilling and thereby prevent large drag forces

100
Q

what will the NTS do if the engine suddenly loses power in flight?

A

NTS automatically changes the propellor to a high blade angle to minimise drag

101
Q

what does the NTS do during an air start?

A

modulates the propellor blade angle to minimise asymmetric drag

102
Q

what ensures proper propellor response during an RTO and/or high speed landing reverse?

A

a negative torque sensor lockout and propellor governor reset to 105% RPM engine speed

103
Q

what does the NTS do at power lever positions below FI?

A

the NTS lockout dumps NTS supply pressure and at the same time the prop governor resets to 105% RPM engine speed so that maximum pressure is supplied to the prop control

104
Q

how do we check the NTS system?

A

the NTS test button which activates the unfeathering pump to provide operating pressure under static condition

105
Q

what will tell us the NTS system is ready?

A

the light will illuminate when we press the test button

106
Q

what if the light does not illuminate when we test the NTS?

A

the system is in operation if the power lever is in the normal flight range

or indicates a cut out function when the power lever is below FI

107
Q

what is the ITT and torque limiting system factory preset to?

A

923 centigrade

100% torque

this is to limit the engines electro-hydraulically to theses values by bypassing fuel at the FCU

108
Q

how do we test the ITT and torque limiting system?

A

the system will be tested at partial power on the ground by selection of a spring-loaded TEST switch to either ITT or TORQ

109
Q

how can we switch off the ITT and torque limiting system in the event of a malfunction?

A

ENG LIMIT switch,

the torque and ITT indicators will continue to operate normally

110
Q

what is the engine speed lever in the cockpit connected to?

A

the USFG, the propellor governor, high pressure fuel shutoff in the corresponding engine

111
Q

when the engine speed lever is set to high what is:

  1. the underspeed fuel governor in the FCU set to?
  2. the propellor set to?
A
  1. 97% RPM for the beta ground operating mode

2. 100% RPM for propellor governing mode during flight

112
Q

what are the 5 positions/range of the engine speed lever?

A
  • high
  • cruise range
  • low
  • shutoff range
  • feather
113
Q

what is the lowest RPM the prop governor can be set to in cruise range?

A

96%

114
Q

what is the underspeed fuel governor set to in LOW speed lever position?

A

70% RPM

115
Q

what is the prop governor set to when the speed lever is set to LOW?

A

minimum stop at 94% engine speed

116
Q

what happens when the speed lever is in SHUTOFF RANGE?

A

high pressure fuel shutoff valve is closed via a mechanical linkage.

117
Q

how is the speed lever moved from low to shutoff?

A

lever must be lifted and pulled back against increasing spring pressure

118
Q

what does the FEATHER position on the speed lever do?

A

actuates the propellor feather mechanism

119
Q

how do we get the speed lever in and out of FEATHER position?

A

push the lever in to hold it in position and pull it up to release it out of feather.

120
Q

what is the power lever connected to?

A

the beta cam and the power lever fuel cam in the FCU

121
Q

what positions/range does the power lever have?

A
  • max
  • FI (flight idle)
  • START
  • GI (ground idle)
  • REVERSE
122
Q

what does MAX power lever position provide?

A

highest possible fuel flow (torque) for takeoff and inflight.

123
Q

what happens to the blade angle when power lever is set to MAX?

A

minimum propellor blade angle is set to its highest value by the minimum propellor blade angle follow up

124
Q

what does FI (flight idle) power lever setting provide?

A

minimum fuel flow and minimum pitch stop for flight

125
Q

what marks the recommended power lever setting for an air start?

A

blue line

126
Q

what marks the recommended power lever setting for a ground start?

A

green line

127
Q

what does the GI (ground idle) power lever setting provide?

A

minimum fuel flow (beta mode ground operation) and appropriate blade angle

128
Q

what does the REVERSE power lever position do?

A

reverse prop blade angle and USFG reset for engine operation to prevent engine bog down

129
Q

what is the power lever range between FI and MAX used for?

A

to select the desired power for a given flight condition

130
Q

what limits power lever movement to between FI and max?

A

mechanical stops at these 2 positions

131
Q

how do we move the power lever back past FI?

A

power lever must be lifted and pulled back

132
Q

how do we move the power lever back past ground idle?

A

the power lever must be pulled back farther across and intentionally installed hard point to help identify lever position during ground ops

133
Q

what is the power lever range in between FI and REVERSE intended for?

A

ground operation only

134
Q

what happens to NTS in between FI and REVERSE?

A

NTS doesn’t function and the prop governor is set to 105% engine speed

135
Q

what should we inspect for damage after operation on gravel?

A
  • prop blades
  • engine air intake, first compressor stage, oil cooler
  • horizontal stabiliser/elevator
  • nose and main gear including electric-hydraulic brakes
  • fuselage lower belly, main gear and nose gear wells, brakes and hydraulic lines
136
Q

what are the friction locks provided for?

A

to prevent engine speed levers and power levers from creeping

137
Q

what does the engine limit switch control?

A

ITT and torque limiting system

138
Q

what does moving the ITT/torque switch momentarily to the upper position (labeled ITT) do?

A

tests the ITT system

139
Q

what does moving the ITT/torque switch momentarily to the lower position (labeled TORQ) do?

A

position checks the torque limiting system

140
Q

what is the prop unfeathring pump used for?

A

to unfeather the prop during engine out operation or to engage the start locks

141
Q

what does the unfeathering pump do during certain ground operations/airstart?

A

the electric pump uses engine oil to force the prop against spring pressure to decrease blade angle

142
Q

why can we not activate the unfeathering pump with the engine speed lever in the FEATHER position?

A

the engine oil from the tank may be pumped into the oil sump

143
Q

when the power lever is selected to reverse and the UNF pump is set to ON, what happens?

A

oil pressure from the unfeathering pumps delivered to the prop assembly, causing the blades to move to the preselected REVERSE position

144
Q

what powers the unfeathering pump?

A

28v DC

145
Q

what protects the unfeathering pumps?

A

PROP-SYST LH / ESS BUS on the overhead breaker panel

PROP-SYST RH/ESS BUS on the overhead breaker panel

146
Q

what does the propellor synchrophaser system do?

A

automatically adjusts propellor governor speed setting to match the speed of the 2 engines

147
Q

how does the propellor synchorphaser system work?

A

a magnetic pickup mounted on a bracket behind the prop spinner transmits speed signals to the control box. these impulses are compared in the control box which sends corrective signals to the coils in the governor, thus synchronising the engines

both governors act together to form a mutually coordinated, responsive system

148
Q

what powers the prop synchrophaser system?

A

28v DC

149
Q

what protects the prop synchrophaser system?

A

PROP-SYST LH/ESS BUS on the overhead breaker panel

PROP-SYST RH/ESS BUS on the overhead breaker panel

150
Q

what will happen if the prop synchrophaser control is set to ON?

A

if the engines are manually synchronised within 0.5% of eachother the engines will be synchronised to a zero speed difference

151
Q

how much may the synchronised engine rpm differ from the original setting?

A

1%

152
Q

what will turning the prop synchophaser knob to PHASE SELECT do?

A

will place the propellors in the desired phase relation with each other to minimise prop noise

153
Q

when must the prop synchrophasing system be off?

A

takeoff, landing, single engine ops

154
Q

can malfunction of the synchrophaser prevent normal operation of the engines?

A

no

155
Q

what action do we take if the synchrophaser system is unable to match speeds?

A

turn the system off, synchronise manually and then turn the system on

156
Q

what does the torque indicator indicate?

A

torque between engine and propellor in %

157
Q

what range does the torque indicator display?

A

0-120

158
Q

what does the torque indicator receive output signal from?

A

torque pressure tranducer

159
Q

what powers the torque indicator?

A

28v DC

160
Q

what protects the torque indicator?

A
  • TORQ LH/BUS 1 on the overhead circuit breaker panel

- TORQ RH/BUS 2 on the AC/DC breaker panel

161
Q

what will the torque indicator indicate when electrical power is lost?

A

OFF

162
Q

what does the ITT indicator for each engine display?

A

temperature between the first and second stage turbine wheels in degrees C

163
Q

what temperature range does the ITT indicator show?

A

300-1200 C

164
Q

what powers the ITT indicator?

A

28v DC

165
Q

what protects the ITT indicator?

A

ITT LH/BUS 1 on the overhead breaker panel

ITT RH/ESS BUS on the overhead breaker panel

166
Q

what is the RPM indicator?

A

a tachometer which indicates engine speed in revolutions per minute

167
Q

what range of RPM does the RPM indicator show?

A

0-110%

168
Q

what provides signals for operation of the RPM indicator?

A

a tachometer generator at the rear end of the reduction gearing

169
Q

what powers the RPM indicator?

A

28v DC

170
Q

what protects the RPM indicator?

A

RPM LH/BUS 1 on the overhead breaker panel

RPM RH/ESS BUS on the overhead breaker panel

171
Q

what will the RPM indicator show without electrical power?

A

digital indication will be inop

analog part indicates 0

172
Q

what scale of oil pressure does the oil pressure/temperature indicator display?

A

0-150 psi

173
Q

what scale of oil temperature does the oil pressure/temperature indicator display?

A

-70 to +150C

174
Q

what is the oil temperature/pressure indicator powered by?

A

28V DC

175
Q

what protects the oil pressure/temperature indicator?

A

OIL LH/BUS 1 on the overhead breaker panel

OIL RH/BUS 2 on the AC/DC circuit breaker panel

176
Q

what will happen to the oil temperature/pressure indicator when electrical power is lost?

A

both pointers will fall to zero

177
Q

when will the blue beta light illuminate?

A

whenever the corresponding propellor is at the minimum blade angle stop, indicating that the system is in beta mode of operation

178
Q

what does the engine lubrication systems internal pressure pump provide?

A

jet and spray lubrication of engine bearings and gears

179
Q

what 5 components makeup the engine oil system?

A
  • tank
  • pump
  • oil-fuel heat exchanger
  • oil air heat exchanger
  • filter
180
Q

what is the operating pressure range of the engine lubricating system?

A

40-120psi

181
Q

what may happen to engine oil pressure with altitude?

A

decrease

182
Q

at what altitude will the engine oil pressure stabilise below 70psi?

A

23,000ft

183
Q

below what oil pressure should the engine oil not stabilise at?

A

50psi

184
Q

what does the engine lubrication system also supply oil to?

A

propellor control system

it provides oil to actuate the engine torque sensing components

185
Q

what does the oil tank attached to the lower side of the reduction gear case provide?

A

the oil reservoir for lubrication of the engine and prop governing

186
Q

what components does the oil tank assembly include?

A
  • drain plug
  • filler opening with filter
  • air-oil separator
  • overboard vent
  • dipstick
  • connection for supplying oil to the unfeathering pump
187
Q

where is the oil tank vented to?

A

reduction gear case

188
Q

what does the oil pressure pump do?

A

it delivers oil from the oil tank through a pressure regulator and a filter into the reduction gear housing, where the oil is directed to bearings and gears

189
Q

how does lubricating oil get from the pressure pump to the rear bearing?

A

external line carries it to an oil jet

190
Q

what provides pressurised oil to the torque sensing system and propellor governor?

A

oil pressure pump

191
Q

where are the 2 oil scavenge pumps located?

A

one in the gear case and one in the tail cone

192
Q

where is the oil picked up by the scavenge pumps?

A

the sump in the bottom of the reduction gear housing or the tail cone

193
Q

where does oil go from the scavenge pumps?

A

back into the tank via the oil-air heat exchanger and oil-fuel heat exchanger

194
Q

how does the oil-air heat exchanger dissipate heat?

A

temperature controlled bypass valve

195
Q

how does the oil-air heat exchanger maintain the desired temperature?

A

the oil is allowed to bypass the exchanger or flow through it as required

196
Q

what makes up the oil filter?

A

a replaceable paper filter element on the aft face of the reduction gear case

197
Q

what does the oil vent valve do?

A

serves to reduce the load of the oil pumps during the initial engine starting phase to facilitate the cranking of the engine

198
Q

when will the oil vent valve open?

A

it will be opened when switching the starter switch to start and will remain open until approx 55% RPM

199
Q

what does the starting system consist of?

A

mainly the starter generator acting as a starter up to 55% RPM and as a generator once above 55%

200
Q

what is provided to energise the igniter plugs in the ignition system?

A

continuous ignition system

201
Q

what power electrical input does the ignition system require?

A

10-30 volts DC

202
Q

what will operation of the igniter at conditions other than normal starting cause?

A

reduces the igniter plug life

203
Q

what 3 components make up the ignition system?

A
  • an ignition unit
  • 2 igniter plugs
  • a manual ignition switch
204
Q

what does the ignition unit do?

A

energises the igniter plugs to ignite the fuel-air mixture during an engine start

205
Q

what controls the ignition unit?

A

the engine electrical speed sensing switches during an automatic start or manually using the manual ignition switch

206
Q

what powers the ignition system?

A

28V DC

207
Q

what protects the ignition system?

A

IGNITION LH/ESS BUS on the overhead breaker panel

IGNITION RH/ESS BUS on the overhead breaker panel

208
Q

where are the 2 igniter plugs mounted?

A

the outer turbine plenum and extend through the turbine plenum into the internal combustion chamber

209
Q

how can the engine be started in the event of speed switch failure?

A

automatically or manually

210
Q

what RPM does the engine starter generator drive the engine to for a ground start?

A

55 +/-5% RPM

211
Q

what is used instead of the starter motor for an air start?

A

windmilling forces

212
Q

how is the prop moved out of the feather position during start?

A

either aerodynamic forces or manually through operation of the unfeathering pump

213
Q

when is fuel and ignition introduced during start?

A

10% RPM either automatically or manually through the electronic speed switch

214
Q

what can we do to assist a cold start?

A

manually add fuel usage the ENRICH button

215
Q

what happens to the power fed to the ignition and starter once 55 +/- 5% RPM is reached during start?

A

it is cut off

216
Q

when would we use continuous ignition?

A

to prevent engine flameout during heavy precipitation or in icing conditions

217
Q

what is the maximum operating time (continuous or intermittent of the starter system above 10C?)

A

1 hour (followed by 1 hour of non operation)

218
Q

what does the GROUND position of the start selector switch do?

A

start using the starter generator is initiated when the starter switch is actuated

the engine limiting system is disconnected until approx 55% RPM

219
Q

what does the VENT position of the start selector switch do?

A

automatic ignition and fuel circuits are deactivated.

this position is used for engine motoring or manual start. that starter switch has to be held in the start position for operation

220
Q

what does the AIR position of the start selector switch do?

A

in this position the starter motor is inactive, when activating the starter switch the unfeathering pump will be activated- engine RPM is provided by windmilling forces.

221
Q

when will the ignition and fuel cut in when the start selector is in the AIR position?

A

approx 10% RPM

222
Q

what will happen when the starter switch is set to START?

A

power will be applied to the starter motor when the START selector switch is in the position GROUND or VENT

in the AIR position, the unfeathering pump will be activated

223
Q

what will happen when the starter switch is set to STOP?

A

the starter is disengaged, or the unfeathering pump is deactivated

the fuel solenoid valve in the fuel lines closes causing engine shutdown due to fuel starvation and the fuel purge system is activated

224
Q

what is the first indication after pushing the starter switch to START?

A

a rise in RPM

225
Q

how ling met the starter switch be held in the STOP position during a normal engine shutdown?

A

5 seconds minimum or down to approx 50% engine RPM

226
Q

What happens during shutdown when the starter switch is held in the STOP position?

A

the fuel purge system is actuated if engine speed has exceeded 95% before shutdown

227
Q

what may happen if the STOP position on the starter switch is held for less than 5 seconds during shutdown?

A

the purge system may not completely discharge and some fuel may drain through the drain valves

228
Q

where is the manual ignition switch?

A

LH overhead switch panel

229
Q

what are the 3 positions of the manual initial switch?

A
  • CONT
  • OFF
  • START (must be held in this position to manual start)
230
Q

when will the ignition lights illuminate?

A

whenever ignition is applied

231
Q

what are the 5 engine accessories?

A
  • 2 oil pump assemblies
  • fuel control and pump assembly
  • starter generator
  • tacho-generator
  • prop governor
232
Q

where are the engine accessories located?

A

accessory gearbox or in the mounting pads on the aft side of the engine reduction gear case

233
Q

what does the engine fire detection system comprise?

A

2 temp sensors

a control unit

2 warning light test circuits

234
Q

what powers the engine fire detection system?

A

28V DC

235
Q

what protects the engines fire detection system?

A

FIRE-WARN LH/ ESS BUS on the overhead breaker panel

FIRE WARN RH/ESS BUS ON OVERHEAD BREAKER PANEL

236
Q

what happens if the fire detection system senses excessive heat in an engine nacelle?

A

temperature sensors energise a relay, causing the appropriate red FIRE warning to illuminate and triggering a master warning

237
Q

what will happen if the temperature decreases in the nacelle after the fire detection system is triggered?

A

the fire warning light will extinguish and the system is rearmed automatically

238
Q

what does the fire extinguishing system consist of?

A

2 independent bottles, a squib assembly, discharge pipes and operating handles

239
Q

what are the fire extinguisher bottles charged with?

A

HALON 1301

240
Q

how is the fire extinguishing bottle discharged?

A

discharged via nozzles into the associate nacelle

241
Q

what will tell us an extinguisher bottle is no longer serviceable?

A

green disk seal is not visible upon inspection

242
Q

what powers the engine fire extinguishing system?

A

24/28V DC

243
Q

what protects the engine fire extinguishing system?

A

FIRE LH/HOT BUS 1 in the battery compartment

FIRE RH/HOT BUS 1 in the battery compartment

DO228 type rating (22 decks)

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