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
2
Q
what kind of engine is the TPE 331-5(B)-252D?
A
lightweight single shaft turboprop engine
3
Q
what further pressurises fuel supplied to the engine from the fuel system?
A
engine driven fuel pumps
4
Q
what controls fuel flow to the engine fuel manifolds?
A
fuel control unit (FCU)
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
6
Q
how is the engine started on the ground?
A
an electrical starter-generator which turns the rotating group through a gear train
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
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
9
Q
what kind of propellor does the DO228 have?
A
Hartzell HC-B4TN- 5ML/LT 10574 propellor
10
Q
what does the type of prop blade installed depend on?
A
the ice protection installed
11
Q
what is propellor blade angle controlled by?
A
a governor installed on the engine supplying engine oil through the propellor shaft
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
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
14
Q
how is unfeathring accomplished?
A
unfeathering pump
15
Q
what holds the props in a fine pitch during ground starting?
A
spring actuated start locks
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
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
18
Q
below what RPM will the start locks engage?
A
approx 10%
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
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
21
Q
what 2 basic modes does the power management system provide?
A
beta mode and prop governing mode
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.
23
Q
when is beta mode utilised?
A
all ground operation
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.
25
when is prop governing mode used?
all flight operations
26
what constant engine speed dos the governor provide?
96-100% RPM
27
how is engine oil pressure boosted and controlled into the propellor hub?
by the governor via the beta tube to balance the feathering forces of the prop
28
where is the beta pressure switch installed?
in the propellor oil control system.
29
what does the beta pressure switch do?
powers a blue beta light, located on the cockpit instrument panel
30
what does the blue beta light indicate?
indicates the propellor is operating in beta mode and extinguishes when in prop governing mode
31
is there a requirement for the beta light to be on below a high RPM setting?
no
32
how does the prop blade angle control/beta servo position the blade angle?
it holds the beta cam which provides metered oil through the beta tube
33
what does the propellor blade angle control serve as during prop governing mode?
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
34
what does the propellor blade angle control do in beta mode?
provides for pilot control of the prop blade angle by positioning the beta cam by means of the power lever
35
how is the desired blade angle set in prop governing mode?
metered oil through the beta tube
36
what does the minimum blade angle follow up do?
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
37
what is the engine fuel system composed of?
- 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
38
what does the engine driven fuel pump assembly consist of?
a boost element and a high pressure element with a common drive train
39
what is the boost element of the engine driven fuel pump?
a centrifugal pump which boosts inlet pressure to the high pressure element
40
what does the high pressure element of the engine driven fuel pump incorporate?
an anti-icing valve
41
what does the engine driven fuel pump do?
delivers filtered fuel at the required pressure to the FCU for metering
42
what does the fuel control assembly consist of?
engine driven high pressure fuel pump and the fuel control unit part
43
what does the fuel control unit do?
meters the fuel to the engine combustion chamber
44
what does the fuel control unit consist of?
- underspeed fuel governor
- overspeed fuel governor
- power lever fuel main metering valve
45
what 2 basic limiting devices establish the fuel flow range in the fuel control unit?
- maximum fuel flow schedule
| - minimum fuel flow schedule
46
how is the maximum fuel flow schedule controlled?
functionally controlled by mechanical means and compressor discharge pressure and compensated for compressor inlet pressure and temperature variance
47
how is the minimum fuel flow schedule controlled?
functionally controlled by mechanical means and compressor discharge pressure
48
what is provided on the FCU to compensate for different fuel types?
a manual adjustment externally located on the fuel control unit
49
when is the underspeed fuel governor functional?
at reduced engine speed in beta mode operation
50
what will the engine speed vary between when the power lever is in FI or below?
70 and 97% engine RPM
51
what will the underspeed fuel governor do if engine speed falls below the selected setting?
it will increase the fuel flow to oppose the speed decrease
52
what is the minimum engine speed setting and what does it provide?
70% engine RPM provides a minimum speed during ground operation
53
what is the maximum engine speed setting and what does it provide?
97% engine RPM provides engine speed droop control during reverse thrust operation
54
what is the overspeed fuel governor used for?
it is a safety device to control engine speed in the event of prop governor malfunction
55
what happens to the overspeed fuel governor in the event of excess engine speed?
fuel governor flyweight action reduces the fuel flow to oppose further engine speed increase
56
what is the overspeed fuel governor set to with the propellor in the start locks?
104 +/- 1% engine RPM
57
what dictates the fuel flow of the main metering valve in flight?
the power lever fuel cam position
58
what dictates the amount of fuel to the engine on the ground?
power lever fuel cam position
or
USFG
whichever is higher
59
what do the P2/P3 sensors do?
automatically compensate the fuel flow with varying inlet pressure and temperature (P2T2) and during engine acceleration (P3) to prevent engine surges
60
where is the main fuel shutoff valve located?
downstream of the FCU on the left hand side of the engine forward of the fire wall adapter
61
what does the fuel shut off valve require to set the valve in the 'fuel on' or 'off' position?
momentary electrical power
62
what happens to the fuel shutoff valve at approx 10% engine speed during start?
the electronic speed sensing switch automatically energises the valve to the fuel on position
63
how is the fuel shutoff valve electrically energised into the fuel off position?
the starter switch is placed in the STOP position to release the mechanical lock and close the valve
64
how can the fuel shutoff valve be opened during a manual start?
MAN IGN switch
65
how can the fuel shutoff valve be manually closed?
positioning the engine speed lever to the shutoff position
66
what happens when you shut the engine down by means of the engine speed lever?
the fuel shutoff valve is manually closed before actuation of the propellor feathering valve
67
can the fuel shutoff valve be opened electrically when the engine speed lever is in the SHUTOFF position?
no, the lever must be returned to the LOW position before the valve can be opened electrically
68
what does the fuel flow divider do?
directs metered fuel into the primary fuel manifold and nozzle assembly during engine start.
69
when does the fuel flow divider secondary port open and where does it allow metered fuel to flow?
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
70
what are the 2 separate fuel manifold and nozzle assemblies
one for primary fuel and one for secondary fuel flow
71
what does the primary fuel manifold assembly consist of?
5 fuel nozzles connected through a manifold to the primary side of the fuel flow divider
72
what provides fuel atomisation during the initial phases of engine start?
the primary nozzles
73
what provides fuel atomisation for all phases except initial phases of engine start?
both the primary and secondary manifolds and nozzles
74
what does the secondary assembly consist of?
10 fuel nozzles connected through a manifold to the secondary side of the fuel flow divider
75
what does the start/enrich fuel system consist of?
an electrical solenoid valve and a pressure regulator
76
what must be manually activated to add fuel to the starting sequence?
ENRICH button
77
what happens when the enrich button is pressed?
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
78
how do we use the start/enrich button to assist smooth engine acceleration?
release the button after ITT rise and re engage as necessary to aid smooth starting
79
what does the activation of the speed switch at 10% RPM achieve?
- it will open the fuel shutoff valve to allow fuel to be introduced into the combustion chamber.
- it will actuate the ignition system
80
what does the activation of the speed switch at 55% RPM achieve?
- de energises the starter generator
- closes the oil vent valve
- de energises the ignition system and the fuel filter and anti-icing lockout valve
81
when are the 10% and 55% microswitches disabled?
when the start selector switch is in the VENT position
82
what is the prime function of the oil-fuel heat exchanger?
to heat the fuel as required by the fuel anti-ice system
83
where is the fuel anti-icing valve located?
internally in the high pressure pump
84
how does the fuel filter anti-icing system work?
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
85
in the fuel filter anti-ice system, at what temperature does the thermostatic valve open?
starts to open at 10 centigrade and is fully open below 0 centigrade
86
where does fuel mixing occur in the fuel filter anti ice system?
upstream of the fuel filter
87
when is the anti-icing fuel flow blocked?
during engine start by a normally open electrically actuated solenoid valve (solenoid is opened and closed by the engine ignition circuit)
88
where is the fuel heater located?
in the oil tank
89
what happens to fuel that remains in the fuel flow divider and in the fuel manifold circuit during the shutdown cycle?
it is purged into the combustor by an air charge and burned
90
how is air supplied to the fuel purge system?
supplied by an air accumulator which is fully charged at engine RPM above 95% and discharged during the shutdown cycle
91
how is the purge air discharge regulated?
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
92
is the fuel purge system self testing?
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
93
under normal circumstances should there be any residual fuel discharge from the turbine plenum drain valves?
no
94
what do the 2 turbine plenum drain valves allow?
allow the turbine plenum to drain automatically during shutdown
95
what is each turbine plenum drain valve connected to?
an airplane overboard drain line
96
how do the turbine plenum drain valves open and close?
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
97
what 2 components make up the negative torques sensing system?
the torque sensor and the propellor feathering valve
98
how is the propellor feathering valve in the NTS controlled?
pressure modulated by the torque sensor but also manually actuated by the engine speed lever
99
what is the function of the negative torque sensing system?
to limit the torque the engine can extract from the propellor during windmilling and thereby prevent large drag forces
100
what will the NTS do if the engine suddenly loses power in flight?
NTS automatically changes the propellor to a high blade angle to minimise drag
101
what does the NTS do during an air start?
modulates the propellor blade angle to minimise asymmetric drag
102
what ensures proper propellor response during an RTO and/or high speed landing reverse?
a negative torque sensor lockout and propellor governor reset to 105% RPM engine speed
103
what does the NTS do at power lever positions below FI?
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
how do we check the NTS system?
the NTS test button which activates the unfeathering pump to provide operating pressure under static condition
105
what will tell us the NTS system is ready?
the light will illuminate when we press the test button
106
what if the light does not illuminate when we test the NTS?
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
what is the ITT and torque limiting system factory preset to?
923 centigrade
100% torque
this is to limit the engines electro-hydraulically to theses values by bypassing fuel at the FCU
108
how do we test the ITT and torque limiting system?
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
how can we switch off the ITT and torque limiting system in the event of a malfunction?
ENG LIMIT switch,
the torque and ITT indicators will continue to operate normally
110
what is the engine speed lever in the cockpit connected to?
the USFG, the propellor governor, high pressure fuel shutoff in the corresponding engine
111
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?
1. 97% RPM for the beta ground operating mode
| 2. 100% RPM for propellor governing mode during flight
112
what are the 5 positions/range of the engine speed lever?
- high
- cruise range
- low
- shutoff range
- feather
113
what is the lowest RPM the prop governor can be set to in cruise range?
96%
114
what is the underspeed fuel governor set to in LOW speed lever position?
70% RPM
115
what is the prop governor set to when the speed lever is set to LOW?
minimum stop at 94% engine speed
116
what happens when the speed lever is in SHUTOFF RANGE?
high pressure fuel shutoff valve is closed via a mechanical linkage.
117
how is the speed lever moved from low to shutoff?
lever must be lifted and pulled back against increasing spring pressure
118
what does the FEATHER position on the speed lever do?
actuates the propellor feather mechanism
119
how do we get the speed lever in and out of FEATHER position?
push the lever in to hold it in position and pull it up to release it out of feather.
120
what is the power lever connected to?
the beta cam and the power lever fuel cam in the FCU
121
what positions/range does the power lever have?
- max
- FI (flight idle)
- START
- GI (ground idle)
- REVERSE
122
what does MAX power lever position provide?
highest possible fuel flow (torque) for takeoff and inflight.
123
what happens to the blade angle when power lever is set to MAX?
minimum propellor blade angle is set to its highest value by the minimum propellor blade angle follow up
124
what does FI (flight idle) power lever setting provide?
minimum fuel flow and minimum pitch stop for flight
125
what marks the recommended power lever setting for an air start?
blue line
126
what marks the recommended power lever setting for a ground start?
green line
127
what does the GI (ground idle) power lever setting provide?
minimum fuel flow (beta mode ground operation) and appropriate blade angle
128
what does the REVERSE power lever position do?
reverse prop blade angle and USFG reset for engine operation to prevent engine bog down
129
what is the power lever range between FI and MAX used for?
to select the desired power for a given flight condition
130
what limits power lever movement to between FI and max?
mechanical stops at these 2 positions
131
how do we move the power lever back past FI?
power lever must be lifted and pulled back
132
how do we move the power lever back past ground idle?
the power lever must be pulled back farther across and intentionally installed hard point to help identify lever position during ground ops
133
what is the power lever range in between FI and REVERSE intended for?
ground operation only
134
what happens to NTS in between FI and REVERSE?
NTS doesn't function and the prop governor is set to 105% engine speed
135
what should we inspect for damage after operation on gravel?
- 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
what are the friction locks provided for?
to prevent engine speed levers and power levers from creeping
137
what does the engine limit switch control?
ITT and torque limiting system
138
what does moving the ITT/torque switch momentarily to the upper position (labeled ITT) do?
tests the ITT system
139
what does moving the ITT/torque switch momentarily to the lower position (labeled TORQ) do?
position checks the torque limiting system
140
what is the prop unfeathring pump used for?
to unfeather the prop during engine out operation or to engage the start locks
141
what does the unfeathering pump do during certain ground operations/airstart?
the electric pump uses engine oil to force the prop against spring pressure to decrease blade angle
142
why can we not activate the unfeathering pump with the engine speed lever in the FEATHER position?
the engine oil from the tank may be pumped into the oil sump
143
when the power lever is selected to reverse and the UNF pump is set to ON, what happens?
oil pressure from the unfeathering pumps delivered to the prop assembly, causing the blades to move to the preselected REVERSE position
144
what powers the unfeathering pump?
28v DC
145
what protects the unfeathering pumps?
PROP-SYST LH / ESS BUS on the overhead breaker panel
PROP-SYST RH/ESS BUS on the overhead breaker panel
146
what does the propellor synchrophaser system do?
automatically adjusts propellor governor speed setting to match the speed of the 2 engines
147
how does the propellor synchorphaser system work?
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
what powers the prop synchrophaser system?
28v DC
149
what protects the prop synchrophaser system?
PROP-SYST LH/ESS BUS on the overhead breaker panel
PROP-SYST RH/ESS BUS on the overhead breaker panel
150
what will happen if the prop synchrophaser control is set to ON?
if the engines are manually synchronised within 0.5% of eachother the engines will be synchronised to a zero speed difference
151
how much may the synchronised engine rpm differ from the original setting?
1%
152
what will turning the prop synchophaser knob to PHASE SELECT do?
will place the propellors in the desired phase relation with each other to minimise prop noise
153
when must the prop synchrophasing system be off?
takeoff, landing, single engine ops
154
can malfunction of the synchrophaser prevent normal operation of the engines?
no
155
what action do we take if the synchrophaser system is unable to match speeds?
turn the system off, synchronise manually and then turn the system on
156
what does the torque indicator indicate?
torque between engine and propellor in %
157
what range does the torque indicator display?
0-120
158
what does the torque indicator receive output signal from?
torque pressure tranducer
159
what powers the torque indicator?
28v DC
160
what protects the torque indicator?
- TORQ LH/BUS 1 on the overhead circuit breaker panel
| - TORQ RH/BUS 2 on the AC/DC breaker panel
161
what will the torque indicator indicate when electrical power is lost?
OFF
162
what does the ITT indicator for each engine display?
temperature between the first and second stage turbine wheels in degrees C
163
what temperature range does the ITT indicator show?
300-1200 C
164
what powers the ITT indicator?
28v DC
165
what protects the ITT indicator?
ITT LH/BUS 1 on the overhead breaker panel
ITT RH/ESS BUS on the overhead breaker panel
166
what is the RPM indicator?
a tachometer which indicates engine speed in revolutions per minute
167
what range of RPM does the RPM indicator show?
0-110%
168
what provides signals for operation of the RPM indicator?
a tachometer generator at the rear end of the reduction gearing
169
what powers the RPM indicator?
28v DC
170
what protects the RPM indicator?
RPM LH/BUS 1 on the overhead breaker panel
RPM RH/ESS BUS on the overhead breaker panel
171
what will the RPM indicator show without electrical power?
digital indication will be inop
analog part indicates 0
172
what scale of oil pressure does the oil pressure/temperature indicator display?
0-150 psi
173
what scale of oil temperature does the oil pressure/temperature indicator display?
-70 to +150C
174
what is the oil temperature/pressure indicator powered by?
28V DC
175
what protects the oil pressure/temperature indicator?
OIL LH/BUS 1 on the overhead breaker panel
OIL RH/BUS 2 on the AC/DC circuit breaker panel
176
what will happen to the oil temperature/pressure indicator when electrical power is lost?
both pointers will fall to zero
177
when will the blue beta light illuminate?
whenever the corresponding propellor is at the minimum blade angle stop, indicating that the system is in beta mode of operation
178
what does the engine lubrication systems internal pressure pump provide?
jet and spray lubrication of engine bearings and gears
179
what 5 components makeup the engine oil system?
- tank
- pump
- oil-fuel heat exchanger
- oil air heat exchanger
- filter
180
what is the operating pressure range of the engine lubricating system?
40-120psi
181
what may happen to engine oil pressure with altitude?
decrease
182
at what altitude will the engine oil pressure stabilise below 70psi?
23,000ft
183
below what oil pressure should the engine oil not stabilise at?
50psi
184
what does the engine lubrication system also supply oil to?
propellor control system
it provides oil to actuate the engine torque sensing components
185
what does the oil tank attached to the lower side of the reduction gear case provide?
the oil reservoir for lubrication of the engine and prop governing
186
what components does the oil tank assembly include?
- drain plug
- filler opening with filter
- air-oil separator
- overboard vent
- dipstick
- connection for supplying oil to the unfeathering pump
187
where is the oil tank vented to?
reduction gear case
188
what does the oil pressure pump do?
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
how does lubricating oil get from the pressure pump to the rear bearing?
external line carries it to an oil jet
190
what provides pressurised oil to the torque sensing system and propellor governor?
oil pressure pump
191
where are the 2 oil scavenge pumps located?
one in the gear case and one in the tail cone
192
where is the oil picked up by the scavenge pumps?
the sump in the bottom of the reduction gear housing or the tail cone
193
where does oil go from the scavenge pumps?
back into the tank via the oil-air heat exchanger and oil-fuel heat exchanger
194
how does the oil-air heat exchanger dissipate heat?
temperature controlled bypass valve
195
how does the oil-air heat exchanger maintain the desired temperature?
the oil is allowed to bypass the exchanger or flow through it as required
196
what makes up the oil filter?
a replaceable paper filter element on the aft face of the reduction gear case
197
what does the oil vent valve do?
serves to reduce the load of the oil pumps during the initial engine starting phase to facilitate the cranking of the engine
198
when will the oil vent valve open?
it will be opened when switching the starter switch to start and will remain open until approx 55% RPM
199
what does the starting system consist of?
mainly the starter generator acting as a starter up to 55% RPM and as a generator once above 55%
200
what is provided to energise the igniter plugs in the ignition system?
continuous ignition system
201
what power electrical input does the ignition system require?
10-30 volts DC
202
what will operation of the igniter at conditions other than normal starting cause?
reduces the igniter plug life
203
what 3 components make up the ignition system?
- an ignition unit
- 2 igniter plugs
- a manual ignition switch
204
what does the ignition unit do?
energises the igniter plugs to ignite the fuel-air mixture during an engine start
205
what controls the ignition unit?
the engine electrical speed sensing switches during an automatic start or manually using the manual ignition switch
206
what powers the ignition system?
28V DC
207
what protects the ignition system?
IGNITION LH/ESS BUS on the overhead breaker panel
IGNITION RH/ESS BUS on the overhead breaker panel
208
where are the 2 igniter plugs mounted?
the outer turbine plenum and extend through the turbine plenum into the internal combustion chamber
209
how can the engine be started in the event of speed switch failure?
automatically or manually
210
what RPM does the engine starter generator drive the engine to for a ground start?
55 +/-5% RPM
211
what is used instead of the starter motor for an air start?
windmilling forces
212
how is the prop moved out of the feather position during start?
either aerodynamic forces or manually through operation of the unfeathering pump
213
when is fuel and ignition introduced during start?
10% RPM either automatically or manually through the electronic speed switch
214
what can we do to assist a cold start?
manually add fuel usage the ENRICH button
215
what happens to the power fed to the ignition and starter once 55 +/- 5% RPM is reached during start?
it is cut off
216
when would we use continuous ignition?
to prevent engine flameout during heavy precipitation or in icing conditions
217
what is the maximum operating time (continuous or intermittent of the starter system above 10C?)
1 hour (followed by 1 hour of non operation)
218
what does the GROUND position of the start selector switch do?
start using the starter generator is initiated when the starter switch is actuated
the engine limiting system is disconnected until approx 55% RPM
219
what does the VENT position of the start selector switch do?
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
what does the AIR position of the start selector switch do?
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
when will the ignition and fuel cut in when the start selector is in the AIR position?
approx 10% RPM
222
what will happen when the starter switch is set to START?
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
what will happen when the starter switch is set to STOP?
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
what is the first indication after pushing the starter switch to START?
a rise in RPM
225
how ling met the starter switch be held in the STOP position during a normal engine shutdown?
5 seconds minimum or down to approx 50% engine RPM
226
What happens during shutdown when the starter switch is held in the STOP position?
the fuel purge system is actuated if engine speed has exceeded 95% before shutdown
227
what may happen if the STOP position on the starter switch is held for less than 5 seconds during shutdown?
the purge system may not completely discharge and some fuel may drain through the drain valves
228
where is the manual ignition switch?
LH overhead switch panel
229
what are the 3 positions of the manual initial switch?
- CONT
- OFF
- START (must be held in this position to manual start)
230
when will the ignition lights illuminate?
whenever ignition is applied
231
what are the 5 engine accessories?
- 2 oil pump assemblies
- fuel control and pump assembly
- starter generator
- tacho-generator
- prop governor
232
where are the engine accessories located?
accessory gearbox or in the mounting pads on the aft side of the engine reduction gear case
233
what does the engine fire detection system comprise?
2 temp sensors
a control unit
2 warning light test circuits
234
what powers the engine fire detection system?
28V DC
235
what protects the engines fire detection system?
FIRE-WARN LH/ ESS BUS on the overhead breaker panel
FIRE WARN RH/ESS BUS ON OVERHEAD BREAKER PANEL
236
what happens if the fire detection system senses excessive heat in an engine nacelle?
temperature sensors energise a relay, causing the appropriate red FIRE warning to illuminate and triggering a master warning
237
what will happen if the temperature decreases in the nacelle after the fire detection system is triggered?
the fire warning light will extinguish and the system is rearmed automatically
238
what does the fire extinguishing system consist of?
2 independent bottles, a squib assembly, discharge pipes and operating handles
239
what are the fire extinguisher bottles charged with?
HALON 1301
240
how is the fire extinguishing bottle discharged?
discharged via nozzles into the associate nacelle
241
what will tell us an extinguisher bottle is no longer serviceable?
green disk seal is not visible upon inspection
242
what powers the engine fire extinguishing system?
24/28V DC
243
what protects the engine fire extinguishing system?
FIRE LH/HOT BUS 1 in the battery compartment
FIRE RH/HOT BUS 1 in the battery compartment
