PTM Ch. 7 Powerplant Flashcards
1
Q
What kind of engine do we have?
A
Garrett TPE331-11U-612G
Two stage centrifugal compressor and a three-stage, axial-flow turbine on a single shaft. An annular, reverse flow combustor surrounds the turbine.
2
Q
What reduces the engine RPM from 41,730 to 1591?
A
Planetary gear box
3
Q
What does stage 1 in the engine represent?
A
Ambient conditions outside the engine.
4
Q
What does stage 2 represent?
A
Compressor inlet
5
Q
What does stage 3 represent?
A
Compressor discharge
6
Q
What does station 4 represent?
A
Turbine inlet
7
Q
What does station 5 represent?
A
Turbine discharge or exhaust
8
Q
What are the six accessories driven by the reduction gear?
A
- Fuel control and engine driven fuel pumps
- Hydraulic pump
- Starter-generator
- Tach generator
- Propeller governor
- Oil pump
9
Q
What is the compression ratio?
A
10:1
10
Q
What portion of the compressor discharge air is used to support actual fuel combustion?
A
1/3
11
Q
What portion of the compressor is used to center the flame within the combustion chamber and to reduce the temperature of the air entering the turbine?
A
2/3
12
Q
The combustor is an annular, reverse flow type with how many duplex nozzles and how many igniter plugs?
A
10 duplex nozzles
2 igniter plugs
13
Q
What portion of turbine power is applied to the propeller shaft through the reduction gear?
A
1/3
14
Q
What portion of the power generated by the turbine is used to drive compressor?
A
2/3
15
Q
Below what percentage is EGT compensated?
A
80%
16
Q
Above what percentage is EGT computed?
A
80%
17
Q
What will happen to engine instruments if their respective essential bus fails?
A
Auto transfer to opposite essential bus.
18
Q
What are the three functions of the SRL?
A
- Engine speed switching functions
- Automatic start fuel enrichment
- Single red line EGT computation
19
Q
The SRL has automatic control of the start sequence from what percentages?
A
10-60%
20
Q
SRL does EGT COMPUTATION above what percentage?
A
80%
21
Q
When does CAWI operation and EGT temperature limiting happen from the SRL?
A
Above 90%
22
Q
What are the five inputs to the SRL computer?
A
- Compensated EGT (T5)
- Engine RPM
- Compressor inlet temperature (T2)
- Airspeed and altitude from the delta_P/P (P2/P5)
- Whether or not CAWI is being used
23
Q
If you lose your SRL where do you find the numbers to fly off of?
A
Look at the numbers on the cabin ceiling
24
Q
What are the 5 signs your SRL is malfunctioning?
A
- SRL OFF annunciator ON with RPM above 80%
- SRL OFF annunciator OFF with RPM below 80%
- 20 degrees or more jumps in EGT indication
- Erratic EGT
- Delta_P/P switch OFF
25
If the SRL needs to be deferred, review the following 3 documents:
1. MEL
2. AFM Chapter 3A
3. AFM Supplement 1A
26
If the SRL is inop what will be different about the engine start?
It’ll be a manual start
27
Will temperature limiting be available without an SRL?
No
28
Will CAWI be available without an SRL?
No
29
What RPM is needed for the temperature limiter?
Above 90%
30
Why would the “bypass open” annunciator come on for?
Fuel bypass valve opens to circumvent fuel and keep EGT below 650 dC.
31
What do you do on the takeoff roll if the “bypass open” comes on?
Reduce the power levers until the the annunciator turns off.
32
Should you test the Temp Limiter in flight?
Negative. Engine flameout may result.
33
What is the maximum altitude for prolonged operation with the bypass valve failed open?
15000’
34
RPM must be maintained where with Bypass Valve Failed Open?
99-101 or 96-98%
Just keep it at 100% for T/O and Lnd
Or 97% in cruise
35
Can we takeoff with the Bypass Valve failed open position?
No
36
What 4 things does engine oil do?
1. Cooling and lubricating of main engine bearing and reduction
2. Oil for propeller control
3. NTS - negative torque sensing
4. Unfeathering pump
37
What’s the approved oil?
BP2380
38
When is the best time to check the oil quantity?
Within 10 minutes of shutdown
39
If you can’t check the oil within 10 minutes of shutdown what can you do to check the oil?
Motor the engine to approximately 15%.
40
Where does the engine driven pressure pump draw oil from? What does it supply it to?
Draws from tank and supplies it under pressure to the oil filter.
41
How many scavenge pumps do we have for oil?
3
42
Where are the scavenge pumps located?
2 in gear case and returns oil to tank
1 is located in rear turbine bearing and returns to gear case
43
The gear case scavenge pump oil passes through what on the way back to the tank?
A fuel heater and oil cooler
44
Minimum oil pressure?
40 psi
>23000’ = 50 psi
45
Oil pressure annunciator will illuminate when?
If oil pressure drops below 40 psi or 50 psi above 23000’.
46
When you lower your speed levers from 100 to 97% how much will your EGT rise typically?
A noticeable amount. So reduce power first, let the EGT drop, then reduce speed levers.
47
What does the CHIP DET annunciator mean?
Indicates metal particles in the oil
48
Ignition consists of what?
Engine mounted exciter and 2 igniter plugs located in combustion chamber
49
Ignition is powered by what?
Respective essential bus AUTOMATICALLY transferable to the opposite side.
50
What does the AUTO on the ignition switch do?
Allows the SRL to control during start (10-60%), ignition if NTS is activated
51
What does the CONT on ignition switch do?
Continuous ignition
52
When should you use continuous ignition?
1. <5dC with visible moisture
2. Contaminated runway
3. Turbulence
4. Precipitation
53
What is the OFF on the ignition switch for?
Off but will permit a normal start (not normally used)
54
How many oil pumps in total do we have?
4 total
3 scavenge pumps
1 oil pump
* there is a unfeathering pump however. So maybe 5 total.
55
The vent valve in the oil system opens when?
When you press the start button
56
Why do we need a vent valve in the oil system?
To reduce resistance on oil flowing through the system on startup.
57
What can the unfeathering pump be used for?
1. Put props on start locks if the props were feathered on the ground
2. Used for unfeathering during air start.
58
Engine fuel system includes what seven items?
1. Engine driven high pressure pump
2. Engine driven low pressure pump
3. Fuel control unit (FCU)
4. Fuel solenoid valve
5. Flow divider
6. Fuel manifolds
7. Primary and secondary fuel nozzles
59
What does the fuel control unit do?
Meters the correct amount of fuel to the nozzles
60
What are the inputs to the FCU?
1. Power and speed lever positions
2. Altitude and temperature via P2T2 probe (compressor inlet)
3. Engine RPM
4. Compressor discharge pressure P3
61
What does the FCU contain?
1. Underspeed governor
2. Overspeed governor
3. Manual fuel valve
62
What does the underspeed governor do?
Prevents rpm from going below a value set by the speed lever
63
If the RPM decreases what will the underspeed governor do?
Increase fuel to raise RPM
64
What mode is used during ground operations with the underspeed governor?
Beta mode
65
Underspeed governor is set between what RPM percentages?
71-97% by speed levers
66
What is the overspeed governor for?
Safety device to prevent excessive engine overspeed in the event of propeller malfunction.
67
How does the overspeed governor reduce RPM?
Reduce fuel flow
68
What RPM percentages are the overspeed governor set between?
103-105%
69
What is the Manual Fuel Valve used for?
Direct control of fuel valve with power levers when forward of flight idle
70
If more power is requested with Manual Fuel Valve what does this do?
More fuel metered to engine
71
When does the fuel solenoid valve open?
During start at 10%
72
When does the fuel solenoid close?
Electrically by STOP button
Mechanically with ENGINE STOP AND FEATHER knob.
73
What does the Flow Divider and Primaries-only Solenoid Valve do?
Improves fuel spray pattern during start
74
When does the Flow Divider and Primaries-only Solenoid Valve open and close?
Open at 10%
| Closes at 60%
75
What is the Start Fuel Enrichment Valve for?
Automatic fuel enrichment to assist with engine acceleration
76
What EGT does the Start Fuel Enrichment Valve maintain during start?
690dC
77
What does the Fuel Anti-icing Valve
Allows some engine driven high pressure fuel to be routed through the fuel heater preventing the formation of ice crystals
78
What is the Anti-icing Lockout Valve for?
Closes at activation of START button to prevent fuel from bypassing through to fuel heater for assistance for start.
79
When does the Anti-icing lockout valve open?
At 60%
80
When is the Fuel Bypass Valve active?
Above 90%
81
When would the fuel bypass valve open?
RPM above 90% and EGT exceeds 650 dC
82
What happens when you press the START button?
- anti icing lockout valve closes
- oil vent valve opens
- propeller rotation
83
What happens at 10% RPM?
- Fuel solenoid valve opens
- ignition
- Primary only valve opens
- fuel enrichment valve opens
84
What happens at 60% RPM?
- Anti-lockout lockout valve opens
- Ignition off
- secondary valve opens
- fuel enrichment valve closes
85
What happens at 80%?
- Speeds high, SRL on
| - Computed EGT
86
What happens at 90%?
- Temp limiter armed
| - CAWI available
87
What happens at 96%?
Air accumulator (EPA kit) is armed
88
What should you do during a residual heat start with EGT’s >200dC?
Hold the START TEST switch to the desired L or R position up to 15% RPM
then, momentarily press the START button.
89
How do perform an aborted start?
1. Push STOP button
2. Pull ENGINE STOP AND FEATHER
3. Allow engine to windmill to 0%
4. Clear engine by holding START TEST for 10 s or 15%, whichever occurs first
*DON’T operate in 18-28% RPM range during engine clearing
90
What is a hot start?
RPM stops increasing and/or EGT is above 700dC and rising rapidly, immediately abort the start.
91
What is a hung start?
If EGT rise is not obtained within 10 s after reaching 10% RPM or prior to reaching 20% RPM, abort the start.
92
What can you do if acceleration is sluggish between 10-60% RPM?
Press the START button briefly provides manual fuel enrichment. Monitor EGT carefully and release the START button if EGT reaches 650dC
93
Where do the power levers go for an air start?
1/4 inch forward of FLT IDLE
94
Where do you put the speed levers for an air start?
Around a position where 97% should be.
95
During an air start what happens if the EGT does not rise by 25% RPM?
Abort the start by pulling the ENGINE STOP AND FEATHER
96
Max pressure altitude with boost pumps for an air start?
20,000 ft
97
Max pressure altitude for air start without boost pumps?
12,000 ft
98
Airspeed limits for air start
100-180 KIAS
99
Why do you hold the stop button for a minimum of 5 seconds?
To ensure complete fuel purging
100
How much will the RPM increase on shutdown?
5%
101
Hold the power levers in reverse from what percent range to place the propeller on start locks?
50 down to 10%
102
What’s the cooldown period before stopping engines?
3 minutes
103
What percent must the engine be at for the EPA kit (air accumulator) to charge?
96%
104
Should you ever turn the props in reverse?
No.
105
What is the Beta mode (ground mode), when power levers are aft of flight idle?
Blade angles are selected by the pilot with the power levers.
106
When do the L and R BETA lights on?
When pressure is adequate for full reverse ops
107
Propeller governing mode or constant speed mode is from what percent RPMs?
94-100%
108
In constant speed mode, blade angles on the props vary how?
To maintain selected RPM
109
Propeller blade angle is controlled by?
Mechanical governor consisting of a speeder springs and a flyweight force
110
If the speeder spring exceeds flyweight force the prop is in what condition?
Underspeed condition. This causes pilot valve to move, pumping more oil into the hub, decreasing prop angle, and increasing RPM
111
If flyweight force exceeds speeder spring force, what condition is the prop in?
Overspeed condition. This causes the pilot valve to move returning oil to the gear case, increasing prop angle, and decreasing RPM.
112
What happens when you pull the ENGINE STOP AND FEATHER?
Closes the fuel solenoid valve and drains the prop of oil. This then feathers the prop and stops the engine.
113
Holding the power levers in reverse when the engine isn’t running and holding the UNFEATHERING TEST does what?
Puts the propeller on the start locks.
114
Will pressing the START switch in air actuate the unfeathering accumulator?
Yes. When the weight is off of the squat switch, the start button will actuate the unfeathering pump allowing an air start.
115
Why do we have start locks for the propellers?
Produce the minimum resistance to start acceleration.
116
How are the start locks released?
Released for taxi by momentarily holding the power levers in reverse, centrifugally releasing the pins
117
When does NTS occur?
When the propeller is driving the engine.
118
What will the NTS do?
Move the prop towards feather until the engine is driving the prop, and moving it to a flatter pitch.
119
How long will the NTS cycle continue?
Until the pilot pulls the ENGINE STOP AND FEATHER
120
Ignition will activate until how long after NTS is deactivated?
30 seconds
121
When is it recommended to feather the propeller by?
30% so that it doesn’t windmill from 28 down to 18%.
122
The NTS Lockout system prevents windmilling propeller drag from being sensed as an engine failure during?
The landing rollout.
123
When the power levers are moved aft of flight idle, what happens to the NTS lockout valve?
Opens to drain oil from prop governor reset piston. This resets the prop governor 5% higher.
124
The resetting of prop governor will ensure what?
That maximum pressure will be available to the propeller blade angle.
125
When is the NTS test done?
Prior to the first flight of the day
126
What RPM do you use with the NTS test?
Low RPM
127
Stabilized RPM, during NTS test, should not exceed what percent?
94.5%
128
If the RPM exceeds 94.5%, what could be the two issues?
Either the propeller governor low setting is misrigged or the oil supply to the NTS system is malfunctioning.
129
Where should the NTS test be done?
While stopped or while on a long wide taxiway.
130
What does the syncrophaser do?
Matches the RPM of the slower engine to the faster engine
131
When power levers are aft of flight idle they control what?
Pitch of prop
132
When power levers are forward of FLT IDLE what do they control?
Manual fuel valve in the FCU.
More power = more fuel flow
133
Should you ever place the power levers aft of the FLT IDLE position in flight?
No.
134
What should you do before going full reverse?
Ensure Beta lights are on.
135
Should you ever place the speed levers to low with the power levers behind ground idle (in REVERSE)?
No. It may cause catastrophic damage from high EGT due to underspeed governor adding fuel to burner to prevent low RPM.
136
CAWI dilution ratio
40% methanol 60% distilled water
137
Max amount of CAWI
16 gal
138
Minimum CAWI for use?
8 gal
139
How heavy is the CAWI when full?
128 lbs (8 lb/gal.)
140
If the AWI PUMP ON light illuminates, what does this mean?
The test has failed and CAWI can’t be used for takeoff.
141
What % RPM must the engine be at for CAWI to be used?
Above 90%
142
An immediate rise of how much %torque can you expect with use of CAWI?
30-35%
143
When do you turn CAWI off?
400 AGL or obstacle clearance.
144
How much %torque will you lose when CAWI is turned off?
35%
145
What happens if the essential bus fails with CAWI?
It’ll auto transfer to the opposite essential bus.
146
Max time limit for CAWI use?
5 min
147
Max torque with CAWI?
110%
148
Max EGT with CAWI?
650dC
149
CAWI may not be used if fluid had been exposed to ambient temperature below what in the preceding hour?
-24dC
150
What %difference do you need to be within to turn on the syncrophaser?
0.4%
151
How long should you hold the stop button for complete fuel purging during a normal shutdown?
5 seconds
