Propulsion Flashcards
1
Q
What is the purpose of the engine cowling?
A
Protect engine components, decrease drag, and provide engine air intake
2
Q
What kind of engine does the T-6 have?
A
PT-6A-68 free turbine, reverse flow design, turboprop
3
Q
What does Free Turbine refer to?
A
The compressor and power turbines are not physically connected. Air movement from one turbine to the other provides power to the propeller
4
Q
What does Reverse Flow Design refer to?
A
The flow of air through the engine. Air enters at the rear and moves forward during the combustion cycle
5
Q
What three elements are necessary for engine operations?
A
Air, fuel, and heat
6
Q
What are the major sections of the engine?
A
Accessory compartment, gas generation section, and power turbine section
7
Q
What items are found in the accessory compartment?
A
Accessory gearbox, oil tank, starter/generator, and battery
8
Q
What turns the compressor turbine and compressor initially?
A
The starter
9
Q
What is contained in the gas generation section?
A
Compressor inlet, compressor, combustion chamber, compressor turbine
10
Q
Where does inlet air flow into first?
A
Compressor inlet
11
Q
What is inlet air compressed by?
A
Four-stage axial flow compressor and single stage centrifugal flow compressor
12
Q
Where does air go after the compressor?
A
Combustion chamber
13
Q
What happens in the combustion chamber?
A
Compressed air is mixed with fuel and ignited
14
Q
What drives the compressor turbine?
A
Expanded gasses from the combustion chamber
15
Q
What components are in the Power Turbine Section?
A
Power turbine, exhaust case, reduction gearbox, propeller shaft
16
Q
What is the purpose of the Power Turbine Section?
A
Produce horsepower from the gasses generated by the gas generation section
17
Q
What drives the reduction gearbox?
A
The power turbine
18
Q
What drives the propeller shaft?
A
The reduction gearbox
19
Q
What components are in the Engine Exhaust System?
A
Exhaust ports and exhaust stacks
20
Q
What happens to the air after it comes off the power turbine?
A
It moves through the exhaust ports, followed by the exhaust stacks
21
Q
What kind of ignition does the T-6 use?
A
A dual spark ignition system
22
Q
What does the starter provide?
A
Initial air flow
23
Q
What does the Fuel Management Unit (FMU) provide on startup?
A
Fuel (duh)
24
Q
What does the ignition system provide on startup?
A
Initial heat source
25
What components make up the Ignition System?
An ignition exciter, two high voltage igniter cables, and two spark igniters
26
What does the ignition exciter receive to create a spark?
A low voltage input signal from the battery bus
27
What does the ignition exciter do with the input signal?
Transforms it into a high voltage output signal?
28
What do the ignition cables do?
Carry the high voltage signal to the spark igniters
29
What do the spark igniters do?
Provides a spark to the air/fuel mixture in the combustion chamber
30
What happens when the ignition switch is set to NORM and the starter switch is moved to AUTO/RESET?
The igniters will initiate
31
What does the Power Management Unit (PMU) do during startup?
Enerrgize and de-energize the igniters
32
Which annunciator lights up during the engine start sequence?
Green IGN SEL
33
What provides power for the ignition system?
The circuit breaker labeled IGN, located on the battery bus CB panel in the front cockpit
34
What does the PCL do?
Controls fuel flow to the engine
35
What is the PCL connected to mechanically and electrically?
The Fuel Management Unit
36
What three positions does the PCL have?
OFF, IDLE, and MAX
37
Where do you move the PCL to for start?
Between OFF and IDLE, when the green ST READY annunciator illuminates
38
What prevents inadvertent engine shutdown?
PCL cutoff gate
39
Where is the Power Management Unit located?
Under the engine in the accessory compartment
40
What does the Power Management Unit do?
Processes power requests from the PCL and keeps engine and propeller within operating limits
41
What does an amber PMU STATUS annunciator in flight mean?
Indicates a fault in either of, or a mismatch between the weight-on-wheels switches. The PMU will not revert to ground mode upon landing
42
What accompanies a PMU STATUS annunciator?
Yellow MASTER CAUTION light and an aural tone
43
What does a red PMU FAIL annunciator mean?
The PMU is nonfunctional
44
What accompanies a PMU FAIL annunciator?
MASTER WARN and MASTER CAUTION, and an aural tone
45
Where does power for the Power Management Unit come from?
A Permanent Magnet Alternator mounted on the reduction gearbox
46
What does the Permanent Magnet Alternator provide to the Power Management Unit?
32 VAC, which the PMU converts to DC
47
If the Permanent Magnet Alternator fails, where does the Power Management Unit get power?
From the 28 VDC battery bus
48
Where is the starter/generator located at?
Attached to the accessory gearbox
49
What is the accessory gearbox attached to?
The compressor section via a shaft
50
During engine start, what does the starter/generator do?
The starter motor turns the compressor section. This generates air flow and compression until the engine starts and is able to run at idle speed
51
What does the starter/generator do after engine start?
Becomes a generator, which provides 28 VDC to many aircraft systems, and charges battery and aux battery to 24 VDC
52
What three positions does the starter switch have?
AUTO/RESET, NORM, and MANUAL
53
How is power provided for the starter?
A circuit breaker labeled START on the battery bus C/B panel
54
What is the purpose of the oil system?
Provides a steady flow of filtered oil to the engine bearings, reductions gears, accessory drives, and propeller
55
What components make up the oil system?
Pressure system, scavenge system, and cooling system
56
How is oil pressurized?
The pressure pump
57
What ensures oil can flow, even during inverted or negative G flight?
There is a normal pickup in the center of the oil pump, and an inverted pickup near the top of the tank
58
What does the scavenge system do?
Returns oil to the tank after being used in the bearings, reductions gears, accessory drives, and propeller
59
What does the oil system use to scavenge oil back to the tank?
Several pressure and scavenge pumps throughout the oil system
60
What does the oil cooler do?
Cools the oil before it's returned to the oil tank
61
What filters the oil?
There is a main oil filter in the oil tank. There are also oil strainers in the power, compressor, and accessory drive areas
62
What happens if the mail oil filter gets clogged?
The oil travels through a filter bypass valve that allows unfiltered oil to continue lubricating the engine
63
Where is the chip detector located at?
In the reduction gearbox
64
What does the chip detector do?
Detects metallic particles in the oil and warns pilot of possible gear damage
65
What happens if the chip detector detects metal particles?
Red CHIP annunciator illuminates, MASTER WARNING illuminates, and an aural tone sounds
66
What is the purpose of the Signal Conditioning Unit (SCU)?
Illuminates the central warning system under certain oil pressure conditions
67
What pressure should oil be during steady state operations?
90 to 120 psi
68
What should oil pressure be during aerobatic flight?
40 to 130 psi
69
When at IDLE, when will the OIL PX amber annunciator illuminate?
Between 15 to 40 psi
70
When above IDLE, when will the OIL PX amber annunciator illuminate?
Between 40 to 90 psi for 10 seconds
71
When at IDLE, when will the OIL PX red annunciator illuminate?
Below 15 psi, or when between 15 to 40 psi for more than 5 seconds
72
Where is power for the oil system transducer provided from?
The OIL TRX circuit breaker on the battery bus circuit breaker panel in the front cockpit
73
What is the purpose of the propeller?
To provide thrust
74
What kind of propeller does the T-6 use?
Four blade, variable pitch, constant speed
75
What two components controller propeller speed (Np)?
The Power Management Unit and Propeller Interface Unit
76
What speed is the propeller held to?
2,000 rpm
77
How are varying levels of thrust provided?
By adjusting the propeller pitch
78
What altitude is 100% torque available for?
From sea level to between 12,000 and 16,000 MSL
79
What happens to torque above 16,000 MSL?
There will be a decrease in max torque
80
What is the propeller driven by?
The power turbine, through the reduction gearbox
81
What speed is the power turbine spun at?
30,000 rpm
82
What is propeller speed (Np) measured by?
The phase shift torque probe
83
What monitors the phase shift torque probe?
The Power Management Unit
84
What directs the Propeller Interface Unit to maintain propeller rpm?
The Power Management Unit
85
What does the Propeller Interface Unit use to restrict rpm?
An electronic governor
86
What happens if the electronic governor fails?
There is a backup mechanical governor
87
What does the backup mechanical governor hold the propeller to?
106% torque, or 2120 rpm
88
What changes propeller pitch?
Changes in oil pressure
89
What are the three basic blade pitch angles base upon?
The angle between the plane of rotation and the chord line of the propeller
90
What are the three basic pitch conditions?
Feathered, high pitch (coarse), and low pitch (flat or fine)
91
What is the default condition of the propeller?
The feathered position
92
What does the feathered position provide?
The least amount of drag and no thrust
93
What pitch will the propeller usually be in?
High pitch
94
What does a low pitch propeller provide?
Some thrust and the most drag
95
What controls the oil flow to the propeller?
The Propeller Interface Unit
96
What happens as oil pressure is increased in the propeller?
The blades move from the feathered position to high pitch, then to low pitch
97
What PCL position causes the prop to feather?
OFF
98
What happens if there is any residual oil pressure in the system if the engine fails?
The prop might not feather
99
When the engine fails and the PCL is placed in off to feather, what happens in the system?
Two valves are activated in the Propeller Interface Unit, the feather dump solenoid valve, and an oil pressure release valve. This allows the prop to feather
100
What circuit breaker controls the feather dump solenoid valve?
The PROP SYS circuit breaker on the battery bus circuit breaker panel
101
Where is the Engine Data Manager located?
In the left avionics bay
102
What engine related tasks does the Engine Data Manager do?
Drives primary, alternate, and engine/system displays, and illuminates advisory, caution, or warning annunciators when appropriate
103
What non-engine related tasks does the Engine Data Manager do?
Fuel balancing, fuel quantity indications, activation of nose wheel steering annunciator, display of DC volts, amps, hydraulic pressure, cockpit pressure altitude, and cockpit pressure differential
104
What provides power to the Engine Data Manager?
Two EDM circuit breakers. One on the battery bus circuit breaker panel, and one on the generator bus circuit breaker panel in the front cockpit
105
What is the Primary Engine Data Display (PEDD)?
An electronic instrument display that presents engine information from the Engine Data Manager
106
What processes the information from various sensors around the engine?
The Power Management Unit
107
What monitors engine parameters and passes the information to the Primary Engine Data Display?
The Engine Data Manager
108
What does the Primary Engine Data Display do during abnormal engine operations?
Changes the color of the scales
109
What is the normal operating range color?
White or green
110
What is the cautionary operating range color?
Amber
111
What is the exceeding operating limits color?
Red
112
What information is provided on the Primary Engine Data Display?
Torque, Inter-Turbine Temp, Propeller RPM (Np), and Indicated Outside Air Temp (IOAT)
113
What are the in-limits for torque?
0 to 100%
114
What are out-of-limits for torque?
Anything more than 100%
115
What does ITT indicate on the Primary Engine Data Display?
The temp between the compressor turbine and power turbine
116
What are ITT operating limits during start sequence?
400° to 1000°C
117
After start sequence, what are the ITT operating limits?
400° to 820°C
118
What are out-of-limits for ITT?
Above 820°C
119
What does the N1 indication on the Primary Engine Data Display indicate?
Gas generator speed
120
What are normal operating limits for N1?
60 to 104%
121
What are out-of-limits readings for N1?
Above 104%
122
What are the ground operation limits for Np?
0 to 61% and 81 to 100%
123
What percentage of Np is prohibited on the ground?
62 to 80%
124
What is out-of-limits for Np in flight?
Above 102%
125
What circuit breaker controls the PEDD?
PRI ENG DIS on the generator bus circuit breaker panel
126
What does the Alternate Engine Data Display do?
Provides each cockpit with a backup visual indication of engine operations
127
Except for torque, what displays information for the Alternate Engine Data Display?
The Engine Data Manager
128
What does the Alternate Engine Data Display show?
Raw ITT, Torque, Gas Generator Speed (N1), Cockpit pressure altitude, Cockpit differential pressure, fuel flow, and fuel quantity
129
What happens if your cockpit altitude exceeds 19,000 feet?
The Cockpit Alt information on the AEDD is boxed in yellow, and an amber CKPT ALT annunciator illuminates, along with an aural tone
130
What happens if the differential pressure exceeds 3.9 to 4.0?
The differential pressure readout is outline in a red box, and a red CKPT PX annunciator is illuminated, along with an aural tone
131
How is the AEDD powered?
ALT ENG DIS circuit breaker on the battery bus circuit breaker panel
132
What does the engine/system display show?
Oil, hydraulic, and electrical system data
133
What are the normal operating limits for oil temp?
10° to 105°C
134
What are the cautionary operating limits for oil temp?
105° to 110°C
135
What is the out-of-limits readings for oil temp?
Above 110°C
136
What powers the engine/systems display?
ENG SYS DIS on the generator bus circuit breaker panel
137
What does the Firewall Shutoff Handle do?
Shuts of hydraulic fluid and fuel flow to the engine, as well as bleed air flow from the engine
138
What provides power for the Fire #1 warning system?
FIRE 1 circuit breaker panel on the battery bus circuit breaker panel
139
What provides power for the Fire #e warning system?
FIRE 2 circuit breaker panel on the generator bus circuit breaker panel
140
What are possible indications of a Hot Start?
- High/rapidly rising ITT
- Lower N1
- Lower Np
141
What are possible causes of a Hot Start?
- PMU failure
- FMU failure
- Incorrect air/fuel mixture
- Low battery
142
What are possible indications of a Hung Start?
- Slow rising ITT
- Lower N1
- Lower Np
143
What are possible causes of a Hung Start?
- PMU failure
- FMU failure
- Incorrect air/fuel mixture
- Ignition system failure
- Starter failure
- Low battery
144
What are possible indications of a No Start?
- No ITT indication
- Lower N1
- No Np indication
- No torque indication
145
What are possible causes of a No Start?
- PMU failure
- FMU failure
- Starter failure
- Ignition system failure
- Incorrect air/fuel mixture
146
What are initial indications of Engine Failure In-Flight?
- Loss of power and airspeed
- Rapid decay of N1, torque and ITT
- MASTER WARN light and tone
- Propeller moves toward feather
147
What are accompanying indications of Engine Failure In-Flight?
- Rapidly decreasing ITT, Np
- Lower than normal oil pressure
- Engine noise
- GEN, FUEL PX, OIL PX, OBOGS FAIL annunciators
- Possibly PMU FAIL and CKPT ALT annunciators
148
What are possible causes of Engine Failure In-Flight?
- Fuel starvation
- Mechanical failure
- Compressor stall
149
What should you do if you experience an engine failure in-flight?
Proceed with appropriate emergency procedure
150
What are possible indications of a PMU Failure?
- Power step change
- PMU Fail and PMU STATUS annunciators
- MASTER WARN light
- Aural tone
151
What are possible causes of a PMU Failure?
- System failure
| - System malfunction
152
What is the appropriate procedure for a PMU Failure?
Proceed with PMU failure procedure
153
What are possible indications of Uncommanded Power Changes/Loss of Power?
- Reduction in power/thrust
- Lower than expected fuel flow
- Uncommanded decrease in N1
- High raw ITT on AEDD
- With oil/engine/fuel system contamination, additionally:
- Power surges
- Uncontrollable high power
154
What are possible causes of Uncommanded Power Changes/Loss of Power?
- Engine rollback due to PMU scheduling
| - Oil/engine/fuel system contamination
155
What are possible indications of Uncommanded Feather?
- Rapid loss of power
- High torque
- Lower Np
- Possible PMU FAIL/PMU STATUS annunciators
- Engine vibration
- Engine noise
156
What are possible causes of Uncommanded Feather?
- Feather dump solenoid malfunction
| - Loss of oil pressure to propeller pitch control mechanism
157
What are possible indications of Prop Sleeve Touchdown?
- Np fluctuations
- Increasing torque
- Decreasing thrust
- Engine vibrations
- Possible CHIP detector warning light
158
What are possible causes of Prop Sleeve Touchdown?
Loss of oil pressure to propeller pitch control mechanism from momentary contact between oil transfer sleeve and propeller shaft
159
What is the appropriate procedure for Pro Sleeve Touchdown?
- Proceed with uncommanded propeller feather procedures
160
What are possible indications of Engine Fire In-Flight?
- FIRE annunciator
- MASTER WARN light
- Aural tone
161
What is the FEVER check for Engine Fire?
- Fluctuating oil pressure, oil temp, or hydraulic pressure
- Excessive turbine temp
- Visual indications (smoke or flames)
- Erratic engine operation
- Roughness or vibration
162
What are possible cause of Engine Fire In-Flight?
- Fuel or oil leaks
| - Fire getting outside of engine
163
What procedure should you take for Engine Fire In-Flight?
Proceed with fire warning in-flight procedure
164
What does an amber PMU STATUS annunciator after landing mean?
The PMU has accommodated a fault that needs to be cleared by maintenance
