Power Plant Flashcards
(156 cards)
1
Q
What type of engines power the 234
A
Two AVCO Lycoming AL 5512 engines
These engines are now believed to be Honeywell.
2
Q
What is the maximum continuous rating for the engines in SHP?
A
2,975 SHP
3
Q
What is the FAA OEl 30 min rating for the engines in SHP?
A
Up to 4,355 SHP
4
Q
How much fuel do the engines burn per hour?
A
Approximately 200 gal/hr per engine
5
Q
What is the weight of fuel consumed per hour per engine in pounds?
A
1,400 lbs per hour per side
6
Q
How many mounts are used for engine
A
Three mounts: 2 forward and 1 aft
7
Q
What type of starter motor is used for the engines?
A
Hydraulic start motor from the utility hydraulic system
8
Q
What function does bleed air from the compressor serve?
A
Cooling, pressurizing seals, fuel control system, bleed band actuation, and pressurizing reservoirs for flight control hydraulic systems
9
Q
What safety systems are provided for the engines?
A
Fire detection, warning, and extinguishing systems
10
Q
What does the fuel control unit on each engine regulate?
A
N1 and N2 speed and response to power demanded and rotor speed selected
11
Q
What is N1 varied according to?
A
Load on rotors to keep N2 and rotor speed constant
12
Q
What type of lubrication system does each engine have?
A
Self-contained lubrication system
13
Q
What type of engine is the AL 5512 gas turbine engine?
A
Direct drive turbo-shaft engine
14
Q
How many major sections are there in the AL 5512 gas turbine engine?
A
Six major sections
15
Q
List the major sections of the AL 5512 gas turbine engine.
A
- Air inlet
- Accessory drive
- Compressor
- Diffuser and combustion
- Gas producer
- Power turbine and exhaust
16
Q
What is the role of the power turbine shaft in the AL 5512 engine?
A
Drives output at the front of the engine
17
Q
Fill in the blank: The AL 5512 engine has a _______ combustion system.
A
[annular combustion system]
18
Q
True or False: The power turbine shaft is positioned coaxially within the compressor shaft.
A
True
19
Q
What are the two main sections of the engine?
A
Gas producer section and power turbine section
20
Q
How is air processed during engine start?
A
Air goes through inlet, is compressed, flows through diffuser, mixed with fuel, and ignited
21
Q
What drives the N1 and N2 wheels in the engine?
A
Hot gas expansion from combustion chamber
22
Q
What is the purpose of the air inlet housing?
A
It encloses various components including output shaft support housing and accessory drive gearing
23
Q
What supports the outer wall of the air inlet area?
A
Four hollow support struts
24
Q
Where is the engine oil supply tank located?
A
Within the cavity formed by the inner housing
25
What does the starter drive connect to?
The compressor rotor by a shaft and gearing
26
Where is the overspeed governor mounted?
At the 11 o'clock position on the housing
27
What type of compressor does the compressor housing and vane assembly enclose?
7 stage axial compressor and a single stage centrifugal compressor
28
What is the function of the bleed band in the compressor housing?
It allows air to escape from the 6th stage to avoid compressor stall at low power settings.
29
What does the compressor rotor consist of?
7 rotor discs, 7 spacers, and a centrifugal impeller
30
How are the stub shafts of the rotor supported?
By no 1 and no 2 bearings
31
What is the role of the pneumatic actuator assembly in the AL5512?
Controls airflow velocity by tightening or loosening a metal band over vent holes
32
What has been disconnected from the engine anti-icing system?
Seventh stage bleed air
33
What material is the air diffuser made of?
Stainless steel
34
What do the diffuser vanes do?
Convert velocity energy into pressure prior to combustion
35
What design does the combustion route of the engine utilize?
Reverse flow annular design
36
What does the combustion chamber housing attach to?
It attaches forward of the air diffuser housing circumference
37
Fill in the blank: The inlet housing provides mounting for the _______.
Torquementer junction box
38
True or False: The compressor rotor is connected to the power turbine shaft.
False
39
What connects to tubes in the air diffuser to provide pressure and scavenge oil?
External oil lines
## Footnote
These lines connect to the No 2 bearing housing.
40
Where is oil pressure measured in the engine?
At a tee just below the No 2 bearing strainer housing externally on the air diffuser.
41
What components make up the combustion chamber?
* Chamber housing
* Vanes
* Liner
* Two drain valves
42
How does air flow from the compressor to the combustion chamber?
Air flows through the outer air case to the rear of the assembly and changes direction 180 degrees.
43
What is the purpose of the slots cut in the flame tube?
To allow the right amount of air into the tube to maintain the proper fuel/air mixture and cooling.
44
What type of burners are used in the combustion process?
28 atomizer type burners.
45
What happens to gas during combustion in the combustion chamber?
Rapid expansion of gas causes it to accelerate forward and then reverse flow 180 degrees before exiting.
46
What is the function of the combined dump valve and flow divider?
To allow excess fuel to drain from the combustion assembly when the engine is stopped.
47
What type of turbine system is the gas producer turbine (N1)?
A two stage axial flow air cooled system.
48
What components are coupled together in the gas producer turbine?
Two turbines mounted on the rear end of the compressor shaft.
49
What does the power turbine (N2) do?
Takes power from the two stage axial flow assembly and transmits power forward through the compressor shaft.
50
What is measured at the stage three nozzle section?
Power turbine temperature.
51
What drives the accessory drive gearbox?
Shafts located within the 6 o'clock strut of the air inlet housing.
52
Which components does the bottom section of the accessory drive shaft drive?
* N1: Fuel pump
* Oil Pump and N1 tach
* FCU
* N2: N2 tach
* Overspeed generator
* FCU Speed sensor
53
What is the purpose of the chip detector in the gearbox?
To detect metal particles in the oil.
54
How does engine starting occur?
By energizing starter and ignition systems.
55
What ignites the start fuel in the combustion chamber?
Four spark plugs.
56
Where does metered main fuel go after leaving the fuel control?
It passes through the heat exchanger and then to the high pressure side of the fuel preheater.
57
What does the flow divider provide?
Primary and secondary fuel flow separation to the 28 air blast fuel nozzles.
58
Fill in the blank: The air blast fuel nozzles introduce fuel into the _______.
combustion chamber.
59
What is the primary function of the Engine Fuel Control?
Automatically controls N1 and N2 speed in response to pilot-selected controls.
60
What does the Engine Fuel Control vary to manage engine performance?
The amount of fuel to the engine fuel nozzle.
61
What does the automatic acceleration limiter protect against?
Turbine over temperature or compressor surge during accelerations.
62
What is the purpose of the deceleration limiter?
Protects against flameout during deceleration.
63
What does the Engine Fuel Control include?
* Single element fuel pump
* Gas producer speed governor
* Power turbine speed governor
* Acceleration-deceleration control
* Fuel flow limiter
* Fuel control fuel shutoff valve
* Main metering valve
64
Where are the N1 and N2 levers located?
On the fuel control.
65
What restricts the output power of the engine?
Max fuel flow to the gas producer.
66
How is the max gas producer rotor speed set?
By the ECL in the cockpit.
67
What does the ECL electromechanically position?
The gas producer lever which controls the fuel control fuel shutoff valve.
68
During flight, what mode is the ECL in?
FLIGHT.
69
What regulates output speed during flight?
N2 governor.
70
What determines the position of the main metering valve?
* N1 governor
* N2 governor
* Acceleration-deceleration control
* Fuel flow limiter
71
What happens when multiple governors demand fuel flow?
The governor demanding the least fuel flow overrides the others.
72
What does the N2 governor sense and regulate?
Speed of power turbine and amount of fuel to gas producer.
73
What is the maximum allowable output speed variation from min to full load for the N2 governor?
10%.
74
What minimizes droop in the system?
A droop eliminator linked to collective control.
75
What are the variable inputs to the Fuel Control Unit (FCU)?
* T2 (ambient temp)
* P3 (air pressure prior to combustion)
* N1 speed sensing
* N2 speed sensing
76
What does the FCU output to maintain engine operation?
A metered fuel supply.
77
What is the governing factor within the normal flight range?
N2.
78
True or False: The demand by the ECL when set to FLIGHT is always for full gas generator power.
True.
79
What might cause transient droops in engine performance?
Load changes.
80
Fill in the blank: The FCU is a computer with ______ variable inputs.
6.
81
What is the effect of atmospheric conditions on the FCU?
It adjusts the output based on T2 and P3.
82
What type of oil system is used for each engine?
Self-contained oil system
## Footnote
Each engine has its own oil system with the tank integrated into the air inlet housing.
83
What components are included in the engine oil system?
Engine driven pump assembly with:
* One pressure pump
* Two saving pumps
## Footnote
The system is designed to supply oil effectively to the engine.
84
Where is the gravity filler port located in the oil system?
On top of the tank
## Footnote
The filler port includes an indicator on the left side of the inlet housing.
85
What is the capacity of the oil tank?
3.75 US gallons
## Footnote
This is the total volume of oil the tank can hold.
86
What does the ENG OIL LEVEL annunciator indicate?
When oil level falls to 1.6 gallons
## Footnote
This alert informs the pilot of low oil levels.
87
What does the ENG OIL PRESS LOW light indicate?
When pressure is less than 15-19 PSI
## Footnote
This warning signals low oil pressure in the system.
88
What type of display is used for oil pressure and temperature?
Dual pointer
## Footnote
There are dual pointers for both pressure and temperature on the panel.
89
What is the path of oil from the tank to the engine?
Oil flows from:
* Pressure pump
* Through a filter
* To an oil cooler
* Then to the engine
## Footnote
The path ensures that the oil is clean and at the right temperature before entering the engine.
90
What sections of the engine are lubricated by the oil system?
Oil lubricates:
* Front section (including engine accessories gearbox and front bearings)
* Rear section of the engine
## Footnote
This dual lubrication system is crucial for engine operation.
91
What protects the oil system from overpressure?
Pressure relief valve
## Footnote
This component protects the system by releasing pressure when necessary.
92
What is the function of the cooler bypass valve?
Ensures adequate circulation at low temperatures or if the cooler is blocked
## Footnote
This valve helps maintain oil flow to the engine under various conditions.
93
How does oil drain from the engine accessories drive gearbox?
Front oil drains into the accessories drive gearbox
## Footnote
This process helps return oil to the reservoir.
94
What assists in returning oil from the rear section of the engine?
Paddle type scavenge oil pump
## Footnote
This pump helps return oil to the reservoir efficiently.
95
What happens to oil draining from the rear section bearings?
It is passed to the engine accessories drive gearbox
## Footnote
This oil is then returned to the reservoir with the help of a paddle pump.
96
What is the final destination of the oil returned by the scavenge pump?
Passages within the walls of the air intake
## Footnote
The oil is cooled by inlet air before draining.
97
What happens to scavenged oil during a cold start?
A valve opens to allow scavenged oil to bypass the passages and return directly to the tank.
## Footnote
This ensures proper lubrication during initial engine operation.
98
What is the function of the vent system in the engine lubrication system?
It bleeds air/oil vapor from the accessories gearbox and the tank to the engine starter gearbox where it is separated by a centrifuge.
## Footnote
Air is vented and oil is returned to the tank.
99
What does the ENG CHIP DET annunciator indicate?
It indicates the presence of metal chips in the accessory gearbox.
## Footnote
This is monitored by a chip detector.
100
How does rear bearing oil from no 4 and no 5 bearings interact with scavenge oil?
They flow separately into a housing containing dual chip detectors without cockpit indications.
101
What are the positions of the Engine Condition Levers (ECL) on the overhead panel?
STOP, GROUND, and FLIGHT.
## Footnote
A rotor brake arming lever is also colocated here.
102
What must occur before transitioning from GROUND to FLIGHT on the ECL?
The rotor brake must be disarmed.
103
What does the ECL control in the event of high side N2 governor malfunctions?
It can be used to control power output.
104
What happens if the ECL is pulled out of FLIGHT?
It changes N2 control over to N1.
105
What mechanism holds the actuator in a selected position if electrical power is lost?
A built-in mechanical brake holds the actuator at its last selected position.
106
From where is the electrical power for the ECL system sourced?
From No. 1 DC essential bus via the ENG NO. 1 COND CONT circuit breaker on No. 1 PDP for engine 1 and similarly for engine 2.
107
What is the role of the N1 actuator in the engine lubrication system?
It mechanically operates a lever to control the fuel shutoff valve and operating speed of the gas producer.
108
Fill in the blank: The chip detectors in the accessory gearbox illuminate the _______ annunciator.
ENG CHIP DET
109
True or False: The chip detectors in the housing provide cockpit indications.
False
110
What is the purpose of the logic N2 Power Turbine Control System?
It manages the control of the power turbine.
111
What regulates power during flight?
N2 governor
112
What component adjusts RPM by positioning the N2 power lever?
Fuel control unit
113
What is the function of the logic box in the N2 governor system?
Establishes beep trim position
114
What are the components of the electromechanical system for N2 governor?
* Engine trim switches on collective control heads
* Emergency engine trim switches on overhead panel
* Dual drop eliminator LVDT
* Power turbine control actuator and linkages
115
What is the purpose of the LVDT (droop eliminator)?
Minimizes lag in engine response to power changes
116
Where is the LVDT mechanically linked?
Lower portion of the flight control closet
117
What inputs does the logic control box analyze?
* Required fuel control position
* Position of the fuel control arm
* Collective head beep trim setting
* Mx adjustments
* N2 actuator position
118
What is the response rate from the control boxes to collective changes?
Faster than 50 degrees per second
119
What is the normal beep rate for the system?
3 degrees per second
120
What does the power turbine control actuator consist of?
* Motor
* Gear reduction train
* Sliding friction dampener
* RVDT
121
What feedback signals does the RVDT provide?
Position of the actuator
122
What allows the pilot to adjust motor output when ECL is in the fly position?
Beep trim switches on the collective
123
What happens when the ECL is in the fly position?
Full power is available and power demand is sensed automatically
124
What are the two modes of the emergency trim system?
* Auto
* Manual
125
What occurs in MAN mode for the emergency trim system?
Control box is disabled, and emergency trim switches control it
126
What voltage do the emergency trim switches use?
28 volt DC
127
What must be done before resetting the beep trim switch to AUTO?
* Retard affected engine ECL from FLIGHT
* Beep down the appropriate normal beep trim
* Select AUTO on the EMERGENCY ENG TRIM panel
128
What are the steps to reset the logic system to beep nominal?
* Select auto/man to man
* Pull 5 amp EMER TRIM circuit breaker
* Wait a minimum of 15 seconds
* Reset the EMER TRIM CB
* Reset auto/man to AUTO
129
What is the power source for emergency trim switches?
28 v DC from NO. 1 emergency bus
130
What system is described as part of the ignition and start system?
131
What is the primary power source for the ignition system?
Hydraulic power from the utility system
## Footnote
The ignition system includes components such as ignition exciter, igniter plugs, coil and cable assembly, hydraulic starter, start solenoid valves, hydraulic relief valves, and an engine start switch.
132
What components make up the ignition system?
* Ignition exciter
* Igniter plugs
* Coil and cable assembly
* Hydraulic starter
* Start solenoid valves
* Hydraulic relief valves
* Engine start switch
## Footnote
These components work together to initiate the engine start process.
133
What is the first step in the engine start sequence?
Place ECL in STOP
## Footnote
ECL stands for Engine Control Lever.
134
What happens after the engine start switch is set to MOTOR?
28VDC directed to the required engine, opening the start valve
## Footnote
This action allows 3350 PSI from the utility system to motor the starter and crank the engine.
135
What pressure is used to motor the starter during engine start?
3350 PSI from the utility system
## Footnote
This pressure is essential for cranking the engine.
136
What role does the utility isolation valve play during engine start?
Closes to isolate all utility subsystems
## Footnote
This isolation ensures the starter has full pressure for operation.
137
What is the purpose of removing power from certain systems during the start sequence?
To reduce the electrical load
## Footnote
Systems such as windshield anti-ice circuits, cabin heater/blower, avionics cooler fan, and fuel boost pumps are affected.
138
At what N1 percentage should the ECL be moved to GROUND?
10-15% N1
## Footnote
This step is part of the engine start procedure.
139
What happens when the engine start switch is set to START?
Allows 28V DC to the ignition unit and ignition coil
## Footnote
This action energizes the spark plugs and opens the solenoid valve for start fuel.
140
What should be monitored prior to releasing the start to MOTOR?
PTIT (Power Turbine Inlet Temperature)
## Footnote
The temperature should be monitored to ensure safe engine startup.
141
What is the purpose of continuing to motor the engine after reaching 50% N1?
To help with acceleration to 50% N1
## Footnote
Motor continues to turn to stabilize N1 during the start process.
142
What happens at 50% N1?
Switch to OFF, closes engine start valve, opens utility system isolation valve, turns off ENG START caution light
## Footnote
Start cross tie relay permits other engine to be started.
143
What is the purpose of the Overspeed Protection System?
Reduce engine power turbine speed if N2 goes over 114%
## Footnote
Includes overspeed harness, controller, fuel limiting valve, and power turbine magnetic speed pickups.
144
What triggers the fuel limiting valve in the Overspeed Protection System?
Signal from two tandem coil power turbine magnetic speed pickups when N2 reaches 114%
## Footnote
The controller powers the fuel limiting valve to reduce fuel flow to 310 lb/hr.
145
How does the Overspeed Protection System ensure reliability?
Uses separate digital and analog speed sensing channels that must both agree before actuation
## Footnote
This design provides high immunity to false actuation.
146
What do Fire Protection Systems provide?
Warning of fire or overheat in the engine or APU compartment
## Footnote
Also includes two extinguisher charges for engines and one for APU.
147
What happens when fire is detected in the Fire Protection System?
Handles illuminate and audible alert is activated
## Footnote
Pulling T-handles shuts off fuel valve and arms fire bottles.
148
How many circuits are there in the Fire Protection System?
Three circuits: two for each engine and one for the APU
## Footnote
Identical circuits for each engine ensure redundancy.
149
What is the function of the Engine Indicating Systems?
Display engine performance metrics such as torque and temperature
## Footnote
Includes dual electric torque meters, PTIT readings, and fuel pressure indicators.
150
What powers the Engine Indicating Systems?
Power comes from No 1 and No 2 AC essential bus for indicators
## Footnote
Inverters for reference signals come from No 1 DC essential bus.
151
Where are PTIT readings taken?
Between gas producer turbines and prior to power turbines
## Footnote
Ten thermocouples installed on each engine provide data.
152
What does the fuel pressure transducer do?
Feeds the indicator in the cockpit with fuel pressure data
## Footnote
Sensed at the input side of the engine fuel control.
153
What is the requirement for fuel temperature below 0°C?
Anti-icing additive must be added
## Footnote
This requirement is stated in FAR 33.67.
154
What does the engine monitor system display?
Shows TQ, PTIT, N1 or N2 for either engine
## Footnote
It can freeze a display for reading and record power checks.
155
How is the engine monitor system powered?
28 volt DC from No 1 DC bus and 115 volt AC from No 1 AC bus
## Footnote
Allows it to function in lieu of normal readouts if instruments fail.
156
What is the test feature of the engine monitor system?
Move knob to STBY, press test switch, rotate switch clockwise from STBY
## Footnote
Should show readings like 000, 011, 022, etc.
