PTM Ch. 7 Powerplant Flashcards
What kind of engine do we have?
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.
What reduces the engine RPM from 41,730 to 1591?
Planetary gear box
What does stage 1 in the engine represent?
Ambient conditions outside the engine.
What does stage 2 represent?
Compressor inlet
What does stage 3 represent?
Compressor discharge
What does station 4 represent?
Turbine inlet
What does station 5 represent?
Turbine discharge or exhaust
What are the six accessories driven by the reduction gear?
- Fuel control and engine driven fuel pumps
- Hydraulic pump
- Starter-generator
- Tach generator
- Propeller governor
- Oil pump
What is the compression ratio?
10:1
What portion of the compressor discharge air is used to support actual fuel combustion?
1/3
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?
2/3
The combustor is an annular, reverse flow type with how many duplex nozzles and how many igniter plugs?
10 duplex nozzles
2 igniter plugs
What portion of turbine power is applied to the propeller shaft through the reduction gear?
1/3
What portion of the power generated by the turbine is used to drive compressor?
2/3
Below what percentage is EGT compensated?
80%
Above what percentage is EGT computed?
80%
What will happen to engine instruments if their respective essential bus fails?
Auto transfer to opposite essential bus.
What are the three functions of the SRL?
- Engine speed switching functions
- Automatic start fuel enrichment
- Single red line EGT computation
The SRL has automatic control of the start sequence from what percentages?
10-60%
SRL does EGT COMPUTATION above what percentage?
80%
When does CAWI operation and EGT temperature limiting happen from the SRL?
Above 90%
What are the five inputs to the SRL computer?
- 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
If you lose your SRL where do you find the numbers to fly off of?
Look at the numbers on the cabin ceiling
What are the 5 signs your SRL is malfunctioning?
- 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
If the SRL needs to be deferred, review the following 3 documents:
- MEL
- AFM Chapter 3A
- AFM Supplement 1A
If the SRL is inop what will be different about the engine start?
It’ll be a manual start
Will temperature limiting be available without an SRL?
No
Will CAWI be available without an SRL?
No
What RPM is needed for the temperature limiter?
Above 90%
Why would the “bypass open” annunciator come on for?
Fuel bypass valve opens to circumvent fuel and keep EGT below 650 dC.
What do you do on the takeoff roll if the “bypass open” comes on?
Reduce the power levers until the the annunciator turns off.
Should you test the Temp Limiter in flight?
Negative. Engine flameout may result.
What is the maximum altitude for prolonged operation with the bypass valve failed open?
15000’
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
Can we takeoff with the Bypass Valve failed open position?
No
What 4 things does engine oil do?
- Cooling and lubricating of main engine bearing and reduction
- Oil for propeller control
- NTS - negative torque sensing
- Unfeathering pump
What’s the approved oil?
BP2380
When is the best time to check the oil quantity?
Within 10 minutes of shutdown
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%.
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.
How many scavenge pumps do we have for oil?
3
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
The gear case scavenge pump oil passes through what on the way back to the tank?
A fuel heater and oil cooler
Minimum oil pressure?
40 psi
> 23000’ = 50 psi
Oil pressure annunciator will illuminate when?
If oil pressure drops below 40 psi or 50 psi above 23000’.
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.
What does the CHIP DET annunciator mean?
Indicates metal particles in the oil
Ignition consists of what?
Engine mounted exciter and 2 igniter plugs located in combustion chamber
Ignition is powered by what?
Respective essential bus AUTOMATICALLY transferable to the opposite side.
What does the AUTO on the ignition switch do?
Allows the SRL to control during start (10-60%), ignition if NTS is activated
What does the CONT on ignition switch do?
Continuous ignition
When should you use continuous ignition?
- <5dC with visible moisture
- Contaminated runway
- Turbulence
- Precipitation
What is the OFF on the ignition switch for?
Off but will permit a normal start (not normally used)
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.
The vent valve in the oil system opens when?
When you press the start button
Why do we need a vent valve in the oil system?
To reduce resistance on oil flowing through the system on startup.
What can the unfeathering pump be used for?
- Put props on start locks if the props were feathered on the ground
- Used for unfeathering during air start.
Engine fuel system includes what seven items?
- Engine driven high pressure pump
- Engine driven low pressure pump
- Fuel control unit (FCU)
- Fuel solenoid valve
- Flow divider
- Fuel manifolds
- Primary and secondary fuel nozzles
What does the fuel control unit do?
Meters the correct amount of fuel to the nozzles
What are the inputs to the FCU?
- Power and speed lever positions
- Altitude and temperature via P2T2 probe (compressor inlet)
- Engine RPM
- Compressor discharge pressure P3