Skyblue CBT propellor control Flashcards
what is the normal takeoff power setting?
2475SHP
what SHP does the automatic uptrim setting provide following an EFATO?
2750SHP
what components make up the two spool gas generator?
a high pressure and low pressure compressor powered by their respective turbines
how does the power turbine drive the propeller?
via a power turbine shaft which links to a propeller reduction gear box and then the propeller shaft
what does the intake design ensure?
uniform inward flow is supplied to the compressors
what are the 2 purposes of the S shaped design of the inlet?
- FOD removal (air is lighter so it goes up to the compressors while FOD is too heavy and goes down and overboard
- to divide the airflow into a primary flow for the engine and a secondary flow for the oil cooler
where is the accesory gearbox mounted?
at the top of the engine
what is the accesory gearbox driven by?
high pressure compressor shaft
what 3 components are driven by the accesory gearbox?
1 high pressure fuel pump
- oil pumps
- DC Starter/generator
what does the DC starter/generator drive during engine start?
accesory gearbox in order to accelerate the high pressure compressor rotor to the necessary speed
what 4 components does the propeller reduction gearbox connect to?
- propeller overspeed governer
- 115 volt ACW GENERATOR
- propeller valve module
- high pressure pump
engine 2 also connects to the prop brake
where is the fuel cooled oil cooler located?
aft of the propeller reduction gearbox
what kind of propeller does the ATR have?
Hamilton Standard 568F prop which is composite
what is the propeller driven by?
free power 2 stage turbine through the reduction gearbox
what powers the free power turbine?
exhaust gases
what is propeller pitch controlled by?
hydro mechanically controlled by a propeller valve module installed on the prop reduction gearbox
what changes the propeller pitch?
oil pressure from the lubrication system supplied by a feathering pump
how is the propeller feathered?
metered oil pressure is dumped
what does each PEC control? (6)
- PVM
- Phase sync of the props
- overspeed governor
- autofeather system
- alternate autofeather system
- power and condition levers
how does the PEC control the pitch change mechanism?
through 1 or 2 channels
how does the PEC select the correct prop speed
PEC calculates correct pitch using altitude and speed data and prop rotation data.
what does the PEC interface with to get altitude, speed and prop rotation data?
the EEC
WHAT DOES THE PROPELLER INTERFACE UNIT DO?
provides interfcae between the engine controls in the flight deck and the PEC
what `6 functions does the propeller valve module have?
- speed setting
- beta scheduling
- propeller feathering
- synchrophasing
- low pitch protection
- overspeed protection
what 4 components make up the propeller valve module?
- electro hydraulic valve
- protection valve
- feather solenoid
- rotary variable differential transducer (RVDT)
what does the electro hydraulic valve in the PVM do?
meters oil to the pitch change actuator and allows normal feathering of the prop
what is the protection valve in the PVM part of?
overspeed, lo speed protection systems and backup feathering protection
what is the feather solenoid a backup for?
the electro hydraulic valve
what does the RVDT do?
adjusts and confirms the power lever angle (PLA)
where is the prop brake installed?
canter shaft of the right engine prop reduction gearbox
what does the prop brake stop?
the propeller and power turbine
describe hotel mode
high pressure compressor rotor drives right AC generator and bleed air pressure is available downstream of the high pressure compressor to supply the packs
when can the prop brake be engaged?
on the ground with blue hydraulic pressure available
condition lever in feather
gust lock engaged
what must be illuminated prior to engaging the prop brake?
green ready light
how does the EEC control fuel flow to the HMU to get the desired high pressure compressor speed (NH)?
a stepper motor
what powers the EEC’s?
DC EMER BUS
BUS 1 AND 2
what 4 information inputs does the EEC recieve?
- power lever angle
- power management panel selected mode
- position of bleed air valves
- outside conditions
what are EEC inputs used for?
to calculate a new power setting before corrections are sent to the HMU stepper motor
when the EEC button is selected off, how does HMU control NH?
based on position of power lever
what does a flashing EEC fault mean?
a fault has occured at a power lever angle of more than 52 degrees. the power will be locked at the pre-fault value
what should we do if we get a flashing EEC fault?
bring power lever into the green, This causes reversion into HMU based law. EEC can be selected off.
what do we lose if we deselect the EEC?
propeller underspeed at low power
how to power levers control fuel flow above the beta range when manual fuel scheduling?
via the HMU
how do power levers control fuel flow when manually fuel scheduling below the beta range?
PVM
when does flight beta range begin?
below 62 degrees power lever angle
what is the ground beta range?
between ground idle and flight idle stops
what do the condition levers control through a valve in the HMU?
PROP FEATHERING, SPEED AND FUEL SHUTOFF
when is top law used?
when the the selected EEC is used
when is base law used?
when the EEC is inoperative or deselected and fuel flow is determined by the PLA
What will NH change with in base law mode?
ambient conditions
what will we not have in base law mode?
underspeed control
what does the underspeed control in top mode stop the NH from going below?
70.8%
what mode prevents NH overspeed protection?
top law
when is the NH backup law acivated in top law mode?
- low power settings
- hotel mode
- engine torque control failure
how does top law optimise low pressure compressor operation?
modulation of handling bleed valve
what are the 3 modes of propeller speed governing?
- blade angle governing mode
- fuel governing mode
- transition mode
what is the normal prop governing mode for flight?
blade angle governing mode
in blade angle govenring mode, how is the blade modulated?
PVM adjusts pitch as to maintain constant speed. Available regardless of EEC status
how is the engine managed in blade angle governing mode?
power management selector orders engine speed through the PEC and the Power levers command the power
when is fuel governing mode available?
when the condition lever is in the auto position
what happens in the fuel governing mode?
EEC increases fuel flow to maintain minimum propeller speed
when is fuel governing mode not available?
when feathered or the EEC is off
when is transition mode active?
on the ground
in flight at low speed/power setting
what will the prop speed be in the transition mode?
between 70.8% and 100%
what are the power levers mechanically connected to?
the PVM and HMU
How do the power levers control thrust?
through blade angle and fuel flow
what does the pvm control?
propeller pitch, which regulates propeller speed (NP)
what controls pitch change in the forward thrust range?
PVM
what will the PVM do as power levers are retarded to flight idle?
PVM reduces blade angle to maintain selected propellor RPM as long as the condition levers are in auto
when do the power levers acquire direct blade angle control?
slightly above flight idle
what happens if prop speed drops below 70.8%
EEC increases fuel flow to maintain 70.8%
what is the flight beta range?
FI and above
what is the ground beta range?
FI to max reverse
when is the flight idle gate unlocked?
as 1 landing gear shock absorber is compressed
what does the trigger on the power levers do?
allows the pilot to pull the PL from the flight idle detent into the ground range
what does the PVM do in the FI to GI range?
regulates power to provide speed governing in the FI to GI range
what regulates fuel flow and prop speed in the reverse range?
the PVM and HMU
what does each condition lever provide inputs to?
HMU and PVM of the associated engine
when in the forward thrust constant speed range what does the condition lever set?
sets prop speed through input to the governor and PVM
what engine speed is governed at the 100% overide detent on the condition lever
1200rpm
how does the condition lever control propeller speed in the auto position?
through the power management selector position
what is disabled with the condition lever in the feathered position?
propeller underspeed governing
what does the ATPCS provide for the failed engine?
automatic feathering
what 5 conditions arm the ATPCS?
- PWR Management set for takeoff
- ATPCS button armed
- both power levers greater than 49 degrees
- both toques greater than 46%
- aircraft on ground
when will automatic uptrim be disabled?
when power management is moved out of takeoff
what does the AFU supply torque indications to?
fdau
mfc
flight deck indication
what does the MFC handle during an engine failure?
- autofeather logic
- uptrim logic
- signals the effected solenoid and feathering pump
- signals the uptrims
when does uptrim occur?
2.15 seconds prior to autrofeather
what is the only power management system used to restart a failed engine?
MCT
what does the EEC interface with?
the PEC and the HMU
what is propeller speed governed at in the 100% override position?
1200rpm
how is ground idle operation permitted with the propeller feathered?
underspeed fuel governor is disabled with CL in feather
how is the prop unfetahered following an engine restart in flight?
selecting MCT on the PWR MGT panel
