Engines and Props Flashcards
What type of engines does the Braz have
PW 118 A
What is the rated power output of engine
1800 SHP
How many compressors does the engine have
2 Centrifugal compressors
How many turbines does the engine have
3
2 x Single stage axial turbines
1 x 2 stage axial turbine
At what point will the starter generator switch over to being generator
50% Nh
As well as lubrication what is an additional use of the oil
Heat the fuel
Each engine has how many compressor bleed ports
2 x Low Px, Station 2.5, 12 o’clock / 2 o’clock
1 x High Px, Station 3, 10 o’clock
On approach with auto-feather armed, if the engine fails will it feather
No, conditions not meet
PLA (PWR LVR ANG) greater than 62
Tq greater than 62%
What type of combustion chamber
Reverse Flow annular, 14 nozzles
Engine power control is maintained by
Electronic Engine Control (EEC) and the Hydromechanical Control unit (HMU)
What controls the fuel flow in the absence of electrical power, EEC failure
Hydromechanical Control unit (HMU)
The EEC (Electric Engine Control) is powered by
Emergency DC Buses
and b/up emergency Dc buses
The EEC normally what position
TO - AUTO
What does the Illumination of the glare shield EEC light indicate
Respective EEC failure detected
Oil Pressure Light activates at?
a. Limitations (note 11)
40 psid light
40 mins with oil between 40 - 55 only if NH below 75%
(i.e. flt idle)
Condition Lever job is to?
Positions and guards
Min FLT , Taxi
RPM
Mechanically connected to PCU, also HMU for shutdown
Fuel Shut OFF / Feather Min RPM / Max RPM
80% Np Min FLt
50% NP Taxi
Power Lever function is to?
Positions and guards
Provides direct control over
FLT Ops NH
Mechanically connected to HMU ( Power lever angle (PLA) controls fuel schedule) and electrically to EEC
PCU (for ground Ops in Beta range), controls pitch for fixed Np - taxi(50%Np) and reverse(80.5%Np EEC controlled)
*Controls Low pitch lock schedule PCU
Ignition system
Auto
On
Off
Auto - will activate during start sequence and auto disconnect at 50% Nh changing from starter to generator
On - Ignition circuit is continuously energized
Off - De-energized - used for DRY motoring
Clearing fuel after WET start
Lowering T6 after HOT start
Fuel flow to the engine is metered by
HMU / EEC
EEC has a Fail____ Function
a. This does what
Fixed - sensor fail only, not full EEC fail
Freezes Torque motor to prevent spool backs during T/Off, fix prop pitch
-Active below FL140-
What is the role of the 14K and 10 K switches
14 K changes fuel schedule for the HMU passing FL140,
Leans climbing through and enrichens on descent,allows EEC to adjust fuel schedule
If 14K fails passing 10K this switch throws a fault warning
EEC control functions activates at
25% Nh
What props does the Braz have
Hamilton Sundstrand 14 RF-9 Commuter Propeller
Constant Speed, reversible, Full Feathering
Prop tip clearance
18”
Normal ops Props max governed speed
1300 RPM (range 1300 - 1313)
Pitch range
-15.0 through to +79.2 - measured at 42”
What controls Np?
During ground Ops?
In Flt?
In Flight PCU
On the Ground fixed Power lever via the BETA valve
MIN RPM 50% Np / MAX RPM 65%Np
What sort of screw is used in governor
acme reverse thread screw, changes actuators position to allow oils to flow from different chambers
What is pitch lock?
How is it achieved
Pitch lock gap
Change of 1% or 2Np closed the gap trapping oil and stopping further reductions in prop pitch
What do the BETA lights on glareshield indicate?
In flight
On the ground?
In flight FLASHING - primary low pitch stop has failed secondary low pitch stop is working
Normal on GRD
What is the BETA valve?
What does it do?
In flight controls Low Pitch Back Stop, controls speed governor not allowing prop pitch below established values
Power lever below FLT Idle
Control blade angle for ground Ops, activated when
Commanded directly by Power lever
What if the function of the Least select valve
Hydraulic Discriminator between Governor section and Over speed governor
Prop sync is activated by
Switch
Only Operates between 80% - 100& Np
Left prop is master
won’t activate if Np diff greater than 2.5%
PCU Oil Pressures
Aux Oil tank feed approx 100 psi
Propeller Oil Pump boosts to 780 psi
Aux Pump Px 820 psi for feathering
Reverse Valve
Controlled by Power lever selects either governor or Beta valve to control prop pitch
FLT Idle up - Governor
Grd Ops - BETA Valve
How many Spools does PW118a have
3
Low Press
High Press
Power Spool
Which spool drives the starter generator start sequence
High Press spool
What is the purpose of the S Shaped duct in the air induction inlet
Inertial separator, removes FOD by bending the airflow
How many fuel injector nozzles are there in the combustion chamber
14
Where is the T6 temp measured
Between the 2nd stage turbine and the power turbine
HP Spool and Power Spool
How much does the RGB reduce the RPM going to the prop shaft
15:1 reduction through 2 stage gearbox, reduces RPM and increases the torque
Is the HMU driven by the TMM gearbox (HP spool)
No located on it through the fuel pump,
Fuel pump driven by gearbox but HMU not driven by it
How is the AUX oil tank (EFP),( electric feather pump reservoir) replenished
Automatically filled by oil system when engine is running or being dry motored
Dry motoring, turning starter without adding fuel to spin the engine
What safe guards does prop heat have on the ground
Will only function when oil press is above 40 psid
Engine low oil pressure switch
What does the abort selection on starter switch do
Aborts the start by sending an artificial NH 50% to the GCU - this ends the start cycle
Is a generator alone sufficient to an engine
No, requires assistance from the main battery
At what point does pilot introduce fuel during the start sequence
Passing NH 10% condition lever moved from Cut Off to Feather
-make sure temp below 200, hot start delay fuel input-Prior to 19%
What is the time limits for “light Up” during engine start?
10 secs for light Off (T6 begins to rise)
Nh Governing Speeds
EEC maintains Ground Idle Nh 62%
Flight idle Nh 72%
EEC safety features
Nh Overspeed
Nh undespeed
Nh under 60% EEC switches OFF
Nh over 103% EEC switches OFF
EEC failure, signs and actions
EEC lights on GLARESHIELD
System reverts to HMU, resulting in power loss
Add 20% Torque
