Powerplant Flashcards
What engines does 120 have
PW118, A, B
What is the difference in the engines
A and B have better performance
What kind of props does the 120 have
Hamilton Sundstrand 14rf-9
4 blades 10.5 ft diameter
How many compressors does each engine have
2 centrifugal compressors
What is TMM and what is run my TMM
Turbo machinery module
1. Starter/generator
2. HMU
3. Oil pump
4. Fuel pump
What is HMU
Hydrotechnical Metering Unit. The mechanical fuel, it takes inputs from different systems and creates fuel schedule
What is RGB and what is run by RGB
Auxiliary Gen
Hydraulic pump
Axillary Feater pump
What is RGB and what is run by RGB
Auxiliary Gen
Hydraulic pump
Axillary Feather pump
PCU oil pump
Overspeed governor
PCU
What is PCU
Propeller Control Unit
Primary governor
Controls prop pitch and speed
Are the compressors and power turbine connected
No the compressor section creates enough airflow to the combustion section to sustain continuous combustion. The turbine section converts energy form the expanding gasses exiting the combustion chamber in to rotational force used to drive the compressor, propeller, and accessories
Do turbines spin in different direction
Yes to prevent torque effect
How much HP is the engine rated for
18000 SHP
Roughly how much air is used for cooling and combustion
About 75% for cooling and 25% for combustion
What kind of oil system does the engine have
Pressure system
How much oil can the system hold
2.4 Gal
Is the oil pressure gage and the oil light connected
No
How many fuel nozzles does each engine have
14 that produce continuous flow of fuel
How many igniter does the aircraft have
2
What is a Hot start
When either too much fuel or not enough air. T6 raises very rapidly
What is a Hung start
A hung start is a start that begins but doesn’t finish properly
What is EEC
Electronic Engine Control - takes fuel information form the HMU and other engine inputs and fine tunes the HMU fuel scheduling
Functions of EEC
- Idle speed governing
- Np fuel governing
- Acceleration/Deceleration control
- Fixed torque climb
- HMU de-enrichment
What happens at 14,000 ft
When climbing through 14,000 ft the fuel gets too rich for EEC so HMU de-enriches the fuel schedule so the EEC can properly utilize the fuel schedule. When descending back trough 14,000 ft the HMU will re-enrich the fuel schedule. If re-enrichment doesn’t happen you will get a tipple chime and “ENGINE CONTROL”
What is the ax RPM for the Propeller
1300 RPM
How much oil is in the AUX tank
0.3 gallons enough to go to full forward to full feather once. If the engine is spinning it will re-fill itself
Explain how the propeller works
The PCU is commanded by Power lever and Condition levers. When a pitch change is commanded, the PCU changes the rotational speed of the transfer tube (normally rotates the same speed as the prop) either faster or slower than the prop speed. This speed change is obtained by 2 distinct oil pressures; supply and control. The supply pressure actuates to increase pitch and control pressure actuates to decrease pitch. When the transfer tube speed is increased or decreased it opens 1 or 2 chambers. When oil enters either chamber it move the actuator piston witch then changes the pitch of the blades
What condition must be met for auto feather to work
Switch to on
PLA grater than 62°
Tq of both engines must be above 62%
Why prop sync have to be off during takeoff
Because the left engine is the Master and the right engine is slaved to the left, so if the left engine would have failed the right engine would try to match the Np of left engine
How close the props have to be for prop sync to work
2.5%
How any turbines does the engine have. How many power turbines
4 turbines total, 2 power turbines
What should be Ground and Flight idle Nh with EEC ON
Ground 62%
Flight 72%
What happens if EEC fail below 14,000 ft
They fail fixes at whatever schedule they are in
What is the flight idle stop and how does it work
Prevents the power levers from going into reverse while in flight. A weight on wheels switch removes the block on the ground
When is prop heat available
Oil pressure 40 psi
What ways can the prop be feathered
Manually
Electrically
Auto feather
Fire T handle
What is the low pitch secondary stop
If primary pitch stop fail the props will keep propeller at around 12.6° thus prevents then form going into reverse
What could be a reason for beta light in flight
Surging prop
What keeps the prop at selected speed
Primary speed governor, uses flyweights
Explain how the overspeed governor takes over
The least selector valve chooses the lowest pressure between the primary governor and overspeed governor. The primary governor has lower pressure then the overspeed governor in normal operations. If the normal speed governor fail, the pressure will increase making the overspeed governor oil pressure the lower of the two. The least selector valve will then choose the overspeed governor
What Nh will the overspeed governor try to keep the prop in
103%
What if overspeed governor cant maintain 103% Nh
Fuel topping governor will reduce amount of fuel to the combustion chamber keeping Nh at 107%
What happens if the prop system looses oil pressure
Fixed pitch prop. Prop is driven toward flat pitch until it closes pitch lock gap which keeps the prop fixed
Engine power control is accomplished by operation of
A combination of the EEC and HMU
The device that provides essential fuel control in the absence of electrical power
HMU
The EEC normally is used in what position
TO or ON
If EEC light on the glareshield illuminates, this indicates
An electrical failure exists in the system
Minimum oil temperature for takeoff
45°
Oil pressure alarm light will illuminate at
40 PSID
The PW118 combustion section is defined as
Reverse flow annular combustion
Power lever provides direct control to
HMU
During engine start with ignition system set to AUTO
The ignitors come on automatically
The ignitors go off automatically
What indication does the pilot have to indicate the engine ignitors are energized
A white ignition light
After initiation a start cycle automatically interrupted at approximately
50% Nh
Engine oil is also used for
Fuel heating
Fuel flow to the engine is metered by
HMU/EEC
The EEC has a function called
Failed fixed
EEC control functions are activated at
25% Nh
In normal operation, maximum governed propeller speed is
1290-1309 RPM
Normal operation range for a propeller
79.2°(feather) to -15°(reverse)
In flight Np is controlled by
PCU
The main component for changing propeller pitch
Propeller servomechanism
During taxi and reverse witch unit controls Np
PCU
Which control input sets the speed for a prop governor
Condition levers
When in BETA range
The speed governor no control of propeller pitch
Beta valve position is adjusted by
Power levers
Will the propeller feather atomically in flight if it has not fathered after an engine failure
No
Propeller sync is activated by
System on and Np > 80%
