EMB120 Power Plant Systems Flashcards
What Engines does the 120 have?
P&W 118
P&W 118(a)
P&W 118(b)
What is the difference in the engines?
The (a) and (b) engines have better internals that allow the engine to stay cooler longer
What kind of Prop does it have?
Hamilton Sunstrane 14RF-9
4 Blades
How many compressors does each engine have?
2 compressors
What is the TMM?
Turbo Machinery Module
What is all run/powered on the TMM?
Starter/Generator
HMU
Fuel Pump
Oil Pump
What is the HMU?
Hydro Mechanical Metering Unit
The Mechanical Fuel controller, it take engine inputs, pressures and settings and creates a “fuel schedule”
gives a range of fuel to the engine
the carburetor or fuel injection system
What is the RGB?
Reduction Gear Box
What is run/powered by the RGB?
Auxiliary Feather Pump Hydraulic Pump Auxiliary Generator PCU Oil Pump Over Speed Governor PCU
What is the PCU?
Propeller Control Unit
Primary governor
Controls prop speed and pitch
Are the Compressors and the power turbine connected
No, the compressor section creates enough airflow to the combustion section to sustain continuous combustion. The turbine section converts energy from the expanding gasses exiting the combustion chamber into rotational force used to drive the compressors, propeller, and accessories.
Do the turbines spin different directions?
yes to help prevent torque effect
How much horse power is the engine rated for?
1800 SHP
Roughly how much air used for cooling and for the fire in the engine?
25% to burn
75% to cool
What kind of oil system does the engine have?
Pressure system
How much oil can the system hold?
2.4 Gallons
Is the oil pressure gage and the oil light connected?
No
How many fuel nozzles does each engine have?
14 that produce a continuous flow of fuel
How many igniters does the aircraft have?
2 and they are only on during start
What is a Hot Start?
When there is either too much fuel or not enough air the T6 temp rises very rapidly
What is a Hung Start?
A hung start is a start that begins but doesn’t finish properly and gets stuck
What is the EEC?
Electronic Engine Control
takes info from the HMU and other engine inputs and fine tunes the HMU fuel schedule
protected against Compressor stalls
Fixed torque Climb - Sets the power and it attempts to hold the same torque during climb
What happens at 14,000ft?
when climbing through 14,000ft The fuel gets too rich for the EEC so the HMU de-enriched the fuel schedule so the EEC can properly utilize the fuel schedule. when descending back through 14,000 the HMU will re-enrich the fuel schedule. If the re-enrichment doesn’t happen by 10,000ft you will get a triple chime and “ENGINE CONTROL”
what is the max RPM of the Propeller?
1300RPM
How much oil is the AUX oil tank?
0.3 gallons enough oil to go from full forward to full feather once. If the Engine is still spinning it will refill itself
Explain how the prop system works.
The PCU is commanded by the power levers and the condition levers. When a pitch change is commanded, the PCU changes the rotational speed of the transfer tube (normally rotates at the same speed as the prop) either faster or slower then 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 decreases it opens 1 of 2 chambers. When oil enters either chamber it moves actuator piston which then changes the pitch of the blade
What conditions must be met for auto feather to work properly?
Switch to on
PLA greater then 62 degrees
Tq of both engines must be above 62%
Why does 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 were to auto feather on takeoff then the right engine would also auto feather because it slaved to the left engine
How close do the props have to be for prop sync to work?
2.5%
How many turbine does the engines have? How many are power turbines?
4 turbines, 2 power turbines
What should be Ground idle Nh with EEC on? Flight idle?
Ground 62%
Flight 72%
What all does the EEC do?
Np fuel gov (reverse)
Smooth fuel Governing to prevent compressor stalls
Fixed torque climb
What happens if EEC fail below 14000k ft?
They fail fixed at whatever schedule they are in
What is the flight idle stop? How does it work?
Prevent the power levers from going into reverse while in flight. A weight on wheel switch removes the block when on the ground
When is prop heat available?
Oil pressure 40psi
What ways can the prop be feather?
Mechanically- condition lever
Electronically- electric feather switch
Auto feather
Low pitch secondary stop
What is the low pitch secondary back stop?
While in flight if props are in the reverse range, it sends the props back towards feather using the electronic feather solenoid. It won’t completely send the prop into feather
What could be a reason for a beta light in flight?
Surging prop
What keeps the prop and the selected speed?
Normal speed gov, uses a fly weight
Explain the how the overspeed gov takes over?
The least selector valve chooses the lowest oil pressure between the normal speed gov and the overspeed gov. The normal speed gov has lower oil pressure then the overspeed gov in normal ops. If the normal speed gov fails, the pressure will increase making the overspeed gov oil pressure the lower of the 2. The least selector valve will then choose the overspeed gov.
What Nh will the overspeed gov try to always maintain with oil pressure?
103%
What Nh will the overspeed gov try and maintain if it can’t maintain 103%?
107%, it will pull fuel from the engine to try and maintain 107%
What happens if the prop system looses oil pressure?
Fixed pitch prop
