ENG OVERALL Flashcards
What is the engines name / what type is it?
T700-GE-401C/D // A front-drive turboshaft engine
List the five sections of the T700-GE-401C/D engine.
- Inlet
- Compressor
- Combustor
- Turbine
- Exhaust
These sections work together to facilitate the engine’s operation.
What does HMU stand for
Hydromechanical Control Unit
What is the role of the enhanced digital electronic control unit (EDECU)
To provide advanced engine control and monitoring
What system does the T700-GE-401C/D engine use for lubrication?
A self-contained lubrication system
What component in the eng is responsible for boosting fuel pressure?
Engine-driven fuel boost pump
The HMU is responsible for controlling what? ( Think big picture))
The HMU is responsible for controlling fuel flow and engine performance.
How is the inlet cowling heated to prevent ice formation?
Using fifth stage bleed air via the inlet anti-ice valve
This heating mechanism is crucial for maintaining airflow and engine performance in cold conditions.
What feature of the inlet fairing allows for anti-icing?
Perforated with small slits
These slits enable fifth stage bleed air to heat the exposed inlet surface.
What is the function of the swirl vanes in the inlet section?
To impart rotation to the airflow
This rotation is essential for effective airflow management and particle separation.
What does the Inlet Particle Separator (IPS) do? Keep this one get rid of the other one
Prevents foreign particles from entering the compressor
The IPS uses centrifugal force to eject particles into a collection scroll.
What happens to the discharge airflow from the IPS?
It passes over the scroll vanes and is then dumped overboard through the blower assembly
What is the role of the deswirl vanes in the inlet section?
To remove the rotation, This provides smooth airflow to the compressor.
What does the compressor section consist of?
A five-stage axial and a single-stage centrifugal rotor/stator assembly
These components work together to compress the incoming air for combustion.
What are the key components of the combustion section?
Flow-through annular combustion chamber, two igniters, 12 fuel injectors
These components are essential for the combustion process in the engine.
What are the four functions of the Overspeed and Drain Valve (ODV)? (H: PRTP)
- Provides main fuel flow to the 12 fuel injectors during engine start and operation.
2.) Returns fuel back to the HMU if the Np overspeed is energized or if the EDECU hot start preventer is activated
3.)Traps fuel upstream, which keeps the fuel/oil heat exchanger full, so that system priming is not required prior to the next start.
4.)Purges the main fuel manifold overboard, after engine shutdown, through a shutoff and drain valve to prevent coking of the fuel injectors.
What drives the compressor and Accessory Gearbox (AGB)
The Ng turbine drives the compressor and Accessory Gearbox (AGB)
The N g turbine is a two-stage, air-cooled, high-performance axial design.
What percentage of the total airflow through the engine is used for combustion?
Approximately 30 percent of the total airflow is used for the combustion process.
List the uses of the remaining airflow in the engine.
- Compressor inlet temperature (T2) air
- Compressor discharge pressure (P3) air
- Combustor and turbine cooling
- Engine oil seal pressurization
What components are driven by the rear face of the AGB? ( H: Car Store)
- Engine starter
- HMU
- IPS blower
- Overspeed and Drain Valve (ODV)
Who are the major players for the Eng control System ( 4 Player)
- HMU
- ODV
- EDECU
- Engine-driven alternator
How does the HMU interact with the EDECU in the Engine Control System?
The HMU controls the gas generator while the EDECU trims HMU to satisfy the load requirements
What happens when the PCL is in the OFF position?
The Power Available Spindle (PAS) mechanically shuts off fuel at the shutoff valve within the HMU.
What does moving the PCL to the IDLE position accomplish?
It allows the HMU to automatically control start sequence fuel flow for self-sustaining combustion.
What is the function of the Load Demand System? I like this one better than the other one.
The Load Demand System automatically controls engine speed and provides required power based on collective position.
Fill in the blank: The _______ is designed to minimize vulnerability and fire hazard in the event of damaged fuel lines.
engine-driven fuel boost pump
How many stages does NG have
The N g turbine is a two-stage, air-cooled, high-performance axial design.
Where does fuel come from before entering the fuel filter?
From the engine-driven fuel boost pump
What happens when a pressure differential across the fuel filter is sensed?
The impending bypass Pressure Differential Indicator (PDI) extends
Can the impending bypass PDI be reset without maintenance?
No, it cannot be reset until the filter element is removed
What caution appears once the filter is bypassed? Referring to Fuel
1/#2 FUEL FLTR BYPASS caution
What is the role of the metering valve in the HMU?
To ensure proper fuel flow to the engine
What does the HMU respond to in terms of cockpit inputs?
2 Mech and 1 Elec
- First mechanical input from the LDS
- Second mechanical input from the PCL
- Electrical signal from the EDECU
What are the functions of the HMU in response to the PCL?
- Fuel shutoff
- Setting engine start fuel flow
- Setting permissible N g up to maximum
- Fuel priming
- EDECU override capability (LOCKOUT)
What inputs does the HMU respond to that influence fuel flow?
- T2
- P3
- N g
What is the function of the HMU when there is no input to the torque motor from the EDECU?
Operates as a conventional gas-generator power control
What feedback mechanism does the HMU use to tell the EDCU it can stop trimming down power?
Provides a feedback signal to the EDECU via the LVDT
What happens to excess fuel in the HMU?
Routed back to the pump inlet
At what point does the N g overspeed valve trip?
At 110 ±2 percent N g
What is the purpose of having the actual level of engine power in FLY set higher than required?
To ensure fail-safe to high power and available power with One Engine Inoperative (OEI)
What are the functions provided by the HMU?
Rapid engine transient response, automatic fuel scheduling for engine start, Ng overspeed protection, N g governing, acceleration limiting, flameout and compressor stall protection
What is the primary function of the alternator in the engine?
Powers all essential engine electrical functions
What inputs does the EDECU receive from the cockpit?
- ENG SPD TRIM switch
- CONTGCY PWR switch
- ENG OVERSPEED TEST A and B buttons
What signals does the EDECU send to the cockpit? (Look UP)
- Torque
- Np
- TGT
- Contingency power
At what Np percentage does the overspeed system get actuated?
120% Np
Exceeding this limit triggers a signal to divert fuel, causing engine flameout.
True or False: Resetting a popped NO. 1 or NO. 2 ENG OVSP circuit breaker in flight is safe.
False
It may initiate an engine overspeed signal and result in engine failure.
What is the purpose of TGT limiting in the EDECU?
To limit fuel flow when measured TGT exceeds a fixed reference TGT
The reference TGT is also known as the MRP limiter setting.
How does the engine load sharing function in the EDECU?
Compares torque signals between two engines and generates a torque error signal
The EDECU increases power on the lower torque engine.
What does the ENG SPD TRIM switch do?
Controls Np of both engines simultaneously
It does not provide individual engine trim capability.
Fill in the blank: The CONTGCY PWR switch allows TGT to increase above the _______.
MRP limiter setting
What triggers the auto-contingency power feature?
When torque from one engine is below 50%
The opposite engine’s EDECU will reset the TGT limiter.
What conditions must exist for dual-engine auto-contingency power to activate?
- TGT within 11 °C of MRP limiter setting
- N p drops below 96%
- Greater than 3% droop between actual N p and reference set point
- Greater than 5% per second N p droop rate
What does the Np overspeed test involve?
This lowers the N p overspeed limit from 120% to 96%.
What happens when the EDECU is in LOCKOUT mode?
Manual control of Ng and Np is enabled
Engine power is no longer controlled by the EDECU.
What does the hot start prevention feature detect?
A hot start when TGT exceeds 900 °C with low Ng and Np
It stops fuel flow and restores it when TGT decreases.
What is the purpose of the transient droop improvement (TDI) system?
Initiates power turbine acceleration early
It uses anticipator signals to increase fuel flow at low torque settings.
What does the auto-ignition system do during an Np overspeed condition?
Automatically initiates ignition sequence for 5 seconds
It cycles until the N p overspeed condition is controlled.
What is the Ng decay rate relight feature / at what % Ng does it deactivate it`s self?
Turns on igniters for 5 seconds to relight the engine if it flames out
This feature is disabled below 62% N g.
What does the fault diagnostic system in the EDECU do?
Identifies failed components or circuits with fault codes
Codes are displayed on the engine torque indicator with descriptions.
What three things does the Alternator provide AC power to
Ignitor assembly, EDECU, and Ng signal to the vertical instruments.
What is the purpose of the thermal lockout in the impending bypass below what temperatures?
It prevents the indicator from popping during cold-weather starting below 38 °C.
This feature ensures accurate readings during low-temperature conditions.
How does the oil cooler function/ Where does it flow too after the Oil Cooler?
It transfers heat from the oil to fuel, cooling the oil as it passes through.
After the oil cooler, it flows through scroll vanes that also cool the oil.
What are the three pneumatic sources for engine starts?
- Auxiliary Power Unit (APU)
- Engine crossbleed air
- External pneumatic power
What does the AIR SOURCE ECS/START switch do?
It selects the source of air pressure for engine start and ECS operation.
What happens when the starter button is pressed?
Air from the selected source is directed through the start valve to the engine starter.
What is the minimum N g for the receiving engine in a crossbleed start?
24 percent N g.
This requires the donor engine to have an N g of approximately 90 to 94 percent.
Fill in the blank: The #1/#2 ENG ANTI-ICE ON advisory will remain until the _______ is closed.
anti-ice/start bleed valve
What does the engine anti-ice/start bleed valve provide when anti-ice is selected ON?
Fifth stage bleed air
The valve automatically opens during engine starts.
At what Ng percentage does the anti-ice/start bleed valve remain open during engine starts / why does it remain open?
Below 80.5% N g
This is to prevent compressor instability during starts.
Anti-Ice/start bleed value should be closed above what % Ng / what are the two reasons why it might not be closed ?
96.5 % Ng / It closes unless anti-ice is selected ON or electrical power is lost
The range of acceptable Ng speeds at which the valve operates is dependent on OAT.
What (3) thing indicate a malfunctioning anti-ice/start bleed valve?
Any of the following:
* Appearance/disappearance of ENG ANTI-ICE ON advisory outside specified range
* No appearance of ENG ANTI-ICE ON advisory when switch is ON
* No rise in TGT when switch is ON
With ENG ANTI-ICE ON, maximum torque available is reduced up to 18% per engine.
What temperature does the inlet thermal switch activate the INLET ANTI-ICE ON advisory?
Approximately 93 °C
Full inlet anti-ice capability may not be available above 4 °C.
What happens with the NO. 1 and NO. 2 ENG ANTI-ICE switches OFF?
The solenoid is energized and the valve is closed
When the switches are ON, the valve is variably open based on OAT.
What controls the engine inlet anti-ice valve when the switches are OFF and ice is detected?
The valve is variably open based on OAT
This occurs with the DE-ICE MASTER switch ON.
How does the Freon-filled bellows operate in relation to the inlet anti-ice valve?
It reacts to ambient temperature and controls the valve
What indicates a malfunctioning engine inlet anti-ice valve?
Appearance of the INLET ANTI-ICE ON advisory when OAT is greater than 13 °C
The resultant loss of torque could be a maximum of 49% when the anti-ice valves are open.
Based off the Freon-Filled Bellows when is the Value open/ value begins to close/ and is completly closed ?
Less than 4 °C: valve open; 4 to 13 °C: valve closes; above 13 °C: valve closed.
What are the 16 Functions of the EDCU?
1.) Ng Govering
2.) Eng speed trim.
3.)Np Overspeed Test.
4.) Np overspend Protection
5.) Auto Ignation
6.) Ng Decay rate relight feature
7.) Load Sharing
8.) TGT Limiting
9) Manual C-Power
10) Auto- C Pwr
11) Dual Engine Auto
12) Transient droop improvement
13.) Cockpit Signals
14.) EDECU Lockout
15.) Hot Start Prevention
16.) Fault Diagnostic
The EDECU receives the following input signals from the helicopter (4)
What the EDECU needs to do it’s job
- Torque from the other EDECU.
- N p demand.
- 400-Hz backup power.
- HMU (LVDT).
The EDECU receives the following inputs from the cockpit: (H: How can I influence the EDECU on the ground?)
- ENG SPD TRIM switch.
- CONTGCY PWR switch.
- ENG OVERSPEED TEST A and B buttons.
What is the MRP Limit?
866+/-10
What is the CRP
891+/- 10
