NATOPS Chapter 2 Flashcards
Aircraft Engines
four AE 2100D3 turboprop engines
Takeoff Power (Maximum)
4,700 hp at temperatures up to 39.4 degrees C, at sea level with no bleed air
Maximum Continuous Power
4,700 hp at temperatures up to 28.3 degrees C, at sea level with both air conditioners on
Three major assemblies of the engine
1) Power section (two-rotor system with a free power turbine)
2) Propeller gearbox (plus propeller)
3) Joined by a torquemeter (shaft and interconnecting struts)
Propeller Gearbox function
Transmit power from the torquemeter to the propeller, reduce shaft RPM, and provide shaft power to the GMAD
GMAD what is it and what does it do?
Gear mounted accessory drive.
Located on the PGB, provides drive pads for the aircraft hydraulic pump, an oil cooled ac generator, the PGB oil supply and scavenge pump, propeller high pressure oil pump and overspeed governor, and the propeller pitch control unit.
Torquemeter function
Transmit engine output power to the PGB and to supply torque reference to the FADEC’s
Power section primary features
1) Fourteen-stage axial flow, variable speed compressor. The inlet guide vane and the first five stator stages are variable.
2) Two-stage air-cooled, variable speed gas generator turbine; two-stage free power turbine.
3) Two FADECs for redundant, fully integrated control of engine and propeller system
Power section accessory gearbox contains
1) Gearbox-driven FPMU
2) PMA
3) Oil pressure and scavenge pumps
4) Air turbine starter
What is a FADEC and what does it do?
Full Authority Digital Electronic Control
2-identical single channel FADECs (A and B). Control propeller and engine. Provide data, status info, and fault indications to the mission computer. During engine operation both are functional, however only one is in actual control.
What determines the controlling FADEC?
1) Each time an engine start is initiated with weight on wheels, the FADEC selection automatically alternates.
2) FADEC fault serious enough to render the controlling
Input parameters used by the FADECs for controlling the engine and propeller include:
1) Torquemeter (HP)
2) Gas generator speed (NG)
3) Power turbine speed (NP)
4) Measured gas temperature (MGT)
5) Compressor inlet air temperature and pressure
6) Fuel metering valve position
7) Compressor variable guide vane position
8) Prop blade angle
9) Prop magnetic pulse unit
10) Nacelle ambient air pressure
When engine speed reaches approximately ___ percent, the engine ___ supplies electrical power for the FADEC operation.
40%
PMA
Explain prop speed (NP)
Accomplished by varying propeller blade angle and/or engine fuel flow. The blade angle is controlled by the PCU in response to the FADEC. The FADEC controls engine fuel flow by providing signals to the FPMU
Forward Thrust is…
When the power levers are forward of FLT IDLE, FADEC schedules torque as a function of power lever angle. The prop speed is maintained at 100 percent through blade angle changes.
Ground Range is…
When the power levers are between FLT IDLE and reverse range, the FADEC schedules blade angle as a function of power lever angle. The propeller speed is maintained at 99 percent through fuel flow changes.
Reverse Thrust is…
When the power levers are in the reverse range, the FADEC schedules torque as a function of power lever angle. The prop speed is maintained at 101 percent through blade angle changes.
GND IDLE Blade Angle vs. Calibrated Airspeed
When the power levers are at GND IDLE, the FADEC programs the inboard and outboard propeller blade angles differently as a function of calibrated airspeed.
Outboard blade angle above 110 knots
Outboard props 1 degree blade angle
Outboard blade angle between 110 and 90 knots…
Outboard props increase from 1 degree to 8 degrees blade angle
Blade angle between 70 and 50 knots…
Outboard decrease from 8 degrees back to 1 degree. T
Inboard props are set to 1 degree.
Blade angle below 50 kts…
All props are at 1 degree
Inboard props blade angle at all calibrated airspeeds down to 70 knots…
-2 degrees
FADEC autofeather request parameters:
The FADEC will request MC permission to autofeather if the power lever is at ___ ____ or above and any of the following exist:
a. Loss of prop control (high power and NP below 73 percent)
b. At low power settings, low NG (less than 69 percent)
c. At high power settings, low engine HP (less than 74 percent of commanded HP) and decelerating NG (greather than 500 rpm per second)
MC autofeather permission…
The outboard props always have MC permission to autofeather without delay (low min control speeds).
Inboard props auto-fx permission is granted after a 2 second delay provided the a/c is below 15,500 feet and the engines are running normally. If NOT, the FADEC will windmill the prop at 100 percent. If all engines flameout atleast one inboard will windmill to supply electric and hydraulic power.
If a flameout is detected, the FADEC initiates ignition and monitors for a relight. IF relight does not occur before NG decreases below __ percent, the FADEC auto shuts off fuel to shut down the engine.
56
FADEC shuts down the engine start sequence for:
No light-off
Flameout
RPM stagnation
Manual feathering will only work when:
Only functions if the START switch is in STOP or if the power levers are at GND IDLE and low-speed ground idle is selected.
What happens when you place the PROP Control switch to feather:
The auxiliary feather pump is turned on and automatically shuts off after 20 seconds.
If NP exceeds _____ percent, the _____ _____ ____ diverts pump oil away from the PCU to allow the blade counterweights to increase blade angle and control the overspeed.
104.5 percent
propeller overspeed governor
If NP exceeds ___ percent, the FADEC reduces ____ ____.
106 percent
fuel flow
If NG exceeds ___ percent or NP exceeds ___ percent the FADEC auto shuts down the engine.
109 percent
119 percent
The ATCS schedules from __ to ___ percent of takeoff power over a __ knot range.
50 to 100 percent
40 knot
How do you override ATCS on the ground?
Pushing the autothrottle disconnect buttons on No. 1 or No. 4 power levers.
How do you override ATCS in the air?
If the WOW and ATCS is displayed, press the autothrottle disconnect button 3 times within 2 seconds to override.
What is the NIU and where is it mounted?
The Nacelle Interface Unit is mounted near the FADEC units in the Nacelle above the engine.
What does the NIU do?
1) Provides MIL-STD-1553 and RS422 comms
2) Indications of oil temp, pressure and quantity, oil cooler flap position and fuel flow
3) Controls oil cooler flap and engine/nacelle anti-ice valves.
4) Engine health and usage monitoring through the EMS.
Where is the oil tank and what are the specs?
A 20-gallon tank in each nacelle above the engine.
12-gallon oil capacity with the remaining 8 gallons for air space.
0.66-gallon dedicated reservoir for the emergency feather pump oil supply.
What does the oil system do?
Independent oil systems, one for each engine, lubricate the engine power section and GMAD/PGB.
The oil cooler augmentation system supplements normal oil cooling during extended ground operation by using __th stage bleed air when the power levers are below FLT IDLE.
14th stage
Oil cooler augmentation is operating when:
1) oil cooler flap position greater than 80%
2) oil temperature above approx 80 degrees C
3) airspeed less than 50 knots
4) Power levers are less than FLD IDLE
5) WOW switch
What happens when you place the engine start switch to STOP?
Shuts off fuel at the engine, turns off respective main tank boost pump, closes the nacelle shutoff valve. During the auto start cycle, it also closes the starter regulating and shutoff valve and deenergizes the ignition.
What happens when you place the engine start switch to MOTOR?
Motors the engine to remove unburned fuel in case of no ignition, or to cool the engine following an aborted start attempt. Opens the nacelle shutoff valve and starter regulating and shutoff valve.