First 20 pages of Chpt 2 Flashcards
Aircraft electrical power for the FADEC operation is required only during the initial engine starting phase. When engine speed reaches approximately __ percent, the engine PMA supplies electrical power for the FADEC operation.
40
Overspeed protection is provided for what?
propeller, power turbine, and gas generator
Significant oil pooling in the engine can cause damage, and if the engine is restarted, may result is an ___.
engine fire
What is the only required pilot control input for the FADECs?
power lever position
FADEC Auto Ignition and Automatic Engine Shutdown — If a propeller is autofeathered, the affected engine FADEC initially attempts to maintain gas generator core speed at __ rpm. If a flameout is detected, the FADEC initiates ignition and monitors for a relight. If a relight does not occur before NG decreases below __ percent, the FADEC automatically shuts off fuel to shut down the engine.
idle
56
The starting system consists of an ___ and a ___ and ___.
air turbine starter
starter regulating and shutoff valve
Primary function of the torquemeter
transmit engine output power to the PGB and to supply torque reference to the FADECs.
When is the controlling FADEC determined? (3 ways)
- Each time an engine start is initiated with weight on wheels, the FADEC selection automatically alternates.
- A FADEC fault serious enough to render the controlling FADEC incapable of safe engine operation automatically shifts control to the alternate FADEC.
- ALT selection on the FADEC control panel.
Input parameters used by the FADECs for controlling the engine and prop include:
- Torquemeter (HP).
- Gas generator speed (NG).
- Power turbine speed (NP).
- Measured gas temperature (MGT).
- Compressor inlet air temperature and pressure. 6. Fuel metering valve position.
- Compressor variable guide vane position.
- Propeller blade angle.
- Propeller magnetic pulse unit.
- Nacelle ambient air pressure.
Where is the GMAD located?
on the rear of the PGB
The engine has the following unique features: (3 things)
two full authority digital electronic controls (FADEC)
gearbox-mounted accessory drive (GMAD)
nacelle interface unit. (NIU)
Describe the starting system
On the ground, air for starting is supplied by the APU, an external air cart, or by an operating engine. The air is routed through the bleed air system and the nacelle shutoff valves. When the respective nacelle shutoff valve is opened, air is supplied to the starter regulating and shutoff valve. When the ENGINE START switch is placed to the START position the controlling FADEC initiates the engine starting sequence. The starter regulating and shutoff valve regulates airflow to the starter in response to a signal from the controlling FADEC.
Do not use the ATCS override function unless ___. If ATCS override is used, manual reduction of power may be required to maintain directional control.
an outboard engine has failed, the ATCS DEGRADED caution is displayed and climb performance is inadequate to clear an obstacle
If NP exceeds __ percent, the propeller overspeed governor diverts pump oil away from the __ to allow the blade counterweights to increase blade angle and control the overspeed. If NP exceeds __ percent, the FADEC reduces fuel flow.
104.5
PCU
106
The aircraft is powered by four ___ turboprop engines
AE 2100D3
Engine starts with excessive oil in the ___ will severely damage the gearbox and engine. Maintenance is required before subsequent engine start.
gearbox
The NIU serves the following functions:
- Provides MIL-STD-1553 and RS422 communications.
- Provides indications of oil temperature, pressure and quantity, oil cooler flap position and fuel flow.
- Controls oil cooler flap and engine/nacelle anti-ice valves.
- Provides engine health and usage monitoring through the EMS. Related functions include diagnostics and fault monitoring, performance monitoring, trend data acquisition, life usage assessment, and propeller balancing data. In addition to the displayed engine parameters; compressor discharge pressure and temperature, vibration sensors, and the CADC system support the EMS.
Blade Angle Scheduling
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. Above 110 knots, the outboard propellers are set to 1° blade angle. Between 110 and 90 knots, the outboard propellers increase from 1° to 8°s blade angle and between 70 and 50 knots decrease back to 1°. The inboard propellers are set at -2° blade angle at all calibrated airspeeds down to 70 knots. From 70 to 50 knots, they are set to 1° blade angle. Below 50 knots all propeller blade angles are set at 1°. This programming supports engine out stops.
When does manual feathering function?
if the START switch is in STOP or if the power levers are at GND IDLE and low-speed ground idle is selected. The auxiliary feather pump is turned on when the PROPELLER CONTROL switch is positioned to FEATHER. The auxiliary feather pump automatically shuts off after 20 seconds.
Reversionary NG Control — The FADEC reversion control mode allows continued safe flight with both engine ___ failed. The reversion mode bases fuel scheduling on __ instead of the normal torque setting. The FADEC fault control logic automatically engages the reversion mode, but closer monitoring of power lever angle and NG is required to ensure symmetric power settings. Maximum available propeller horsepower is reduced by approximately __ percent to ensure that engine power limits are never exceeded. Reverse power is not available.
torque sensors
NG
40
Takeoff Power and Maximum Continuous power ratings are the same when sea level ambient temperature is less than __°F
83
Propeller speed (NP) governing is accomplished by varying propeller blade angle and/or engine fuel flow. The propeller blade angle is controlled by the __ in response to the FADEC signals. The FADEC controls engine fuel flow by providing signals to the __.
PCU
FPMU
The FADEC also protects against gas generator overspeed in normal ___ and ___ of NG.
fuel scheduling and monitoring
FADEC Autofeather Request—The FADEC will request MC permission to autofeather if the power lever is at FLT IDLE or above and any of the following exists:
a. Loss of propeller control (high power and NP below __ percent).
b. At low power settings, low NG (less than __ percent).
c. At high power settings, low engine HP (less than __ percent of commanded HP) and decelerating NG (greater than __ rpm per second).
73
69
74
500
Where is the NIU?
near the FADEC units in the nacelle above the engine
Describe turbine
Two-stage air-cooled, variable speed gas generator turbine; two-stage free power turbine.
If NG exceeds __ percent or NP exceeds __ percent the FADEC automatically shuts down the engine.
109
119
The engine consists of three major assemblies:
a power section (two-rotor system with a free power turbine)
a propeller gearbox (plus propeller),
joined by a torquemeter (shaft and interconnecting struts).
Mission Computer Autofeather Permission — The outboard propellers always have MC permission to autofeather without delay. This supports low minimum control speeds. For the inboard propellers, autofeather permission is granted after a __ second delay provided the aircraft is below __ feet and the other engines are running normally. If these conditions are not met the FADEC will windmill the propeller at 100 percent rpm. This ensures the inboard propeller autofeathers if an engine fails on takeoff. If all engines flameout at least one inboard propeller will be at 100 percent RPM supplying electric and hydraulic power.
2
15,500
Describe compressor
Fourteen-stage axial flow, variable speed compressor. The inlet guide vane and first five stator stages are variable.
What do the FADECs do?
interface with other engine systems, aircraft controls, the distributed air data system, and propeller to provide monitoring and control of the propeller and engine.
The maximum continuous power rating is approximately __ hp at temperatures up to __°F, at sea level with both air conditioners on.
4,700
83
Propeller Underspeed Protection — The FADEC incorporates a software underspeed governor to protect against propeller underspeed. This governor commands the propeller control unit to override the propeller speed and synchrophasing control logic to decrease blade angle and clear the underspeed. Propeller underspeed protection is disabled when the propeller is in the ___.
beta range
Under normal conditions the FADEC protects against propeller and power turbine overspeed in the propeller speed ___.
control logic
What does the ignition system consist of?
two ignitors, two ignition leads, two ignition exciters, and one PMA.
If the auxiliary feather pump is cycled repeatedly without the propeller turning at ___ or above, oil pools in the gearbox. This is because the auxiliary feather pump does not have an ___, and the gearbox oil is only scavenged when the propeller is ___.
LSGI
oil scavenge element
turning
Purpose of the PGB
transmit shaft power from the torquemeter to the propeller, reduce shaft RPM, and provide shaft power to the GMAD.
Mission Computer Automatic Engine Shutdown—The MC continually compares all engines to identify an uncommanded engine thrust increase. If all power levers have been approximately equal for __ seconds, the mission computer looks for one engine HP more than approximately __ HP above the other three engines. If this condition occurs on an engine, and its blade angle is above __ degree, NG is not significantly decelerating, and NP is greater than __ percent, the mission computer commands the FADEC to shut down that engine and feather its propeller. The automatic shutdown system is disarmed/disabled when the __ switch is selected OFF.
5 1100 1 60 ATCS
Automatic Start Control — The FADEC automatically controls the starter, ignition, fuel and propeller systems during start. During ground starts, the FADEC automatically shuts down the engine start sequence for no light-off, flameout, or RPM stagnation. For air starts the start sequence is initiated just as it is on the ground except that the FADEC will not shut down the engine for a ___ start. The FADEC sequences the starter regulating and shutoff valve, ignition, fuel flow, and compressor variable geometry vanes to start the engine.
stagnated
What does the GMAD do?
provides the drive pads for the:
aircraft hydraulic pump an oil cooled ac generator the PGB oil supply and scavenge pump, propeller high pressure oil pump overspeed governor the propeller pitch control unit.
The takeoff power performance rating is approximately __ hp at temperatures up to __°F, at sea level with no bleed air.
4,700
103
The oil system in the core engine and the gearbox scavenge oil back to the oil tank when NP and NG are in the normal operating ranges. With the engine shut down in flight the engine and propeller can windmill at __ speeds, depending on the conditions or failures. These intermediate rpm conditions result in __ in sections of the engine if the FIRE handle is not pulled.
different
oil pooling
