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Terms in this set (69)
The engine __ are the metal panels that cover the engine compartment. These panels __ the engine components, decrease __, and provide an engine air __.
cowlings, protect, drag, intake
The engine cowling supplies the engine with essential __. Air enters the cowling through an opening in the front just below the __ piece.
This air is passed through the __ prior to reaching the engine. The inertial separator causes the air molecules to turn 90° to the engine compartment. __ particles, such as __ or __, are not able to make the turn and are returned to the atmosphere through a __ duct.
inertial separator, heavier, water, debris, bypass
The T-6A is equipped with a Pratt & Whitney __ free turbine, reverse flow design, turboprop engine.
Free turbine refers to the fact that the compressor and power turbines are not __. Air movement from one __ to the other provides power to the propeller
physically connected, turbine
__ design refers to the flow of air through the engine. Air enters the engine at the rear and moves forward during the combustion cycle
There are three elements necessary for engine operation. These elements are:
Air Fuel Heat
The two major sections that make up the engine are the:
There is also an important area aft of the gas generator section commonly referred to as the __ compartment
Gas generation, Power turbine, accessory
The __ compartment is located at the rear of the engine between the left and right cowling doors and contains several aircraft systems. Some of those systems are the:
accessory, gear box, oil, starter/generator, battery
Most of the components in the accessory compartment __ primary components of engine operation. The exception is the __. This turns the compressor __ and compressor which provides air to the engine until it starts and is able to sustain itself.
are not, starter, turbine
The gas generation section is located between the __ compartment and the __ section, and contains the following components:
accessory, power turbine, inlet, compressor, combustion, turbine
Gas Generation Functions 1
__ air enters the engine through the __ inlet and is compressed by a __ axial flow compressor and a single stage __ flow compressor.
inlet, compressor, four-stage, centrifugal
Gas Generation Functions 2
The __ air is transferred to the __ chamber. Here, the compressed air is mixed with fuel and __. Doing this to the mixture causes the gases to expand. The expanding gases drive the __, which perpetuates the cycle.
compressed, combustion, ignited, compressor turbine
The power turbine section is the front section and contains the following components:
turbine, exhaust, reduction gearbox, propellor
Power Turbine Section Functions 1
The power turbine section uses the expanding gases generated by the gas generation section to produce __. After the expanding gases pass through the __ turbine, they drive the __ turbines. Notice how the power turbine rotates in the __ direction of the compressor turbine. This is possible because remember, there is no physical connection between the two turbine sections.
horsepower, compressor, power, opposite
Power Turbine Section Functions 2
The gases flow through the __ system and back into the atmosphere. The __ turbine drives the __, which in turn drives the __ shaft at a reduced RPM.
exhaust, power, reduction gear box, propellor
The engine exhaust system consists of the following components:
Exhaust Purpose and Location
Once the expanding gases have passed over the power turbine, they are ready to be released back into the atmosphere. This is where the exhaust system comes into play.
As the gases come off the power turbine, they are directed to the exhaust __ on either side of the engine. From here, the gases make a __° turn through the exhaust __ before being released rearward. As the gases are released into the atmosphere, they provide a small amount of additional __.
ports, 180, stacks, thrust
Start and Ignition System Purpose
As mentioned earlier, three elements that must be present for proper engine operation are compressed air, fuel, and heat. The starter provides the __, the __ provides the fuel, and the __ system produces the initial heat source.
The T-6A uses a __ ignition system to initiate combustion. This type of ignition system provides quick light ups over a wide range of __.
initial airflow, fuel management unit, ignition, dual spark, temps
The ignition system consists of an ignition __, two high voltage igniter __, and two __ igniters.
The ignition exciter is mounted on the __. An igniter __ runs from the exciter to each spark igniter. The spark igniters are located at the _ and _ o'clock positions around the __ chamber.
exciter, cables, spark, airframe, cable, 4, 9, combustion
Ignition System Operation
To create a spark, the ignition exciter receives a __ input signal. The __ transforms this signal to a __ output signal. Ignition __ carry this high voltage signal to each spark __. The spark igniters provide a spark to the air and fuel mixture in the combustion chamber.
low voltage, exciter, high voltage, cables, igniter
An ignition control toggle switch is located on the __ switch panel in each cockpit (Figure 3-10). Available switch positions are as follows:
right forward, on, norm
During autostart or normal operation, the ignition switch should be placed in the __ position.
With the ignition switch in this position, the igniters initiate when the starter switch is moved to __. The __ energizes and de-energizes the igniters as required during the start sequence. A green __ annunciator illuminates when the igniters are activated.
The __ position is available for continuous igniter operation.
norm, auto/reset, PMU, IGN SEL, on
Power for the ignition system is provided through a circuit breaker labeled __, located on the __ circuit breaker panel in the front cockpit.
IGN, battery bus
The Power Control Lever (PCL) controls __ to the engine, producing __ on the propeller, and ultimately controls the amount of engine power and aircraft speed.
PCLs are located on the left console panel in both cockpits.
fuel flow, torque
The front and rear PCLs are interconnected with a __ rod. As one PCL moves, the other follows. This provides identical control of the propulsion system from either cockpit.
The front PCL is connected to the Fuel Management Unit (FMU) mechanically by a __. It is also connected __ to the FMU. PCL movement physically moves the input lever on the side of the FMU. This fuel request displaces a __ in the FMU which releases the requested amount of fuel.
flexible cable, electrically, cam
An unmarked position located between __ and __ is used during engine start.
To find the start position, move the PCL forward until a green __ light on the __ panel illuminates.
off, idle, ST READY, annunciator
A PCL __ is provided to prevent inadvertent engine shutdown. When the PCL is moved forward to the IDLE position during engine start, two __ lock in place on the front side of the rocker cam detent to secure the gate.
To shut down the engine, raising the PCL __ or pushing the __ down and then raising the PCL cutoff finger lift, moves the rocker cam out of the way and allows the PCL to move to the cutoff position.
cutoff gate, roller bearings, cutoff finger lift, finger lift guard
The PMU is a computer unit located underneath the engine in the __ compartment (Figure 3-14).
The PMU processes __ requests from the PCL and keeps the engine and propeller within __.
In addition, the PMU determines __ power and provides a near linear power response between the PCL __ and __ positions.
accessory, power, operating limits, available, idle, max
The PMU continually interacts with other engine systems to automatically maintain __, __, and __ limitations (N1 and NP).
ITT, torque, RPM
PCL is mechanically connected to the FMU by a __ and electrically connected to the __ by way of the __.
Moving the PCL forward provides a physical input to the __ via the flexible cable, releasing a nominal amount of fuel from the FMU.
An __ signal is transmitted to the __ which fine tunes the power request and sends a signal to the __.
The combination of these inputs produces a near __ power response.
flexible cable, FMU, PMU, FMU, electronic, PMU, FMU, linear
Control of the PMU is provided through a toggle switch labeled PMU and located on the __ switch panel in the front cockpit only. This switch has two available positions, __ and __.
When in the __ position, all PMU functions are active.
right forward, norm, off, norm
With the PMU switch in the OFF position, or if the PMU fails, all __ must be monitored manually.
In addition, __ is maintained solely through the mechanical connection between the PCL and FMU. A __ in engine power is likely if the PMU fails or is turned off in flight.
systems limitations, fuel delivery, step change
Two annunciators are provided to indicate PMU functionality.
An amber __ annunciator illuminates after landing so that maintenance may be alerted that the PMU has accommodated a fault. A PMU STATUS light __ indicates a fault in either of, or a mismatch between the __ switches, alerting the pilot that the PMU will not revert to the __ upon landing.
In addition, the yellow __ light illuminates, and an aural tone is heard.
PMU STATUS, in flight, weight on wheels, ground mode, MASTER CAUTION
The second PMU annunciator is a red __ annunciator. This annunciator illuminates anytime the PMU is __.
Whenever the this annunciator illuminates, it is accompanied by the illumination of the __ annunciator.
In addition, the __ and __ lights flash and an aural tone is heard.
PMU FAIL, nonfunctional, PMU STATUS, MASTER WARN, MASTER CAUT
The primary power source for the PMU comes from the __, which is mounted on the __.
The PMA provides __, which the PMU converts to __. If the PMA fails, power is provided through the __ battery bus.
Permanent Magnet Alternator, reduction gearbox, 32 VAC, DC, 28 VDC
The PMU backup power circuit breaker is labeled __, and is located on the __ circuit breaker panel in the front cockpit.
PMU, battery bus
The starter/generator is attached to the __. A __ connects the compressor section and accessory gearbox.
During engine start, the starter/generator functions as a starter to turn the __ section. Once the start is completed, the starter/generator functions as a __, with the __ turbine powering the starter/generator and the other accessories attached to the gearbox.
accessory gearbox, shaft, compressor, generator, compressor
During engine start, the starter motor turns the __ via linkage in the accessory gear box. This generates __ and __ until the engine starts and is able to run at idle speed.
Once the engine is self-sustained, the starter becomes a __. The generator is driven by the engine via linkage in the __. The generator provides __ power, which powers many of the aircraft systems and charges the battery and the auxiliary battery to __ VDC.
compressor, airflow, compression, generator, accessory gearbox, 28 VDC, 24
The starter is initiated by a switch on the __ switch panel in each cockpit. Each switch has the following three positions:
right forward, auto/reset, norm, manual
The __ position is used for most engine starts. To start the engine, momentarily place the starter switch in this position. The switch is spring loaded and automatically returns to the __ position.
The MANUAL switch position is available, but is not used under normal circumstances. If a start attempt is automatically or manually __, the MANUAL switch position is selected to manually motor the engine by holding the starter switch in this position for __ seconds with the PCL __.
AUTO/RESET, norm, aborted, 20, off
When ready to start the engine, move the PCL forward until the green __ annunciator illuminates.
The ignition switch should be in the __ position.
The final step in the start procedure is to move the starter switch to the __ position momentarily.
A green __ annunciator illuminates when the igniters are energized. The engine continues the start cycle on its own.
The annunciators __ during the start sequence. You will learn the complete start sequence in detail in a later lesson.
norm, AUTO/RESET, IGN SEL, extinguish
Power for the starter is provided through a circuit breaker labeled __ located on the __ circuit breaker panel in the front cockpit.
START, battery bus
The oil system provides a steady flow of filtered oil to the engine __, reduction __, __ drives, and __. Without proper lubrication, these systems would overheat, seize up, and fail to operate.
The oil system includes a __ system, __ system, and __ system. The oil system is designed such that oil pressure values are maintained during normal and aerobatic flight.
bearings, gears, accessory, propellor pressure, scavenge, cooling
Oil must be pressurized to ensure lubrication of the necessary parts; this is done by the __ pump. This must also supply pressure during inverted or negative G flight. There are two oil pickups inside the oil tank. The first pickup is in the __ of the tank and is submerged in oil during __ flight operations.
A second pickup, located near the __ of the tank, ensures a constant flow of oil during __ flight.
pressure, center, normal, top, inverted
After the pressure pump supplies oil to the bearings, reduction gears, accessory drives, and propeller, a __ system returns the oil to the oil tank.
The system uses several __ and __ pumps like the one shown here to replace the oil in the oil tank. Pumps are placed in various locations throughout the oil system.
scavenge, pressure, scavenge
The scavenged oil is then routed through the oil __ before the oil is returned to the oil __.
Oil is filtered by a main oil filter in the __. There are also several oil strainers located in the __, __, and __ drive areas. If the main oil filter gets clogged, a filter __ valve allows unfiltered oil to continue lubricating the engine.
oil tank, power, compressor, accessory, bypass
The oil system also incorporates a __ detector system. This detector sensor is located in the __ gearbox. This sensor detects metallic particles in the oil and warns the pilot of possible __ damage.
If metal particles are detected in the oil, a red __ annunciator illuminates, the __ light illuminates, and an aural tone is heard.
chip, reduction, gear. chip, MASTER WARN
Oil levels can be checked by removing the dipstick from the fill port and visually inspecting the oil levels on the dipstick. This method is only valid within __ minutes of engine shutdown.
A second means for checking oil levels is provided through a __ on the side of the oil tank. This method is not used because it is not as accurate as the dipstick method.
30, sight glass
Oil temperature and pressure are measured by the same ports on the engine, but a signal is sent to both the __ display in each cockpit and a __ computer. The second one contains logic to illuminate the __ under certain oil pressure conditions discussed in this topic.
engine/systems, signal conditioning unit, CWS
During steady state conditions, normal oil pressure should be between __ and __ psi (green area on display). Refer to abnormal operations if oil falls outside this range.
The exception to this is during aerobatics or spins. During aerobatics or spins, oil pressure should be between __ and __ psi. Oil pressure below normal should be corrected before next flight.
90, 120, 40, 130
An amber __ annunciator illuminates when oil pressure is between __ and __ psi at __ power or between __ and __ psi for __ seconds above __ power.
If oil pressure is __ psi or below at IDLE power, or __ psi or below above IDLE, the red OIL PX annunciator illuminates.
If oil pressure remains between 15 and 40 psi at IDLE power for _ seconds or more, both the __ and __ OIL PX annunciators illuminate.
A __ and/or __ light illuminate with each annunciator and an aural warning tone is heard.
OIL PX, 15, 40, IDLE, 40, 90, 10, idle, 15, 40, red, 5, red, amber, MASTER WARN, CAUTION
Power for the oil pressure transducer is provided through a circuit breaker labeled __, located on the __ circuit breaker panel in the front cockpit.
OIL TRX, battery bus
The purpose of the propeller is to convert power into thrust. The T-6A uses a four blade, variable pitch, __propeller. The PMU and the Propeller Interface Unit (PIU) control __ (NP) to maintain a constant propeller speed of __ RPM (100% NP) and achieve varying levels of thrust by automatically adjusting propeller __.
100% torque is available from sea level to approximately __ to __ feet MSL on a standard day. Above 16,000 feet MSL, a decrease in the maximum torque available is noted.
constant speed, propeller speed, 2000, pitch, 12,00 16,000
The propeller is driven by the __ turbine, through the reduction gearbox. The reduction gearbox transfers power generated by the engine to the __, reducing engine output from __ RPM to the propeller operating speed of 2,000 RPM
power, propellor, 30,000
Propeller speed (NP) is measured by a __ located in the reduction gearbox. Data from the torque probe is continually monitored by the __.
phase shift torque probe, PMU
The PMU directs the __ to maintain propeller RPM at 100% (2,000 RPM) using an __ governor. A backup __ overspeed governor does not allow propeller RPM to exceed __% (2,120 RPM.)
If the PMU or PIU fails, propeller RPM is __ regulated by the backup system. If this system is used, the mechanical flyweight overspeed governor resets to maintain RPM at 100 ±2% (2,000 RPM.)
PIU, electronic, mechanical, 106, automatically
Propeller pitch changes are based upon the changes in __. The PIU responds to power requests from the PMU by regulating oil pressure to the __ mechanism. The PIU __ the pressure of the oil that is transferred from the __ through a tube and stationary transfer sleeve into the hollow __ shaft. Changes in oil pressure result in changes to propeller pitch.
oil pressure, pitch change, increases, PIU, propellor
There are three basic blade angle or propeller pitch conditions. These conditions are based upon the measure of the angle between the __ of the propeller and the __ of the blade.
These conditions are:
__ (flat or fine)
plane of rotation, chord line, feathered, high pitch, low pitch
In the __ condition, the blade is aligned nearly straight into the wind, approximately 86° from the perpendicular plane. This position produces the least amount of __ and no __. Without __, the counterweights and feathering spring force the propeller blades to this position.
feathered, drag, thrust, oil pressure
__ is variable between feather and low pitch. The propeller will be in this position during most flight conditions.
In the __ condition, the propeller blades are approximately 15° from the perpendicular plane. The propeller blades produce some __ and the most __. The propeller will be in this position during low __ and low __ flight.
low pitch, thrust, drag, speed, throttle
The propeller is naturally pulled to the __ position by the feathering spring and the counterweights.
The __ mechanism uses the oil system to force the propeller blades away from feather. Oil for this system is provided by the engine oil system and regulated by the__.
As the PIU increases oil pressure, the sliding piston is forced __, rotating the propeller blades toward __ pitch.
Because the counterweights are connected to the __, they are also repositioned by the increased oil pressure.
feathered, pitch change, PIU, forward, low, blade root
If there is an engine failure during flight, oil pressure to the pitch change mechanism is lost and the propeller moves toward __.
However, if any residual oil pressure remains from windmilling, the __ attempts to maintain propeller pitch and the propeller may not feather. To feather the propeller, place the PCL in the __ position. This position activates two separate control valves within the PIU. The first is a microswitch which activates the __ solenoid valve. The second, controlled by the PMU, releases __. Oil pressure being released by either valve allows the feathering spring and counterweights to feather the propeller.
feather, PIU, off, feather dump, oil pressure
The feather dump solenoid valve receives power through a circuit breaker labeled __, located on the __ circuit breaker panel in the front cockpit.
PROP SYS, battery bus
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