T-6A Propulsion 1 SY103 Flashcards
Describe the engine cowling and it’s functions
The metal panels that cover the engine, decreasing drag and providing air intake.
What is the P&W PT6A Free Turbine
This refers to the fact that the compressor and turbines are not physically connected.
Air movement from one turbine to the other provides power to the propeller.
What is Reverse Flow
When air enters the engine at the rear and moves foreword during the combustion process.
What 3 elements are necessary for engine operation
Air
Fuel
Heat
What are the 3 major sections of the engine
Accessory compartment, gas generation section, power turbine section
Gas Generation Section Location and components
-Located between accessory compartment & power turbine section- Compressor inlet Compressor Combustion chamber Compressor turbine
Gas Generation Functions 1
Air enters engine via compressor inlet, compressed by four-stage axial flow compressor and single-stage centrifugal flow compressor
Gas generation functions 2
Compressed air transferred to combustion chamber, compressed air mixed with furs and ignited, ignited mixture expands, expanded gassed drive compressor turbine, this perpetuates the cycle
Power turbine location and components
-locates on the front section- Power turbines Exhaust case Reduction gearbox Propeller shaft
Exhaust components
Exhaust ports
Exhaust stacks
Exhaust purpose and location
-located on either side of the engine-
Gassed released rearward into the atmosphere providing small amount of additional thrust
Ignition system type and purpose
Type: dual ignition
Starter provides airflow, FMU provides fuel, ignition system produces heat source
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PENIS
Ignition location and components
-ignition exciter mounted on the airframe-
Ignition exciter
2 high voltage igniter cables
2 spark igniters
An ignited cable runs from exciter to each igniter. Igniters locates at 4 and 9 o’clock positions around combustion chamber
Ignition control switch 1 location and positions
-located on right foreword switch panel in each cockpit-
Positions:
On
Norm
Power Control Lever (PCL) location and purpose
-located on left console panel in both cockpits-
Controls fuel flow to the engine, producing torque to the engine, thus controlling engine power and aircraft speed
How are PCLs connected
Front and rear PCLs are interconnected with a push-pull rod, providing identical control
PCL positions 1
Max
Idle
Off (aft most position, used for shutdown)
PMU location and purpose
-Located underneath the engine in the accessory compartment-
Processes power requests from PCL, primary function is to keep propeller within operating limits.
PMU Switch 1 positions and location
-located on the right foreword switch panel-
Norm
Off
When I’m Norm, all PMU functions are active
PMU switch 2
With PMU in off position (or if PMU Fails) all system limitation must be monitored manually
PMU Status Indicators
Amber PMU STATUS: illuminates after landing so maintenance can be alerted the PMU has accommodated a fault.
PMU Status light in flight: Indicates in either of, or mismatched between the weight-on-wheels switches (the PMU will not revert to the ground mode upon landing)
PMU Fail Indicators
PMU FAIL Is the second annunciator and is red. Indicates that the PMU is Non-functional
Accompanied by the illumination of the PMU STATUS indicator
MASTER WARN and MASTER CAUT lights flash and aural tone is heard
PMU Power
The primary source of power comes from PMA (Primary Magnet Alternator, mounted on reduction gearbox)
PMA provides 32 VAC, which the PMU converts to DC. If PMA fails, power is provided through 28 VDC battery bus
PMU Circuit Breaker
the circuit breaker is labeled PMU and located on the battery bus circuit breaker panel in the front cockpit
Starter Location and Components
-The starter/generator is attached to the accessory gearbox. A shaft connects the compressor section and accessory gearbox-
During engine start, the starter/generator functions as a starter. after engine start, it acts as the generator.
Starter Purpose
During Start: turn compressor in the accessory gearbox.
After Start: It becomes the Generator, provides 28 VDC power, which powers many aircraft systems, and charges the battery to 24VDC
Starter Switch Location and Positions
Located on the right foreword switch panel in each cockpit.
Auto/Reset
Norm
Manual
Starter Positions
“Auto/Reset”: Used for most engine starts
“Manual”: Used to manually motor the engine by holding for 20 sec (not normally used)
Engine start sequence
- PCL foreword until green ST READY Shows
- Ingnition switch in NORM
- Move starter to AUTO/RESET Position momentarily
- green IGN SEL when igniters are energized
- Annunciators extinguish during start sequence
Oil System Purpose
The system provides steady flow of oil to engine bearings, reduction gears, accessory drives, and propeller.
System includes: pressure system, scavenge system, cooling system
Oil System Components
Oil Pump Oil Scavenge System Oil Cooler Chip Detector Oil Filter
Oil Scavenge System
Returns the oil to the oil tank
Oil Cooler
Scavenged oil is routed through the oil cooler before being returned to oil tank
Oil Filter
Is also the bypass
Filters the oil in the oil tank
Chip Detector
Located in the reduction gearbox, and senses metal particles and warns the pilot of possible gear damage
If metal is detected: red CHIP light illuminates and MASTER WARN light illuminates. (Tone also Heard)
Oil Pressure Signals
Temp and pressure Measured by same ports in engine, but sent to both the engine/Systems display and a signal conditioning unit (SCU)
Oil pressure range
Should be between 90-120 (green area on display)
during acrobatics should be between 40-130
Propeller Purpose
The purpose of the propeller is to convert power into thrust. (4-blade, variable pitch, constant speed)
PMU and PIU control propeller speed (Np) to maintain Prop speed of 2000RPM
When is 100% torque Available
From sea level to ~12,000 to 16,000’ MSL
Reduction Gearbox
Transfers power generated by the engine to the prop, reducing engine output from 30,000RPM to prop operating speed of 2,000 RPM
FMU connections
PCL is connected to the FMU via a flexible cable, and electrically connected the the FMU by way of the PMU
